2006_Mar_SMT

TraceabilitySystem

Error-proof Your

The Industry’s Only Dedicated Surface Mount Technology ResourceThe Industry’s Only Dedicated Surface Mount Technology Resource

Jetting: Dispense Technology of Choice

Lead-free: Matte Finish Solder Joints

SMT 101: Solder Materials

March 2006

www.smtmag.com

I N S I D E :

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Everyone has questions regarding pending deadlines

for compliance with the European Union’s new RoHS

lead-free directive. Fortunately, AMTECH has all the

answers, including a complete line of environmentally

friendly lead-free solder products. AMTECH offers:

• Solder paste

• Solder powder

• Core wire

AMTECH lead-free solder pastes are made from

world class AMT Unisphere™ powder for enhanced

solderability, which contains <200 ppm of lead,

guaranteed. AMTECH is also your exclusive source

for SynTECH-LF, a unique lead-free,

no-clean solder paste formula made

with proprietary synthetic poly-adduct

components. SynTECH-LF has been

proven to increase process line

yields with less beading, scrap

and rework.

For sensible answers to all your

lead-free questions, call the

experts at AMTECH.

It’s that easy.

AMTECHwww.amtechsolder.com

75 School Ground Rd., Branford, CT 06405 USA

(800) 435-0317 • (203) 481-0362 • Fax (203) 481-5033

We’vemadelead-freeeasy.

F I L L I N G T H E V O I D

For RoHS-compliant solder products,

AMTECH has all the answers.

• Solder spheres

• Solder preforms

• NVOC liquid flux

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Fast & Easy RoHS Compliance Screening

• Real-time nondestructive chemical analysis

• Quantifi es total Pb, Cd, Hg, Cr and Br in seconds

• Test solders, components, packaging and more

• Little to no sample prep required

• Handheld or benchtop operation via wireless PC interface

NITON AnalyzersBillerica, MA USA800-875-1578+1 [email protected]

Sales & Service Worldwidewww.thermo.com/niton

Analyze • Detect • Measure • Control™



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EMS Trends

®

SMT

Surface Mount

Technology®

Magazine

c o n t e n t sf e a t u r e s

COVERSTORY

www.smtmag.com March 2006/SMT 3

This month on the web

departments5 How to Contact SMT

10 News

11 Calendar

37 SMT Industry Directory

37 Advertiser Index

38 SMT Marketplace

columns6 Speaking of SMT

Gail Flower

7 Surface Mount Manufacturing Robert Rowland

8 Surface Mount Global Process Design Evelyn A. Baldwin

9 Surface Mount Components Craig Hunter

40 SMT Perspectives Joe Belmonte

Check out IPC’s Book-to-Bill Ratio for December 2005.Keep up with the latest industry happenings and newest products on SMT online.Be sure to subscribe to our HTML format e-newsletter, delivered every other Wednesday.Find out about the newest and hottest industry events in the Conferences and Events section.

12 Traceability Data Integrity — Challenges and Solutions The electronics manufacturing industry is seeing increased demands for material traceability. Traceability requirements once limited to high-reliability applications are becoming a necessity in other sectors. OEMs feel it is pointless to request traceability without checks and balances in place to ensure accuracy. This is motivating assemblers to error-proof traceability systems. By Mitch DeCaire

18 Jetting: Dispense Technology of Choice for AdhesivesMany manufacturers choose jetting technology to meet the demands of automated adhesive application processes. As more manufacturers in a variety of industries become aware of its advantages, jetting will become increasingly popular as the dispense technology of choice for adhesives. By Al Lewis

20 Analyzing the Debate of Clean vs. No-clean Most consumer-based products have adapted a true no-clean strategy, primarily due to rapid technological changes within the market. This study illustrates that products manufactured using a no-clean label are not a guarantee of long-term reliability. By Umut Tosun, M.S.,Ch.E, and Harald Wack, Ph.D.

24 Identifying Stencils for Lead-free Solder Paste July 1, 2006 marks the era of lead-free electronics in Europe. The infl uence of RoHS and WEEE will result in better environmental quality, protection of human health, and more rational use of natural resources. But the removal of lead from electronics will bring massive changes for all companies in the supply chain. By Holly Wise

27 Matte-fi nish Solder Joints After Lead-free Wave SolderingMost joints soldered using lead-free alloys exhibit a dull or frosty appearance, which differs from the smooth, bright, shiny surfaces of tin/lead solders. This article looks at several reasons for this phenomenon. By Gerjan Diepstraten

30 Due Diligence Verifi cation — Ensuring RoHS Compliance RoHS compliance will require manufacturers to incorporate measures to ensure all electronic components meet the EU’s directive. This article looks at the program one EMS provider instituted to document this compliance. By Scott Mazur and David Mercuro

Step-by-Step

32 Step 3: Solder MaterialsGreater than 60% of end-of-line defects in SMT assembly can be traced to solder paste and the printing process. Another 15% occur during refl ow. Using designed experiments and the measurement of critical solder paste-related process metrics, a solder paste evaluation procedure was developed to maximize information about the paste and its processability, while minimizing experimentation. By Timothy Jensen and Ronald C. Lasky, Ph.D., PE

ON THE COVERThe article on page 12 emphasizes the need for material traceability within many sectors of electronics manufacturing.

To see your company’s most recent news on the Website, e-mail Lee Mather, assistant editor, at [email protected], or call her at (603) 891-9176. Cover image courtesy of Cogiscan.

M A R C H 2 0 0 6

V O L U M E 2 0

N U M B E R 3



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alpha

®EF-6100

Introducing ALPHA® EF-6100. The high-reliability, low-solids,alcohol-based, no clean wave soldering flux that meets thechallenges of lead-free and tin-lead processing.

When you convert to lead free, you want the excellent board cosmeticsand minimal flux residues associated with low-solids fluxes. But you cannotsacrifice high electrical reliability for solderability. With ALPHA® EF-6100,the next generation wave soldering flux you get it all:

• Superior residue cosmetics

• Best-in-class electrical reliability, passing IPC, Bellcore, and JIS surfaceinsulation resistance (SIR) and Bellcore and JIS Electromigration (EM)

• Excellent soldering performance in lead-free and tin-lead processes.

ALPHA® EF-6100 will help you transition to lead-free seamlessly and cost-effectively. Let’s face it, the world is changing. At Cookson Electronics, webelieve change shouldn’t come at the expense of performance.

GO TO www.newalphaproducts.com for more informationOr, contact your Cookson Electronics representative.

Worldwide Headquarters • 600 Route 440 • Jersey City, NJ 07304 • USA • +1-800-367-5460 • www.alphametals.comEuropean Headquarters • Forsyth Road • Sheerwater • Woking GU215RZ • United Kingdom • +44-1483-758-400Asia-Pacific Headquarters • 1/F, Block A • 21 Tung Yuen Street • Yau Tong Bay • Kowloon, Hong Kong • +852-3190-3100

Are you sacrificingelectrical reliabilityfor low flux residue andgood board cosmetics?



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www.smtmag.com

E D I T O R I A LO F F I C E S

S A L E S O F F I C E S W O R L D W I D E

SMT® (Surface Mount Technology) is published by PennWell Corporation © 2006 PennWell Corporation. Authorization to photocopy items for internal or personal use, or the internal or personal use of specifi c clients, or for educational use, is granted by the copyright owner, provided that the appropriate fee is paid directly to Copyright Clearance Center, 222 Rosewood Drive, Danvers, MA 01923 USA (978)750-8400. PennWell Corporation does not assume and hereby disclaims any liability to any person for loss or damage caused by errors or omissions in the material contained within this publication, regardless of whether such errors or omissions are caused accidentally, from negligence or any other cause.

March 2006, Volume 20, Number 3 • SMT© (Surface Mount Technology©) (ISSN 1529 8930) is published 12 times a year, monthly, by PennWell Corporation, 1421 South Sheridan Road, Tulsa, OK 74112, telephone (918) 835-3161; fax (918) 831-9497; web address http://www.pennwell.com. © 2006 PennWell Corporation All Rights Reserved. Subscriptions: (847) 559-7500 7:30a.m.-6p.m. CST. Free to qualifi ed professionals, all others in the U.S., Canada, and Mexico, $109.00; all other countries, $198.00; one-year (12 issues). POSTMASTER: send address changes to: Surface Mount Technology, P.O. Box 3423, Northbrook, IL 60065. Return Undeliverable Canadian Addresses to: P.O. Box 1632, Windsor, ON N9A 7C9. Periodicals Postage Paid at Tulsa, OK, and at additional mailing offi ces. Printed in the United States of America. GST NO. 126813153. Publication Mail Agreement No. 40052420.

Cookson Electronics

Lead-Free Wave

Soldering

Technologies

alpha

Our wave soldering products arepart of the world’s most completeline of lead-free solutions. Theirproven compatibility helps youtransition to lead-free processesseamlessly.

• ALPHA Vaculoy SACX0307 –Wave Solder Alloy, high yield, fastthroughput, economy, reliability

• ALPHA Telecore Plus Cored Wire– complete lead-free compatibility,activated rosin, halide-free fluxcore, non-corrosive residues

• ALPHA EF-Series Flux – lead-freecompatible, excellent hole-fill,minimal bridging, best-in-classsolderball resistance

GO TO www.newalphaproducts.com for more information

Or, contact your CooksonElectronics representative.

Americas + 1-800-367-5460Europe + 44-1483-758-400Asia + 852-3190-3100

www.cooksonelectronics.com

GROUP PUBLISHER: Jay Regan, (603) 891-9126; E-mail: [email protected]

EDITORIALEDITOR-IN-CHIEF: Gail Flower,

(603) 891-9395; E-mail: [email protected] EDITOR: Michelle M. Boisvert,

(603) 891-9310; E-mail: [email protected] EDITOR: Lee Mather,

(603) 891-9176; E-mail: [email protected] EDITOR: Julia Goldstein, Ph.D.,

E-mail: [email protected]

PRODUCTION SERVICESART DIRECTOR: Kelli Mylchreest

SENIOR ILLUSTRATOR: Christopher HippPRODUCTION MANAGER: Barbara Ann Burgess

AD TRAFFIC CLERK: Richard Shepard, (918) 831-9519; E-mail: [email protected] MANAGER: Jayne Sears-Renfer, (603) 891-9416; E-mail: [email protected] COMMUNICATIONS MANAGER:

Carol Fronduto-Dirksen, (603) 891-9169; Fax: (603) 891-9290; E-mail: [email protected]

REPRINTS: Rhonda Charron, (603) 891-9121; Fax: (603) 891-9328; E-mail: [email protected]

SUBSCRIPTION SERVICES: (847) 559-7500; Fax: (847) 291-4816;


EDITORIAL OFFICEPennWell Corporation,

SMT, Advanced Technology Division98 Spit Brook Road, Nashua, NH 03062

(603) 891-9395; Fax: (603) 891-9328

ADVANCED TECHNOLOGY DIVISIONSENIOR VP ELECTRONICS AND

IT GROUP: Mark FinkelsteinVP, AUDIENCE DEVELOPMENT:

Gloria S. AdamsGROUP PRODUCTION DIRECTOR: Mari Rodriguez

GROUP ART DIRECTOR: Meg FuschettiCORPORATE OFFICES: 1421 South Sheridan Rd.,

Tulsa, OK 74112; Tel: (918) 835-3161

CORPORATE OFFICERSCHAIRMAN: Frank T. Lauinger

PRESIDENT AND CEO: Robert F. BiolchiniCHIEF FINANCIAL OFFICER: Mark C. Wilmoth

U.S. ADVERTISING & ONLINE ADVERTISING SALESNational Sales Manager,

Laura Dugdale, (603) 891-9401; Fax: (603) 891-9328;


INTERNATIONAL ADVERTISING SALESLondon, Amanda Loftus, Tel: 44-1793-862111;

Fax: 44-1793-862110; E-mail: [email protected]

Paris, Luis Matutano, Tel: 33 (0) 1-39-66-16-87;

Fax: 33 (0) 1-39-23-84-18; E-mail: [email protected]

Munich, Johann Bylek, Tel: 49-89-904-80-144;

Fax: 49-89-904-80-145; E-mail: [email protected]

India, Rajan Sharma, Tel: 91-11-6861113;


Korea, Seo Yeo-jung, Tel: 82-2-322-0525;

Fax: 82-2-323-5324; E-mail: [email protected]

Japan, Manami Konishi, Tel: 81-3-3556-1575;


Taiwan, Cindy Yang, Tel: 886-2-2396-5128;


Hong Kong & China, Adonis Mak, Tel: 852-2-838-6298;


Singapore, Thailand, Malaysia, Philippines,

Ms. Adeline Lam, Tel: 65-6-836-2272;


Italy, Jean-Pierre Bruel, Tel: 39-03-1751494;


CLASSIFIED, DIRECTORY & MARKETPLACE ADVERTISING SALES

Rhonda Charron, (603) 891-9121;

Fax: (603) 891-9328; E-mail: [email protected]

LIST RENTALS Bob Dromgoole, (603) 891-9128, Fax: (603) 891-9341;


ATD DIRECTOR OF INTERNET SERVICES Tom Cintorino, (603) 579-9002; Fax: (603) 579-9030;




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G A I L F L O W E R

Speaking ofSMT

EditorialAdvisoryBoardBoard Design and AssemblyVern SolbergTessera Technologies Inc.San Jose, California

Business ManagementGary TanelTechBiz ConsultingDallas, Texas

CleaningMichael KonradAqueous Technologies CorporationRancho Cucamonga, California

ComponentsCraig HunterAVX Corp.Myrtle Beach, South Carolina

Design and ManufacturingRay P. PrasadRay P. Prasad Consultancy GroupPortland, Oregon

Electronic Packaging and AssemblyDennis Derfi nyMotorola Inc.Schaumburg, Illinois

Fine-PitchRobert RowlandRadiSys Corp.Hillsboro, Oregon

Global Process DesignEvelyn Baldwin3M EMMDN. Andover, Massachusetts

Materials ScienceJennie S. HwangH-Technologies Inc.Cleveland, Ohio

Process OptimizationRon LaskyIndium Corp. of AmericaMedway, Massachusetts

Surface Mount AssemblyKim HylandSolectron CorporationMilpitas, California

H ave you noticed that many of the associations and trade shows seem to be comprised of the same people who have been

in the industry for quite a while? Everyone seems to have known one another for a period of time. Con-ferences deliver the same message to the same audience. You begin to question if engineers are still excited about careers in our fi eld, if universities are graduating as many engineers as in the past, and if the rewards are as promising as when Jobs and Wozniak created Apple. I remember when attendees at SMTA

meetings would pull me aside to talk about their latest ideas for changing the world. Are we still as motivated as in the past? What message comes from electronics in general to the youth of the next generation?

I recently visited YESTech’s president, Don Miller. He formed this company after leaving a job working for a major AOI/X-ray

fi rm, and decided to form his own company in 2002. He and a partner created the employee-owned com-pany, and supply the industry with the same tools using off-the-shelf components integrated into lower-cost, high-quality products for AOI and X-ray. By not reinventing the wheel, but instead using components from existing suppliers, they were able to build an affordable product and a viable, healthy company.

Our next stop was Los Angeles-based P. Kay Metal, where presi-dent Larry Kay demonstrated their chemistry for dross elimi-nation: MS2 100 PB surfactant

for leaded solder pots and MS2 200 LF for lead-free wave solder pots. The patent-pending chem-istry came about when his fi rm, offering solder paste (wire and bar), fl ux, and dross-reclamation services, developed the material to help remove dross. When you reduce the amount of dross pro-duced in the wave soldering process,

profi ts go up and material is used more effi ciently.

We also visited Westlake Village, Calif.-based Smart Sonic to talk to company president Bill Schreiber. This company has just formed another fi rm, SMT Detergent Corp., to distribute the 440-R SMT Detergent. Though the company developed the original ultrasonic stencil-cleaning process in 1989, it took a while to demonstrate that it could clean all types of solder paste at low-power densities. Proprietary detergent and mechanical effi ciency of the ultrasonic cleansers helped the company grow steadily.

Many inventions occur as a natu-ral progression when people mature in their fi eld. Perhaps the best way to encourage this entrepreneurial spirit among youth is to support involve-ment early. Invite a college student to attend local association chapter meetings. Support student scholar-ships presented by SMTAI and other organizations. Hire interns and sup-port university-based research. The vitality of electronics depends on it. As my father often said, “Learning is a lifelong endeavor that begins early and never really ends.” SMT

“Perhaps the best way to encourage

this entrepreneurial spirit among

youth is to support involvement early.”

Gail FlowerEditor-in-Chief

Fostering the Entrepreneurial Spirit

6 SMT/March 2006 www.smtmag.com



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R O B E R T R O W L A N D

The transition to lead-free soldering is a giant puzzle. Trying to assem-ble it has been a massive under-taking because there are so many pieces. Like many of you, I have

been working on this puzzle for several years. Fortunately, the pieces are start-ing to fi t together, and more is being com-pleted. Our industry still has a lot to do, but there is enough momentum at this point that we should be able to comply with the July 1, 2006, deadline. Following are six frequently asked questions (FAQs) to help solve part of the puzzle.

Does the lead in solder exemptions include components?What is covered under “Lead in solders for servers, storage and storage array sys-tems, network infrastructure equipment for switching, signaling, and transmission, as well as network management for telecommu-nications?” The conservative interpretation is that this includes lead in solder joints and BGA solder balls only, and does not include lead in lead frames (QFP, SOIC, etc.) and end-terminations (capacitors, resistors, etc.).

EU Guidance Document interpretation: This exemption was introduced to allow the use of lead in solders for professional, high-reli-ability applications such as servers and net-

work infrastruc-ture equipment, for which viable lead-free alterna-tives have not been identifi ed. It is the department’s view that this applies to

the whole of the computer and its compo-nents, including processors, memory boards, power converters, power supplies, enclosed housings, modular power subsystems, and adapter cards.

Can you stockpile product made before July 1, 2006?It depends on whether the product is ready to be “put on the market.” This refers to fi nished products, not individual parts or subassemblies. When a product enters the EU, it has not been “put on the market” if it requires additional assembly. This takes place when the product is made available for the fi rst time — when it is transferred from manufacturing to distribution.

What lead-free solder alloy should I use?SAC305 (Sn96.5Ag3.0Cu0.5) is emerg-ing as the general-purpose lead-free alloy. Lead-free solder-alloy evolution started with iNEMI and their recommendation of the SAC (SnAgCu) alloy Sn95.5Ag3.9Cu0.6 for refl ow soldering and Sn99.3Cu0.7 for wave soldering. The IPC Solder Prod-ucts Value Council recommended the Sn96.5Ag3.0Cu0.5 alloy based on “equiva-lent performance and lowest material cost.” SnCuNi alloys also have emerged as another option for lead-free wave soldering.

Can I use my existing wave solder pot?No, for two reasons. Lead contamination is always a possibility, no matter how well a solder pot is cleaned. Lead-free solder will dissolve the natural protective coating on stainless steel, which eventually will cause corrosion of untreated stainless-steel wave soldering hardware. Solutions to this include cast-iron solder pots; ceramic-coated pots; or nitride-coated, stainless-steel pots.

What surface fi nishes are acceptable?The iNEMI Tin Whisker User Group pub-lished “Recommendations on Lead-Free Fin-ishes for Components Used in High-Reliabil-ity Products.” It contains three surface fi nish categories: Desirable fi nishes: NiPd, NiAu, NiPdAu, matte Sn with Ni under plate, matte Sn with Ag under plate, Sn refl owed, Sn hot-dipped, SnAg hot-dipped, and SnAgCu

hot-dipped. Less desirable fi nishes: SnCu hot-dipped; SnAg, 2−4% Ag; matte-Sn, 150°C anneal; matte-SnCu, 150°C anneal; and SnBi, 2−4% Bi. Finishes to avoid: Matte Sn, SnCu, bright Sn, Ag, and AgPd.

Tin whisker mitigation methods include:• Non-Sn plating: noble metal alloys that

do not contain Sn;• Under-layer plating: Ni or Ag layer

between Sn and base metal; • Fusing-Sn plating: reflow process using a

hot-oil bath; • Hot-dipped–Sn: Applied using a molten-

Sn bath; • Annealed-matte–Sn: 150˚C for one hour; • SnBi alloys: Bi content range 2−4% (do

not use with tin/lead solder); • SnAg alloys: Ag content range 2−4%;• Increase Sn thickness: minimum thickness

without under-layer plating of 10 µm; min-imum thickness with under-layer plating of 2 µm.

Other than surface fi nish, how are lead-free PCBs affected?Surface fi nish gets most of the attention, but other issues are:• Glass transition temperature (Tg) is the

temperature at which polymer materials transition from a rigid to soft state.

• Coefficient of Thermal Expansion (CTE) is the amount of material expan-sion that occurs above and below Tg, usu-ally expressed in ppm/˚C.

• Material decomposition temperature (Td) is the temperature at which the material breaks down due to thermal exposure.

• Time to delamination (T260 and T288) is the amount of time at a single tempera-ture (260˚ or 288˚C) that the material can withstand before delaminating. SMT

Robert Rowland is an SMT Editorial Advi-sory Board member, instructor and co-au-thor of Applied Surface Mount Assembly. He currently is the process engineering manager at RadiSys Corp. in Hillsboro, OR, and technical conference director of SMTA International. He also is an active member of the SMTA and a recipient of the SMTA Founder’s Award. Contact him at (503) 615-1354; e-mail: [email protected].

The RoHS and Lead-free Puzzle

“The transition to

lead-free soldering

is a puzzle. Trying to

assemble it has been a

massive undertaking….”

Speaking ofManufacturing



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E V E L Y N A . B A L D W I N

Speaking ofGlobal Process Design

This is the fi rst in a series of articles I will write related to global pro-cess improvements. As our world becomes increasingly more com-plex and interconnected at the same

time, it becomes imperative to develop pro-cesses that work across disciplines, geog-raphies, and our customers’ companies. I think we all would agree that the only rea-son any of us are in business is because our customers exist. Only by continuing to sat-isfy them can we look forward to future success and profi tability.

I think we also would agree that as the global business climate becomes more com-plex and interconnected, it is increasingly diffi cult to satisfy the customer, especially when each has specifi c needs, challenges, and competitive conditions. That is one of the many reasons why I say, “Thank good-ness for process improvement tools such as six sigma and methods that help manage our business in this global environment.” I strongly believe that these tools can help companies build value with customers. If customers are why we are here, making our operations work better is how we serve

those customers.Internally, tools

such as these drive improvements across the broad spectrum of business processes and geographies. This translates into

a signifi cant competitive advantage, of which we’ve seen proof time and again. If you’ve been successful with business pro-cess improvements internally, the next log-ical step is to bring what you have learned and apply it to your customers’ processes. In the rush to launch process-improve-ment efforts with customers however, it is important to remain focused on some important criteria.

Understand Customer Processes and Problems First, customer projects must be designed to address customer pain-points and solve problems generated by a customer pro-cess. This should be done using customer-defi ned metric. For example, a project dis-guised as “for the customer” that is actually intended to accelerate payment to your own company isn’t a customer project. In fact, the outcome of a project that is truly

“for the customer” may actually reduce some of your business with them in a cer-tain area. When customers see improve-ments that you have helped achieve, their loyalty will likely benefi t your company in other ways.

Identify Meaningful ProjectsThere are several areas to explore for improvement efforts. While quality issues come to mind fi rst, others abound. Sup-ply chain, product performance, manufac-turing productivity, safety, and fi nancial or transactional issues are all fertile ground for meaningful and productive customer-improvement projects. It often helps to have a common language for framing issues. The process-improvement tools that have become increasingly widespread in recent years provide that common lan-guage and framework.

Introduce Concepts CarefullyAs you take these new methodologies to your customers, most of them will not be familiar or experienced with the tools. It is important to ensure that they are properly trained in the concepts. Only when your customers have a strong comfort level with the tools you are asking them to adopt can

they buy-in, become engaged, and embrace the concepts and methodology fully.

Help Customers Own the Project and Follow ThroughPresented in the proper manner, the cus-tomer likely will see benefi ts in undertak-ing the project and will value its outcome. Without someone owning the project on the customer side though, it may be des-tined for certain failure. Therefore, just as with internal projects, it is crucial to have a champion on the customer-side to promote and carry the project through the organi-zation. The higher that person is within the customer’s organization, the better.

Finally, the customer must possess a set of follow-up measures that will maintain the process-improvement momentum for the long-term. It must be their responsibility to implement the improvements and consis-tently do follow-ups to maintain the gains.

Conclusion What do we know about the value of global process improvement efforts for customers thus far? Experience has shown two pri-mary benefi ts: strengthened customer rela-tionships and growth. It is logical that the fi rst would lead to the second. Satisfying our customers is why we are here. SMT

Evelyn A. Baldwin is an SMT Advisory Board member and sales manager for 3M Electronics. Evelyn has been an SMTA member since 1988, and has 20 years of experience in the electronics industry as a material supplier. She also has served one three-year term as vice president of communications at the SMTA. She may be contacted at (978) 886-9661; e-mail: [email protected].

“I think we also would

agree that as the

global business climate

becomes more complex

and interconnected, it

is increasingly diffi cult

to satisfy the customer.”

Four Ways to Help Customers Improve Global Processes

iNEMI will host workshops on April 5, 2006,

in Munich, during SEMICON Europa, and

June 26–30, 2006, in Shanghai, China.

For information, contact Chuck Richardson

at [email protected].

iNEMI International Workshops



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Speaking ofComponents


C R A I G H U N T E R

The Impact of RoHS on Military and Aerospace Applications

his year it happens. By July 1, 2006, all electrical and electronic items (as defi ned by RoHS) available in Europe will be required to comply with low-ppm levels for six restricted

substances. The major impact is the limit of 1,000 ppm applied to lead content, as this requires a wholesale change to electronic PCB soldering processes and materials.

Major OEMs worldwide have managed this change surprisingly well. There still are challenges for manufacturers of mission-critical products arising from two trends of lead-free production. First, commer-cial assemblies need to transition to lead-free. Second, the refl ow medium will typi-cally be based on SnAgCu (SAC); therefore, components must be compatible with this material and must retain reverse-compat-ibility with tin/lead systems that have not yet converted. The ideal, low-cost termina-tion material for passive components meet-ing the above requirements is matte-tin.

While SAC systems provided acceptable performance for many years through a range of applications, they have not yet established the years of history for stress and creep that traditional tin/lead systems have. Another issue is that tin-plated components, whether refl owed in SAC or tin/lead, will have small areas of exposed tin that can cause concern

about whiskers. As studies con-

tinue, many avionic end products will be able to claim an exemption until at least 2010 for the conversion process.

How and where the exemptions are applied will form a key part of manufacturers’ sourc-ing strategies — and all of this is being driven at the component level. Let’s consider two aerospace manufacturers:

• Aerospace Manufacturer “A” has adopted a green, lead-free policy to maximize usage of commercial off-the-shelf (COTS) prod-ucts with no diminishing material supply (DMS) concerns.

• Aerospace Manufacturer “B” will retain usage of MIL components with tin/lead terminations.

Manufacturer “A” has an in-house PCB assembly, external contract electronic manufacturer (CEM) programs, and uses COTS system-level solutions (power sup-plies, VMEs, and displays). Manufacturer

“B” does as well. Manufacturer “A” has some joint programs in which it acts as the con-tract electronic manufacturer (CEM) for Manufacturer “B”, and others where it is an integrator of manufacturer “B’s” systems, and vice versa.

Clearly, there is no one-size-fi ts-all solu-tion, especially as joint programs run the gamut from commercial avionic programs to satellites. All solutions will need to be program-specifi c. Depending on end-cus-tomer requirements, a given program may not be able to use matte-tin-plated com-ponents. This will not be an issue for MIL products, which retain tin/lead termination specifi cations. However, for COTS parts, alternatives such as tin/lead, gold, or pal-ladium silver may be necessary. If the pro-gram has elected to use COTS components, it should be noted that recent technologies have incorporated matte-tin termination since its inception, and a special terminated version may be needed from the supplier. If the program is mission-critical enough to require tin/lead-terminated parts, it may be worthwhile to source an established reli-ability version of the same part.

This is happening now, with suppliers offering established reliable versions of new technologies, and generating new MIL specifi cation sheets for extended range and low-ESR tantalum chips, for exam-ple. It will now be key for the design engi-neer using COTS parts in mission-critical

applications to specify the termination fi n-ish for the component. There will need to be some changes in terminology too. One example is the case of tinning the leads of a thru-hole component.

Traditionally, tinning would mean dip-ping in tin/lead solder. Now, with the commercial part likely to have 100% tin-plated leads, the term itself will cause con-fusion, requiring exact defi nition of the solder composition into which a part is dipped. To avoid confusion from such semantics, for thru-hole parts it is best to source the exact lead fi nish required directly from the supplier. For surface mount passives, it is much more impor-tant — not just a case of semantics, but one of reliability. Dipping a surface mount passive in a tin/lead bath to cover a tin fi n-ish can lead to reliability issues and will negate any suppliers’ part warranties.

For COTS subsystems (off-the-shelf power supplies), the trend will be to have tin-termination passives refl owed in either SAC or tin/lead, depending on the manufacturer. The combination of matte-tin termination in tin/lead has been the staple of the industry for a number of years. But mitigation studies now are performed to allay any concerns with this option, and include supplier’s test results on the potential for whisker generation under certain environmental conditions, how close the component is to an adjacent part or cas-ing, what (if any) coating is used on the PCB, and whether or not the device will be used in a vacuum.

With regard to RoHS compliance, there is one silver lining for users of COTS parts in tin/lead refl ow systems — passive tech-nologies have raised the bar for thermal resistance in that they can withstand mul-tiple cycles of higher temperature refl ows required for SAC systems. Using these parts in tin/lead systems will generate lower stress, and can prove more forgiving in low-volume/high-mix programs. SMT

Craig Hunter is an SMT Editorial Advisory Board member and strategic marketing manager of AVX Corp. in Myrtle Beach, SC. Contact him at (843) 946-0601; Fax: (843) 626-5814; e-mail: [email protected].

“There are challenges for

manufacturers of

mission-critical products

arising from two trends

of lead-free production.”

T



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120

160

200

80

40

0D

1.10

1.20

1.00

0.90

NOSAJ J F A

2004 2005

M A M JJ

Book-to-Bill ratio(based on 3-month rolling average)

Booking indexShipment index

O DNS

1.04

0.96

1.08

1.15

1.051.051.08

1.04

1.101.13

1.06

1.00

1.03

1.131.16 1.16

1.18

1.13

newsCompiled by SMT Staff


the inside line

Book-to-Bill Ends 2005 on Positive Note BANNOCKBURN, Ill. — The IPC IMS/PCB book-to-bill ratio for December 2005 dipped slightly, but remained positive at 1.06. IPC reports the book-to-bill for rigid PCBs was 1.09, while the North American fl exible circuit book-to-bill ratio dropped to 0.95. For these segments combined, sales billed (shipments) for Decem-ber 2005 increased 13.8% year-over-year, and orders booked increased 20.4% from December 2004.

December’s overall book-to-bill remained positive, and combined orders booked for December 2005 increased 20.4% compared to this time last year.

PCB BOOK-TO-BILL RATIO

Get ready for nanotechnology to move from the lab to the marketplace. Though there is still too much hype surrounding nanotechnology, a few practical products from sportswear, to sensors, and even golf balls are available now.

On January 17, 2006, Buffalo, N.Y.-based NanoDynamics Inc. offered a sleeve of their new golf balls engi-neered with nanopar-ticles to every golfer in the annual SMTA Pan Pacifi c Golf Outing at the Hapuna Golf Course on the Big Island of Hawaii. On this Arnold Palmer-designed course, 700' above sea level, each shot had to be precise just to keep the ball on the fairway — rather than in surround-ing lava rock. The wind whipped every drive. Rain sprinkled down on golfers at one point.

“Did the NDMX balls make a dif-ference in my game?” asked the win-ner, George Toskey of Midland, Mich-igan-based Dow Corning Corporation.

“They did seem more controllable than normal, holding the direction better.”

A nanometer, a billionth of a meter, or approximately the size of ten hydrogen atoms in a row, may be a small amount of material, yet new nano-based products can make a big impact in future devices, such as diagnostic machines, sensors, and even golf balls. For instance, Nano-dynamics has applied its expertise in nanotech processing to reduce the grain size of the metal alloys used in the ball’s hollow metal core. The benefi t of reducing grain size

Nano Golf Balls Straighten Drivesfrom micron- to nano-scale is improved impact strength. Reducing grain size increases hardness and ductility is elim-inated, which is key because ductil-

ity yields less-efficient energy transfer, claims the company. Aerodynam-ically, the hollow metal core is a sphere with its mass carried further from its center, creating a gyro-scope effect. This lower spin-rate results in the ball fl ying straighter with

fewer tendencies for hooks and slices, according to NanoDynamics engineers.

Why is small size so important? When materials are reduced in scale, they often behave differently. Nanoparticles are forecasted to create effi cient fuel cells, fortified trims on fenders, tempera-ture-adjusting sports clothing, and golf balls that straighten drives, putts, and approach shots. For more information on the NDX golf balls from NanoDynam-ics, Inc., visit www.nanodynamics.com or www.ndmxgolf.com.

— Gail Flower



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news


Labeling System Verifi es RoHS Compliance NEWTOWN, Conn. — As part of its “Total WEEE/RoHS Management Solutions (TWRS)” service, TUV Rheinland of North America has released a compliance label for companies to certify products for the RoHS Directive. The labeling aspect is part of the company’s TWRS program, a suite of WEEE and RoHS management services that offer companies assistance in the transition to RoHS compliance — from training and education, to product design and review, test reports, calculation of recovery and recycling rates, and regis-tration within each EU member state.

NPL Conference Sees High Attendance MIDDLESEX, UK — The National Physi-cal Laboratory (NPL) conference, “Man-ufacturing Reliable Lead-free Assemblies,” which highlighted NPL’s lead-free solder-ing research saw sold-out attendance num-bers. Presentations were split into several topics. “Lead-free Components” concen-

trated on three areas: tin whiskers, test-ing for lead-containing terminations, and solderability testing. Other presentations included Lead-free Design, Printing with Lead-free Pastes, Refl ow Soldering of Lead-free Solder Pastes, Lead-free Solder Joint Inspection, and Alternatives to Lead-free Sol-dering. A copy of papers presented at the conference is available at http://www.npl.co.uk/ei/clubs/051208sstc.html.

Valor Expands Latin American Business UnitFOOTHILL RANCH, Calif. — As part of a global expansion strategy, Valor Comput-erized Systems appointed Dante Domin-guez as general manager for Latin America. Dominguez will be responsible for build-ing and maintaining relationships with Valor’s customers across Latin America.

FlexLink AB Names CEOGÖTEBORG, Sweden — FlexLink AB will appoint Mattias Perjos to CEO follow-ing Fred Jönsson’s departure in mid-April. Jönsson will become CEO for the Craw-ford Group, a division within Cardo AB.

ITW Acquires Tech Spray GLENVIEW, Ill. and AMARILLO, Texas — Illi-nois Tool Works (ITW) and Tech Spray L.P. have signed an acquisition agree-ment in which ITW acquired Tech Spray L.P., a formulator and manufacturer of quality aerosols and specialty products. Tech Spray will remain an independent company under the ITW Contamination Control group. SMT

calendarMarch2006 Borderland Tradeshow14-15El Paso, TexasMaquila/Manufacturing Solutions; (915) 771-7061; e-mail: [email protected]; Website: www.borderland.tradeshow.net

Military Technologies Conference14-15Boston, Mass.PennWell Corp.; (603) 891-9267; e-mail: [email protected]; Website: www.miltechconference.com

SMTA Toronto/Advanced Manufacturing Expo29-30Mississauga, ON, CanadaSMTA; (952) 920-7682; e-mail: [email protected]; Website: www.smta.org

AprilNEPCON China/EMT China 20064-7Shanghai, ChinaReed Exhibitions; (203) 840-5402, ext. 5313; e-mail: [email protected]; Website: www.nepconchina.com

Atlanta SMTA Expo20Duluth, Ga.SMTA; (952) 920-7682; e-mail: [email protected]; Website: www.smta.org



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THE ELECTRONICS MANUFACTURING INDUSTRY

IS SEEING INCREASED DEMANDS FOR MATERIAL

TRACEABILITY. TRACEABILITY REQUIREMENTS

ONCE LIMITED TO HIGH-RELIABILITY

APPLICATIONS ARE BECOMING A NECESSITY IN

OTHER SECTORS. OEMS FEEL IT IS POINTLESS TO

REQUEST TRACEABILITY WITHOUT CHECKS AND

BALANCES IN PLACE TO ENSURE ACCURACY. THIS

IS MOTIVATING ASSEMBLERS TO ERROR-PROOF

TRACEABILITY SYSTEMS. By Mitch DeCaire

Traceability Data Integrity — Challenges and Solutions

By



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ERPMRP

MES


The electronics manufacturing industry is experiencing increased demands for material traceability. Competitive pres-

sures for improving product quality while reducing cost dictate a higher level of visi-bility and control over the assembly process and materials used. Traceability require-ments once limited to high-reliability appli-cations, such as automotive, aerospace, and medical, are becoming a necessity in other sectors, including data communications, telecom, and high-end computing.

While demanding traceability from EMS providers, OEMs are emphasizing data integrity. They understand it is pointless to request traceability if there are no checks and balances to ensure complete data cap-ture and accuracy. This is motivating assem-blers to error-proof their traceability sys-tems. Smart material-detection systems are replacing manual scanning operations and open-loop systems. Safeguards are being incorporated to prevent production auto-matically, unless the specifi ed traceability data has been recorded successfully. Some factors driving these demands include:Outsourcing. OEMs continue to increase their reliance on the outsourcing model to reduce costs and shift focus to core compe-tencies. These OEMs are concerned with maintaining and improving quality levels because this has a direct infl uence on cus-tomer satisfaction and future revenues. The ability to identify the root cause of a fi eld failure, implement corrective actions, and limit product recalls are considered criti-cal to the success of the outsourcing model. Contractual traceability requirements assure an OEM that its suppliers will imple-ment the control systems needed to gener-ate and collect the necessary data.Product recalls. OEMs are increasingly sen-sitive to the expense of product recalls. When a recall is required, cost and customer impact can be minimized if data exists to identify affected product serial numbers precisely. Without such data, worst-case assumptions must be made when determin-ing which units to recall, resulting in the wasteful and unnecessary removal of good product from the fi eld. Liability. Manufacturing contracts with liabil-ity stipulations emphasize the importance of being able to prove that your products were assembled according to proper customer specifi cations and industry standards, using the correct materials and chemicals. Lead-free. Lead-free conversion schedules vary from OEM to OEM, and by component sup-plier. Some manufacturers will be required to convert certain products to lead-free around specifi c date codes. Others will be tasked

with managing two processes throughout a transitional period, either lead-based or lead-free, depending on where a particular prod-uct serial number will be shipped and sold. All of this presents the assembler with chal-lenges. One constant is that lead-free legis-lation drives the need to know which com-ponents, boards, and solder (bar, paste, wire) were incorporated into each work order or product serial number. Lean manufacturing. Lean initiatives focus on the elimination of waste (muda), error-proofi ng your operations (poka yoke), and increasing material velocity throughout the supply chain. While responding to

customer requirements for traceability, the assembler will simultaneously uncover pro-active opportunities to become lean: • Online material detection systems can

validate that the correct materials and tooling are at required line locations at the right time. This eliminates the cre-ation of scrap (pure muda) associated with line setup errors.

• Material-tracking systems can provide vis-ibility of the status and location of materi-als on the shop floor (Figure 1). This elim-inates wasted time searching for inventory, while enabling precise material procure-ment. You can buy materials confidently based on actual requirements instead of sourcing surplus inventory to compensate for a lack of visibility of components on the production floor.

Moisture-sensitive devices (MSDs). Sev-eral current trends exacerbate the logisti-cal nightmare of MSD control and related risks of moisture-induced defects. Some of these trends include increased sensitivity levels due to higher refl ow temperatures of lead-free; continued reductions in package-body thickness and lead pitch; increased use of plastic over higher-cost, hermetic-body materials; higher-mix production, resulting in longer cumulative exposure time before each tray or reel is consumed completely;

and transfer of manufacturing operations to extremely humid geographic areas.

A material traceability system that accounts for MSD handling relative to the industry standard, IPC/JEDEC J-STD-033B, helps ensure MSDs will survive the refl ow pro-cess. The long-term risk of fi eld failures due to moisture-induced, internal-component damage is reduced. The assembler also gains data that can be used in liability situations to prove that MSDs were managed prop-erly during the assembly process. Such data will indicate that the probable root cause of a moisture-induced defect may be attributed elsewhere in the supply stream.

Defi ning Traceability RequirementsAlthough our industry agrees that material traceability is becoming more important, discrepancy remains as to what this term implies. The defi nition depends on whom you ask. Before selecting a traceability solu-tion, it is critical to understand the depth, scope, and granularity of your customer’s data requirements.

The lowest level of material traceabil-ity, frequently termed item traceability, sim-ply keeps track of work in process (WIP) to maintain time-stamped data on gross-prod-uct movement throughout sequential process steps. Item traceability is deployed in paral-lel with route control to validate that each process step occurred in the appropriate sequence, at the correct workstation or sta-tion type, while confi rming that the product passed all test and inspection points along the way. Item traceability can be performed per work order, but current trends are shifting focus to individual product serial numbers.

Traceability applications necessitate an additional link to the raw materials and tool-ing used during assembly. This can include a history of component lot codes present at a workstation or machine when the product was in it. With the emergence of lead-free, there is an interest in recording raw materi-als, such as solder paste, bar, and wire.

Figure 1. Real-time visibility of materials on shop floor.



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When tracking component lot codes, a traceability system should account for the product’s recipe (machine program or assem-bly instructions) to screen-out online com-ponents that aren’t used on a particular prod-uct. This is especially helpful on assembly lines or stations that incorporate a dedicated setup. In such cases, the presence of a com-ponent on the line does not necessarily indi-cate its use on any particular product.

Within each level of material traceabil-ity is plenty of room for different iterations. When defi ning specifi c requirements, it is important to ask the following questions:• Do we need traceability of all compo-

nents, or just the more-expensive and failure-prone components?

• Are we interested only in devices placed using SMT machines?

• Should we log hand-placements and thru-hole insertions?

• Should we trace lot-code data for other raw materials such as solders, fluxes, and cleaning agents?

• Should we know which operators were involved at each stage of the assembly process?

• Should our system maintain a log of other process parameters, such as stencil serial number, oven-zone temperatures, or the tooling present at a manual workstation?

Full Data Capture and Accuracy “Garbage in/garbage out” is a catchphrase that can be applied to traceability systems. A traceability solution is only as good as the data that goes into it. For this reason, sources of data loss and error should be eliminated wherever possible. A common source of data loss comes from the need to capture each PCB serial number at strategic scan points throughout the assembly process. In such applications, the PCB serial number is

denoted typically by a barcode or 2-D data-matrix symbol. The PCB S/N can be missed due to quality issues associated with the cre-ation and placement of the PCB identifi er, or if scanners along the line are not adjusted properly during product changeover. The risk of data loss is greater in higher-mix envi-ronments with frequent product changeovers, and a variety of PCB form factors.

Product fl ow control can be implemented to control the SMEMA handshake between conveyors and machines at each PCB scan point, and subsequently prevent a PCB from transferring downstream, unless the prod-uct serial number has been captured success-fully (Figure 2). The mechanisms deployed

Figure 2. Product flow control assures data integrity and enforces route control.

TRACEABILITY DATA INTEGRITY — CHALLENGES AND SOLUTIONS



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for product-fl ow control can also be used to prevent further production when a system detects a route-step error, a downstream line setup discrepancy, or a product that failed a prior test step and should not be allowed to progress any further.

Another common error source stems from scanning barcodes manually while materials (components, stencils, solder paste, etc.) are placed at specifi ed locations along the production line. Automated material-detection technologies, commonly termed smart technologies, can replace barcode scanning and eliminate associated human errors. One example, radio frequency iden-tifi cation (RFID), is an emerging material-detection and tracking technology that is garnering much attention.

Tape feeders for an SMT placement machine represent a practical application for RFID. The average PCB assembly fac-tory has made a signifi cant investment in a large number of feeders for different types of components and machines. RFID tags can be attached to each feeder easily and eco-nomically, regardless of feeder type or brand name, to convert any standard feeder into a

smart feeder. RF antenna arrays can then be installed within a placement machine’s feeder banks to detect and identify the feeder at each slot automatically. The system subse-quently prevents assembly defects by validat-ing placement machine setup, and automati-cally collects accurate traceability data during machine setup and replenishment (Figure 3). In addition to improving data integrity, these systems also improve line usage by eliminat-ing the transactional overhead associated

with manual barcode-scanning operations at the SMT line.

RF antenna arrays also can be retrofi tted within off-line changeover banks and feeder storage racks, making it possible to track feeders, including any reels of components left on the feeders, throughout an entire fac-tory (Figure 4). This leads to a more effi -cient production operation. If you know the real-time location of all feeders and reels on your production fl oor, then no time is wasted

Figure 3. RFID tags on feeders, and RF antenna arrays on feeder banks.




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RFID tagAntenna arrays

Feederbank


searching for them. Because you no longer have to compensate for a lack of visibility of shop-fl oor inventory, it is not necessary to purchase surplus components or release more components than necessary from stock. Using RFID technology to validate setup and collect traceability data automat-ically can be extended beyond the placement

machines to any other type of assembly sta-tion. For example, RFID can be used to val-idate that the correct stencil and solder paste are present at a screen printer, or that the cor-rect bin of components resides at a manual assembly station. With these applications, the goal is the same — eliminate ineffi -ciencies and possible errors associated with

human transactions such as manual bar-code-scanning operations.

It isn’t too late for electronics assemblers who have invested in barcode-based MES solutions for setup validation and traceabil-ity. They can still benefi t from RFID tech-nology and automated product-fl ow control without having to replace legacy systems. This is because current and standards-based software integration methodologies, such as Web services, enable interoperabil-ity between otherwise disparate systems. RFID hardware and SMEMA-handshake controllers can be integrated seamlessly with an electronics assembler’s legacy soft-ware system to exchange material-track-ing event data. This type of integration can be applied with internally developed MES or shop-fl oor software systems, or a commercial, third-party MES, as well as software supplied by leading assembly-equipment OEMs.

The most robust traceability systems incorporate a combination of product-fl ow control and automated material and tooling detection at multiple assembly sta-tions (Figure 5). This ensures all specifi ed Figure 4. RFID smart feeders on equipment, off-line banks, and storage racks.


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Manage SMEMA interfaces to control product flow and ensure 100% read rate of product serial number.

RF antenna arrayswithin screen printer.RFID tags on stencils,

paste cartridge, and tooling.

RF antenna arrays within placement equipment.RFID tags on feeders.

Machine/process monitoring

Reflow ovenPick and placeChipshooterPrinter Manual work station


Figure 5. Robust traceability system.

materials are recorded and validated with minimal human intervention before the product is allowed to proceed to the next assembly step or station.

ConclusionTo fulfi ll its intended purpose, a material traceability system should ensure 100% data capture and accuracy. This reinforces the importance of automated data acquisition to eliminate the risk of human error when

possible. A robust traceability system is one that will also prevent production until all required data has been captured, confi rm-ing that the correct materials are at the cor-rect locations at each assembly step for the product being assembled. When a customer demands material traceability from the shop fl oor, it is important to clearly understand the specifi c requirements. When select-ing a traceability system, it is critical to choose a solution that is scalable and open in

architecture to ensure you can react to your customers’ needs, no matter how simple or complex — now and in the future. SMT

Mitch DeCaire, manager, Cogiscan, Inc., may be contacted at (450) 534-2644; e-mail: [email protected].

Cogiscan partners with the following companies:

Equipment OEMsAGS PTE LTDwww.ags.com.sg

Hover-Daviswww.hoverdavis.com

Juki Automation Systemswww.jas-smt.com

IntegratorSchmidtRFIDwww.schmidtrfi d.com

MESAegis Industrial Software Corp.www.aiscorp.com


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Jetting: Dispense Technology of Choice for Adhesives

Many manufacturers choose jetting technology to meet the demands of automated adhesive application processes. As more manufacturers in a variety of industries become aware of its advantages, jetting will become increasingly popular as the dispense technology of choice for adhesives.

By Al Lewis

M any manufacturers today choose jetting technology to meet the demands of their automated adhe-

sive application processes. Companies cur-rently use jetting for corner-attach bond, chip-stack packages (CSP), fl ip chip, no-fl ow, and pre-applied underfi ll applications, as well as conductive, surface mount, UV-cure adhe-sives, and silver epoxy. Because jet technology represents a paradigm shift from needle dis-pensing, it is becoming more popular as the chosen dispense technology for adhesives. Some reasons for this shift include: • A jet dispenses material in smaller spaces

than a needle.• Underfills have smaller fillets with jet-

ting for both BGA and flip-chip on-board applications.

• Jetting is gentle on wire bonds and other delicate assemblies.

• In contrast to jet printers, which are lim-ited, automated jet dispensers can apply specific fluids or viscosity ranges.

• The particular dispense characteristics of adhesives and the range of adhesive appli-cations makes jetting attractive for high-volume production.

• Jetting is an enabling technology for adhesive dispense on cutting-edge designs.

• Jetting offers low cost of ownership compared to other adhesive dispense methods.

A Jetting PrimerCurrent dispense jetting technology uses a mechanically, electrically, or pneumatically

actuated piston with a ball tip to impel fl uid through a narrow orifi ce at the end of the jet nozzle (Figure 1). Air pressure raises the piston, allowing fl uid to fl ow around it into the nozzle. When air pressure is removed, a spring returns the piston so the ball again sits in the nozzle orifi ce. As the ball re-seats,

it shoots a droplet of fl uid out the end of the nozzle. Adjusting the nozzle orifi ce, air and fl uid pressure control droplet size. Precise heat control at the nozzle maintains fl uid temperature at an optimum viscosity for jet-ting, and reduces variation in production.

Small dots propelled from the jetting mechanism at rates up to 200 Hz in four soft-ware-controlled modes: distance-based, time-based, fi xed number of dots per line, and continuous line with breaks, enable the con-struction of many different sizes and shapes of dots and lines. Because the momentum of the fl uid comes from the jetting action, prox-imity to the substrate (dispense gap) is less critical than needle dispensing.

A complete technical description of jetting best illustrates its advantages over other dispense technologies, but even this brief introduction to the fundamentals of jet dispensing reveals several advantages over older adhesive dispensing methods.

Jetting is VersatileMost adhesives that can be dispensed using a needle can be applied with jetting technology. An adhesive can be defi ned as any material that bonds two previously discrete items so the resulting bonded assembly can operate within the range of thermal and mechanical stresses that can be expected within the product’s use.

Using this defi nition, many dispense processes may be understood to be adhe-sive applications. Some processes, such as die attach and stacked die, are obvi-ous. Others, such as underfi ll or lid seals, may not be as obvious, but from the per-spective of the dispense process, represent adhesive applications.

The inherent simplicity of the jetting mechanism enables it to adapt to a wider variety of adhesive fl uids, dispense patterns,

Figure 1. A pneumatic piston impels fluid through a narrow orifice at the end of the nozzle.



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and circuit board geographies than is pos-sible with a needle dispenser. This simplic-ity facilitates multiple adhesive application processes using a single jetting dispenser.

Jetting is Faster for AdhesivesThe most attractive feature of jetting with regard to adhesives is increased speed. The primary reason jetting is faster than needle dispensing is the reduced amount of mechanical travel required by the jet mechanism.

The accumulated speed advantages of jetting are summed up with the phrase

“jet on the fl y.” Speed is the most obvi-ous advantage of jetting adhesives, but the elements of jetting that generate greater speed also create other advantages.

Jetting is Non-contact DispensingTo operate at high speeds, an automated nee-dle dispenser often requires a standoff to pro-vide dispense-gap feedback to the operating system. This contributes several potential negative outcomes:1. Contacting the substrate with every dot

will abrade the tip of the standoff post. This can cause process anomalies and downtime for equipment maintenance.

2. The standoff post can track small amounts of previously applied material onto other parts of the substrate.

3. Because the standoff post sometimes contacts previously applied material, it must be cleaned. This adds complexity to the mechanical and software compo-nents of the dispense process.

4. Contact of the standoff post can damage the board or substrate and knock com-ponents off a PCB.

5. Under-board support typically is required, adding cost and setup time.

Jetting eliminates these possibilities from the process.

Applying Adhesives into Small SpacesSeveral factors restrict the amount of usable space available for a dispensing needle. Rapidly decreasing component size and shrinking real estate for place-ment challenge the capability of needle dispensers to apply adhesives quickly, ac-curately, and effectively. These limits are just as pronounced with screen-printing technology. Some examples of applica-tions where jetting technology’s ability to apply adhesives into tight spaces are:

• SMT applications where it is neces-sary to apply surface mount adhesives to an assembly after solder paste has been applied. Because of the jet nozzle’s ability to fi t into tight spaces, and because it can

build up a dot quickly by applying many shots in the same location, surface mount adhesive can be applied after solder paste without disturbing the paste (Figure 2).

• 0402 component attach, where volumes of 10 nl and dots as small as ~13 mil are pos-sible with jetting;

• Jetting through RF shields for BGA underfi ll;

• Jetting in cavities for MEMS assembly;• Jetting underfi ll on boards with tight

keep-out areas or to jet between closely spaced die (currently as tight as 350 µm).

Jetting as an Enabling TechnologySome of the latest designs in electron-ics packaging, medical devices, and tele-communications equipment make jet-ting an enabling technology — without which the manufacturing of these prod-ucts would be impossible or too expensive to be marketable. Not only does jetting enable the manufacture of these products, it often can be accomplished using stan-dard jetting equipment rather than cus-tom-designed machines.

Typical applications in which jetting can enable untenable designs include die attach, assembling stacked die, produc-ing cell phones that have an RF shield, and installing UV gaskets for LCDs. The speed improvement mentioned above can be as great as 1.5–6× with jetting.

A more vital consideration in favor of jet-ting adhesives for die attach, for example, is the ability to create patterns not possible with a needle dispenser. Another applica-tion that demands the unique patterns avail-able with jetting is dispensing 3-D lines of silver epoxy onto MEMS sensors.

Jetting is Cost-effectiveSeveral features of jetting technology lend themselves to cost effi ciencies not achiev-able with other dispense methods. Jet dis-pense can produce a smaller wetted path than most pumps used for needle dispens-ing. Therefore, less fl uid is wasted. Fewer machines are required with this technol-ogy because one model can handle multi-ple applications. Also, fewer moving parts mean fewer breakdowns, lower mainte-nance, less downtime, and fewer consum-ables. Jetting’s ease of use requires less operator training. Jetting is non-contact dispensing, so it does not require under-board support. Lastly, cleaning requires minimal tools, and can be accomplished in ten minutes or less.

Conclusion Increasing demands of the global manufac-turing market for speed, accuracy, ease of use, and cost effectiveness in adhesive dis-pensing makes jetting technology more attractive than other dispense choices. In response to the demand for enhanced vol-umetric repeatability, one vendor* devel-oped a feature that aims to improve pro-cess capability (Cpk). Dispense patterns are programmed with a specifi ed weight, the system samples the dispense weight per shot periodically, and then computes the num-ber of shots for each pattern. This informa-tion is used to optimize line-speed based on maximum-specifi ed shot intervals.

Jetting is used in the assembly and pack-aging of cell phones, computer processors, MEMS devices, hybrid circuits, and a vari-ety of surface mount PCBs and fl ex circuits. As designers become more familiar with the capability of jetting, they will design parts that can only be manufactured by use of jetting technology. Those that don’t take advantage of the technology lose an oppor-tunity to improve their products. SMT

For a complete list of tables, please contact the author.

*Calibrated Process Jetting (CPJ), Asymtek.

Al Lewis, director of application engineer-ing, Asymtek, may be contacted at (760) 431-1919; e-mail: [email protected].

Figure 2. Jetting technology enables surface mount adhesive to be applied after solder paste without disturbing the paste.

JETTING: DISPENSE TECHNOLOGY OF CHOICE



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After soldering After 4 weeks climatic changes

Inert resinlayer

Organic acidCracks


By Umut Tosun, M.S., Ch.E, and Harald Wack, Ph.D.

We all are experiencing new techno-logical advances, on personal and professional levels. Most consumer-

based products have adapted a true no-clean strategy, primarily due to advancements.

No-clean products offer paste-specifi c advantages that have found broad applica-tion among high-end electronics industries such as aerospace, avionics, and military and defense. Within these markets, no-clean pastes must be cleaned to eliminate any impact of the low-residue nature, according to J-STD-001, Class 3. The term “no-clean” was chosen as a synonym for achieving iden-tical product quality at lower overall process cost by eliminating cleaning as an integrated process step. Often, products manufactured with a no-clean label are not a guarantee for long-term reliable assemblies.

The missing link between in-fi eld-failure rates and climatic and leakage-current mea-surements for electronic assemblies have yet to be established. Actual weather conditions are unfortunately not adequate to simulate in-fi eld conditions, and existing micro-cli-mates at particular assembly locations are infl uenced by site-specifi c factors. The doc-umentation of micro-climatic conditions for electronic assemblies has only recently been possible due to newly developed sensor tech-nologies. Consequently, there is a lack of

available information at this time. In the past, such efforts have been seen in the automotive sector, particularly in areas plagued by high failure rates, such as electronic switches.

Studies on the long-term behavior of no-clean encapsulations show that the integrity of such fi lms can be compromised (Figure 1). This phenomenon depends on the quality of

encapsulation during the soldering step, as well as the degree of actual in-fi eld temper-ature fl uctuations (cycling). Some resin sys-tems also become brittle through oxidation reactions, and therefore guarantee protec-tion for a limited period (Table 1).

HDI assemblies, particularly in motor vehicles, are used more frequently. The use of high-resistivity components accen-tuates the sensitivity of these circuits to

environmental interferences. High-fre-quency circuits between 30 MHz and 5 GHz are particularly affected. To maintain signal integrity, these systems require not only an adequate ohmic-insulation resis-tance, but must also have stable, complex impedance. Parasitic capacitances of con-tamination can distort the ramp-up of the

signal, disrupting integrity and leading to equipment malfunctions (Figure 2).

Proof of CleanlinessReductions in SIR and capacitive potential that activator residues can build up can be shown qualitatively under a scanning elec-tron microscope (SEM). Imaging such contamination is possible using a test that responds selectively to carbon-acid-based

Most consumer-based products

have adapted a true no-clean

strategy, primarily due to rapid

technological changes within the

market. This study illustrates

that products manufactured

using a no-clean label are not a

guarantee of long-term reliability,

demonstrates the impact of this,

and highlights advantages of fully

integrated cleaning processes for

no-clean products.

Figure 1. Encapsulation of organic activators.

Analyzing the Debate of

Clean vs. No-clean



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Go from empty to full without

spending a dime.

Receive a free tank full of 3M™ Novec™ Engineered Fluids.

*This offer is subject to certain limitations and conditions and expires June 30, 2006.

Normal connectionHigh-frequency connection

Inductivity

Capacity


activators. Another direct measurement to determine resistiv-ity values (i.e. of remaining no-clean residues) can be performed through impedance spectroscopy. The surface resistance under-neath chip resistors and capacitors can be determined to show the improvements cleaning provides with respect to surface resistiv-ity (Figure 3). For example, during studies, impedance was mea-sured on identical components on fi ve assemblies. These tests were repeated after the cleaning process. Measurements matched, indi-cating a high level of cleanliness across all assemblies.

This test, in conjunction with other reliability tests, allow assem-bly behavior to be determined under appropriate climatic conditions to assess the overall benefi ts cleaning might have on products.

Post-soldering applications, such as the use of protective con-formal coatings, should also be included in the clean vs. no-clean manufacturing process discussion. During studies, delamination and electrochemical migration were documented underneath coatings up to 0.4" thick. Consideration must also be given to increasing bleed from within assemblies and components. This can limit the long-term adhesion of coatings and underfi ll materi-als. Unfortunately, these critical precipitations are undefi ned, dif-fi cult to characterize or predict, and not monitored. Deteriorated signal integrity will not be explainable or reproducible.

The no-clean process ideally should encapsulate all soils and residues (or evaporate all critical compounds during soldering) to render them ineffective against corrosion and leakage currents. On the other hand, these hardened fi lms can affect the ability for IC testing (Figure 4). The defect rate of IC measurements decreased signifi cantly with a proper contact on residue-free sur-faces. Furthermore, these fi lms often lead to faulty measurements. Contaminated test needles increased needle wear-and-tear, which contribute adversely to overall process costs related to cleaning.

The presence of remaining no-clean fl ux residues also can impact visibility, especially during the automated inspection of soldered connections where various refl ections and contrast impairments are a concern. A lower defect rate (i.e. less rework) is achieved with the use of clean processes.

Introducing a cleaning process for the removal of no-clean fl ux residues adds to equipment and cleaning-agent costs. Such expenses, can be justifi ed when compared to various cost contrib-utors of a no-clean process. For many electronic manufacturing companies, the consumption of nitrogen (even for modern oven systems) refl ects one of the main consumable cost contributors for no-clean processes. In light of lead-free, using nitrogen will be less expendable with promoted oxidation due to higher sol-dering temperatures.

Cost and reliability considerations aside, other benefi ts point to an integrated and stable cleaning process. Soldering serves

Figure 2. Infl uence of high frequency on complex-resistance boards. Flux activator residues can change the impedance of connection surfaces and cause pad geometry enlargements.



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Frequency (Hz)(Uncleaned)

Impe

danc

e (Ω

)

Phas

e (°

)

1 103 10030 1K300

100K

10K

1K

100

10

30K

0

-15

-30

-45

-60

-75

-90

3K

300

30

2wack 1-1Measure

3wack 1-14wack 1-15wack 1-1

Frequency (Hz)(Cleaned)

Impe

danc

e (Ω

)

Phas

e (°

)

1 103 10030 1K300

100K

10K

1K

100

10

30K

0

-15

-30

-45

-60

-75

-90

3K

300

30

wack Nr 2Be 1-2Measure

wack Nr 3Be 1-2wack Nr 4Be 1-2wack Nr 5Be 1-2


Figure 3. Detection of contamination by means of impedance spectroscopy.

ANALYZING THE DEBATE OF CLEAN VS. NO-CLEAN

to create soldered and reliable connections. The addition of a cleaning-process step introduces additional fl exibility through

activated solder pastes and/or fl uxes. This results in an extended soldering process window, i.e. shorter soldering profi les and

improved tolerances for process fl uctua-tions. Aside from appropriate soldering conditions, cleanliness levels of assem-blies must be considered as the second pri-ority for no-clean processes. In compari-son, methods with an integrated cleaning process allow for more freedom. Here, the functionality of each process step that increases the output and reduce superfl u-ous rework steps is important.

For Class 3 products, the J-STD 001D stipulates optical cleanliness (20–40×), as well as a rosin content of <258 µg/in2. Ionic contamination values of <10.06 µg/in.2, SIR conformance, and other cleanliness stan-dards are also required. With lead-free, higher amounts of activators and rosins are used, rendering the J-STD001D confor-mance more diffi cult to achieve without a fully integrated cleaning process. An over-looked benefi t of a clean process is the elim-ination of any material specifi cation with regard to the actual (no-clean) remaining

TABLE 1

Summary of No-clean RisksFull encapsulation ➞ Refl ow process fully optimized.

Partial encapsulation ➞ Hygroscopic residues will absorb moisture.

Electrical cleanliness ➞ Leakage currents, corrosion, electrochemical migration,

and bit failures with RF assemblies (impedance-related).



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contamination. By taking advantage of an integrated cleaning process, companies profi t from reduced costs and failure rates. This process would result in overall improvement of adhesion of conformal coatings and wire bondability.

Conclusion With the onset of globalization movements, cost and logistical con-siderations are becoming more prominent for domestic manufac-turing companies to remain competitive. No-clean processes have not only proven themselves effective, but will continue to play an important role. With more experience and knowledge being gath-ered, we are witnessing numerous high-quality assembly producers reverting to cleaning. The overall benefi t of cleaning can realized

only by studying the positive effects on production costs, product quality, and long-term climatic reliability. Cleaning also is becom-ing a requirement due to the increased occurrence of high-fre-quency technology and the introduction of lead-free solder pastes. Due to the shortcomings of no-clean technologies, the debate of clean vs. no-clean results in one conclusion — cleaning is neces-sary for critical, highly valuable applications. SMT

For a complete list of references, please contact the authors.

Umut Tosun, M.S., Ch.E, application technology manager, Zestron America, may be contacted at (888) 999-9116; e-mail: [email protected]. Harald Wack, Ph.D. is the executive vice president and CEO of Zestron.

Figure 4. Contaminated IC needles showing conventional flux residues (left) and lead-free flux residues (right).

ACL StaticideElk Grove Village, Ill.(847) 981-9212 www.aclstaticide.com

AGC Chemicals Americas, Inc.Mission Viejo, Calif.(949) 348-9608 www.agcchem.comSee Ad on page 16

Aqueous TechnologiesRancho Cucamonga, Calif.(909) 944-7771 www.aqueoustech.com

Austin American Technology Austin, Texas(512) 335-6400www.aat-corp.com

Cookson Electronics Providence, R.I.(203) 799-4904www.cooksonelectronics.comSee Ad on pages 4–5

ITW ChemtronicsKennesaw, Ga.(770) 424-4888www.chemtronics.comSee Ad on page 29

JNJ Industries, Inc.Franklin, Mass.(508) 553-0529www.jnj-industries.com

KesterDes Plaines, Ill. (847) 297-1600www.kester.com

Kyzen CorporationNashville, Tenn.(615) 831-0888www.kyzen.com

March Plasma SystemsConcord, Calif.(925) 827-1240www.marchplasma.com

MicroCare Corp.New Britain, Conn.(860) 827-0626www.microcare.com

Nix of America San Jose, Calif.(408) 971-3115www.nixofamerica.comSee Ad on page 23, 34

Petroferm Inc.Fernandina Beach. Fla.(904) 261-2400www.pertroferm.com

Speedline TechnologiesFranklin, Mass.(508) 520-0083 www.speedlinetech.com

SmartSonic Stencil Cleaning SystemsCanoga Park, Calif.(818) 610-7900www.smartsonic.com

SMT DetergentWestlake Village, Calif.(818) 707-3100www.smtdetergent.com

TechSprayAmarillo, Texas(806) 372-8523www.techspray.com

Zestron CorporationAshburn, Va.(703) 589-1198www.zestron.com

Cleaning Equipment and MaterialsHere are just some additional resources related to this feature. For more information, please contact each company directly.

ANALYZING THE DEBATE OF CLEAN VS. NO-CLEAN



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FPO

Solder spread inpact on process

High Sn-content alloys have higher

surface tension forces than

tin/lead alloys.

Lead-free alloys will not spread to

the edges of the pads as well as

tin/lead – potential for cosmetic

defect.

Requires more precise (accuracy

and repeatability) stencil aperture to

PCB pad alignment (process window

narrows).

•

•

•

63/37 alloy Lead-free

Post

-refl

owPr

e-re

flow


Identifying Stencils for Lead-free Solder PasteJuly 1, 2006 marks the era of lead-free electronics in Europe. The infl uence of RoHS and

WEEE will result in better environmental quality, protection of human health, and more

rational use of natural resources. But the removal of lead from electronics will bring massive

changes for all companies in the supply chain.

Beginning with the July 1, 2006 dead-line, all suppliers must make changes to ensure compliance with the lead-

free requirements of RoHS. On the surface mount production line, both OEMs and EMS providers are faced with several chal-lenges with the emphasis on materials and process traceability. The process includes print accuracy and the alignment of the stencil to the PCB. Material changes incor-porate special tooling such as stencils. This will require two stencils for the same pro-duction run because the same stencil cannot be used for both — the lead-bearing stencil will contaminate the lead-free batch.

The lead-free printing process should demonstrate a similar performance as the lead-based paste printing process, i.e. sten-cil life, print defi nition, and repeatabil-ity — provided no density issues exist with the paste. In general, no major changes to the printing process should be required. However, because tin/lead solder tends to have better wetting than most lead-free alloys, some stencil-design modifi -cations may be needed to maximize paste spread and counteract inferior wetting. Depending on the materials and compo-nents used, if wetting is not suffi cient, sten-cil design modifi cations may be needed. For example, rather than producing sten-cils with reductions of the aperture, we may have to look at running the stencil 1:1

with the board. This is a trade-off because going 1:1 with the board may result in more defects during the assembly process. It would be advisable to administer a test run on a current stencil to confi rm acceptable spread and wetting.

Paste Characteristics Due to paste-release characteristics and lower wetting forces, the use of a material

other than standard stainless steel should be evaluated for the lead-free stencil. Materi-als with higher nickel content offer more lubrication (less friction), improving paste release. This material, which is currently used to manufacture stencils for ultra-fi ne-pitch or µBGA, offers better paste trans-fer and volume.

Lack of spreading during the refl ow process requires a tighter process window,

Figure 1. 0603s and 0805s printed with lead-free solder paste before and after reflow. There is a lack of spread during the reflow process. Photo courtesy of Speedline Technologies.

By Holly Wise



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TEMS®

A unit of ND Industries®, Inc.

Low Pressure Injection Overmolding

RuggedizingElectronics

Fromthis

Tothis

www.temsnd.com• Low Pressure Injection Overmolding

• Potting • Sealing • EMI/RFI Shielding • Thermal Management

ND Industries, Inc. • 1000 North Crooks Road • Clawson, MI 48017 USA • Phone: 248-655-2506

• Los Angeles • Dallas • Chicago • Rockford • Detroit • Cleveland • Charlotte • New York • Orlando

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®ND, ND Industries, ND Industries logo, and TEMS are registered trademarks of ND Industries, Inc.

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IDENTIFYING STENCILS FOR LEAD-FREE SOLDER PASTE

making the aperture position on the stencil and the placement of the solder on the pad more critical. Tighter control of reg-istration from stencil to board is mandatory to maximize pad coverage, especially when placing components such as 0402. If the positional accuracy of the stencil is off, it will compound alignment issues (Figure 1).

Inspection and AccuracyWhen using lead-free, it is more important that the positional accuracy of the stencil be verifi ed prior to use. This makes proper inspection procedures a signifi cant feature when deter-mining a stencil supplier that will be a facilitator in the lead-free transition. An automated optical inspection (AOI) system* can be used to ensure positional accuracy and size over the entire stencil. If any of the scanned apertures are misaligned with the Gerber data due to an out-of-focus laser beam or non-calibrated laser equipment, the operator is alerted with a percentage error,

and the misaligned apertures are highlighted. In the lead-free environment, stencil manufacturers will require sophisticated inspection systems such as AOI.

Another method to ease the transition to lead-free is to make lead-free stencils distinguishable from lead-bearing stencils to avoid contamination. In this example, the polyes-ter border between the stainless-steel foil and the standard, white, mesh frame signifies lead-bearing stencils. Lead-free stencils are manufactured using a bright orange polyester border, and the “Pb-free” symbol is etched onto the sten-cil (Figure 2).

Conclusion If lead-free isn’t on your agenda now, it soon will be. With all involved parties ready and equipped to handle the conversion, problems should be minimal. SMT

*LPKF ScanCheck AOI system, LPKF Laser and Electronics.

Holly Wise, technical accounts manager, MicroScreen, may be contacted at (574) 232-4418; e-mail: [email protected].

Figure 2. Lead-free (l) and lead-bearing (r) stencils show distinguishing marks to help avoid contamination.

“Another method to ease the transition

to lead-free is to make lead-free stencils

distinguishable from lead-bearing stencils

to avoid contamination.”

Pb



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3

LEAD

-FREE

Serie

s


ost joints soldered with lead-free solders exhibit a dull or frosty appearance. This differs

from the smooth, bright, shiny surfaces experienced with tin/lead solders. This is typical of SAC alloys (tin/silver/cop-per) commonly used in lead-free solder-ing applications. There are a number of reasons for this occurrence. One reason is that these lead-free alloys contain three different elements, and thus three eutec-tics, during solder solidifi cation. These eutectics each have their own melting point and solidifi cation behavior.

Formation of Different Eutectic NucleiSolder consists of an alloy that is a mix of two or more metals. The melting and solidifi cation behavior will depend on the formation of areas in the solder where dif-ferent eutectics might solidify. This can be the case when solder contains copper and silver. In this case, CuSn- and AgSn-eutectic parts or eutectic traces can form next to the SnAgCu eutectic during solid-ifi cation of the solder in the joint.

The different eutectics that can be formed in SAC alloys are Sn5Cu6 at 227°C, SnAg3 at 221°C, and Sn+SnAg3+Sn5Cu6 at 217°C. However, this is only true if the total pro-cess contains only lead-free elements. In the case of a tin-rich alloy, tin crystals can pre-cipitate out of the alloy during cooling of the joint at 232°C. If component leads are used with a tin/lead plating, the lead dissolved

from the plating can also introduce eutec-tic traces. This will lower the melting point for some parts of the solder in the joint to 183°C for tin/lead eutectics, or to 178°C for SnPbAg eutectics.

Solder Contraction or Shrinkage While SolidifyingAs the molten solder solidifi es, it will shrink by about 4%. Most of this volume reduc-tion will be found in areas where the solder solidifi es last. These commonly are areas where traces of the lowest melting eutec-tic solder are found. If these traces are at the joint-surface area, this mechanism can create a dull appearance. This 4% volume reduction often can be held responsible for the formation of micro-cracks in the solder joint. If the solder fi llet moves during this process due to pads lifting during soldering, for example, and moves back during cool-ing, these micro-cracks can develop larger cracks due to volume reduction combined with movement. These cracks will be found only at the fi llet surface of the solder joints. The solder in between the copper barrel and the lead generally will make a sound con-nection that will strengthen the joint.

Movement of Soldered Components or Solder While PastyThe movement of soldered parts or solder while not fully solidifi ed or pasty can (at worst) create cracks in solder joints, and (at best) give the solder joint a matte appearance

at the surface. The natural movement of the solder pad during the formation of a solder joint can cause this phenomenon. When multiple joints are spaced together (as with a connector), this solder-pad movement can be considerable, and may cause fi llet tearing, fi llet lifting, or pad tearing.

The differences in coeffi cients of thermal expansion (CTE) between the copper bar-rel that forms the plated thru-hole and the epoxy-based material located between these joints causes this pad movement. As a result, the solder pad will be lifted in a wedge shape from the edges of the copper barrel during contact with the solder wave, and during the fi lling of joints with liquid solder.

As soon as the soldered joint exits the wave, it begins to solidify. Initially, dur-ing this process more heat is transferred to the epoxy/glass board material until the solidifi cation of thermal energy is dissipated fully. Afterward, the board cools and returns to its original dimen-sions. During this time, the wedge-like shape of the solder pad returns to a fl at confi guration again. When this occurs, the solder is not solidifi ed completely and exhibits a pasty characteristic. It is this movement that can disturb the joint surface during joint solidifi cation and can create cracks as a result of com-bined shrinkage and fi llet tearing. These cracks are commonly positioned parallel to the PCB surface. Occasionally, they form a completely circular crack.

M

Matte-fi nish Solder Joints after Lead-free Wave SolderingMOST JOINTS SOLDERED USING LEAD-FREE ALLOYS EXHIBIT A DULL OR

FROSTY APPEARANCE, WHICH DIFFERS FROM THE SMOOTH, BRIGHT,

SHINY SURFACES OF TIN/LEAD SOLDERS. THIS ARTICLE LOOKS AT SEVERAL

REASONS FOR THIS PHENOMENON.

By Gerjan Diepstraten



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Solder Joint AppearanceDuring solidifi cation, the eutectic with the lowest melting point often is surrounded by already solidifi ed particles — the eutectics with higher melting points. This means that during fi nal solidifi cation of the solder joint, a soup of molten solder and already solidi-fi ed particles with a different grain structure is formed. During solidifi cation, the solder volume will shrink by about 4%. Most of this volume reduction and contraction is found on alloy parts in the joint that solidifi es last.

This mix of liquid and solid solidifying at different stages, each with a different surface structure and combined with volume reduc-tion, gives the joint a dull appearance.

Often, all of these mechanisms will act concurrently, but not on every group of joints at the same rate. This explains dif-ferences in surface appearance after solder-ing. Because the source of the dull solder joint appearance lies in the combination of the process and the alloy used, the out-come should be judged as normal. This is

why the dull or matte appearance of such solder joints should be regarded as an effect, not a defect.

Effects of Forced CoolingForced cooling helps reduce the temperature of the PCB at a faster rate, but has no real effect on any of these mechanisms. It can prevent further heat build-up in components from the dissipated solidifi cation heat com-ing from the solder joint directly after sol-dering — if cooling takes place at the com-ponent side during this stage. Temperature

Explanation of Shrink Structure FormationIf the solder alloy contains ele-ments that can form more than one eutectic alloy, different shrin-kage patterns can be formed, giving the solder joints a rough appearance. Because factors such as solder volume in the joint, the heat-sinking effect of parts invol-ved, alloy composition, and lead plating can affect the cooling of a soldered joint after leaving the wave, solder solidifi cation will not be the same for all joints. This means that joints can have a diffe-rent appearance at the end of the soldering process. Here’s why:

Assume that a given SAC sol-der volume has the exact ternary-eutectic composition Sn3.5Ag0.9Cu. This alloy will have a melting point of 217°C. Under ideal conditions, it has that melting point and no other melting points from the binary eutectics that could also be present in this solder volume. Therefore, this volume of solder will solidify as one homogeneous alloy that is in full equilibrium due to its exact ternary-eutectic com-position and equal temperature. Normally, such an alloy will soli-dify with a smooth surface under these conditions because the sol-der shrinkage will be divided over the volume equally.

Next, assume that extra tin is added to this perfect ternary sol-der mixture deliberately. The extra tin cannot be part of the ternary eutectic because the alloy now con-tains too much tin. This excess tin, which has a melting point of 232°C,

MATTE-FINISH SOLDER JOINTS AFTER LEAD-FREE WAVE SOLDERING



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RRework & Repair

All Chemtronics lead-free products are:Engineered for high temperature lead-free applicationsSpecifically designed for all lead-free solderRoHS compliant

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Contact ITW Chemtronics today for more information about the new Lead-Free productline. Call our technical hotline at 770-832-4401, oremail us at [email protected].

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measurements of solidifi cation behavior of soldered joints have taught us that solidifi -cation for most joints is completed within three seconds after wave-departure time. Any cooling positioned after this has no major effect on the already solidifi ed joint. Forced-air cooling within this three-second interval also cools the solder wave, which is undesired and not recommended. Typical values for reaching the solidifi cation tem-perature using SAC alloys are 1.4 seconds, while the joint is solidifi ed fully 3.2 seconds after exiting the wave.

ConclusionIn lead-free soldering, matte or dull joints are normal and should not be considered defects. Differences in cooling behavior cause differences in dullness or gloss between soldered joints on a board due to differences in the thermal layout of individ-ual solder joints. In a process, equal joints will behave equally and therefore will have the same appearance after soldering. How-ever, joints with another layout, such as larger or smaller holes, different pad sizes,

or other component leads or components, might demonstrate different cooling behavior, resulting in a different joint appearance. Finally, solder composition plays a major role in all issues and results. Forced cooling after soldering does not remedy or prevent dull joints in lead-free wave soldering. SMT

Gerjan Diepstraten is the senior application engineer at Vitronics Soltec. For more infor-mation, e-mail: [email protected].

will precipitate as solidifi ed crystals (dendrites) as the solder cools until the remaining liquid mix has its per-fect ternary-eutectic composition. As this remaining liquid mix conti-nues to solidify at 217°C, the solder shrinks by about 4%. This shrinkage originates with the remaining liquid and not from the already solidifi ed tin dendrites. Final shrinkage will take place at the point where the joint reaches a temperature below 217°C. In most cases, this will be the part that was in contact with the solder wave for the longest time, commonly the joint fi llet at the sol-der side. Thus, the tin dendrite pro-fi le is present primarily at the sur-face of the solidifi ed solder.

In real solder joints, the ideal ternary mix, assuming one begins with such an alloy, will be mixed with metallic parts from the PCB and lead metallization. Parts of these elements will be dissolved into the limited amount of solder that forms the joint. These extra elements will disturb the ideal ter-nary eutectic. This means that the solidifi cation of that solder mix will not be at one temperature of 217°C, but that parts of this mix may already solidify at 232°, 227°, or 221°C. In the event that the com-ponent leads are tin/lead plated, tin/lead eutectic traces or SnPbAg eutectic traces also may be found in the joint, having melting points of 183°C and 178°C, respectively. In most cases, SAC alloys are used with a composition that deviates from the ideal eutectic composi-tion. This might create different eutectics that ultimately generate a rough-joint surface.

MATTE-FINISH SOLDER JOINTS AFTER LEAD-FREE WAVE SOLDERING



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EMST R E N D S C O N T R A C T M A N U F A C T U R I N G


G iven the complicated sup-ply chain, there are sev-eral chances for mistakes and oversight when deal-ing with lead-free com-

pliance. The RoHS Directive will require manufacturers to incorporate measures to ensure all electronic components, cable assemblies, and hardware meet the guide-lines. A percentage of components may not be certifi able by the manufacturer. One component error on a PCB assembly with hundreds or thousands of parts can result in a rejection of product with the poten-tial for signifi cant legal penalties or loss of sales. Manufacturers must take measures to have suppliers verify product compliance, including certifi cation of all parts and cre-ating segregated storage areas. This high risk of non-compliance has driven one company* to institute a program that re-duces the exposure to risk dramatically, while improving documentation to help substantiate compliance.

XRF Technology X-ray fl uorescence analysis is based on the phenomenon of the emission of X-rays by the constituent atoms of a sample when excited by an external source of radia-tion. The energy difference between the two energy shells involved in the process is released in the form of X-ray radiation. We call this radiation a characteristic X-ray because its energy is specifi c and unique to the emitting element (atom).

A practical embodiment of an instru-ment capable of performing those tasks is called an X-ray fl uorescence (XRF) spec-trometer. It consists of three essential com-ponents: a source of exciting radiation (a radioisotope or X-ray tube), a means of reproducible sample presentation, and a detector with a multi-channel analyzer (MCA) and analytical software. During measurement, the instrument acquires an X-ray spectrum of the sample that contains information about its elemental composi-tion. It is the information extracted from

the spectrum that is then converted into qualitative and quantitative data of the elemental concentrations in the material tested (Figure 1).

Verifi cation Program Through screening using a portable, hand-held analyzer, we understand the fi rst phase of testing, during which an assessment is made as to whether additional, more expen-sive, and labor-intensive testing is required. With the deadline for RoHS-compliance approaching, and the entire industry tran-sitioning, many material declarations and certifi cates of conformance programs are being developed to certify RoHS compli-ance. One program was developed to ver-ify the supply chain. This program includes the use of a portable XRF unit** to sup-port the materials declaration process. The program consists of material verifi cation at several locations in the production process. The initial step of this process is incom-ing inspection. This detection point is the fi rst line of defense to verify that a specifi c material is RoHS-compliant (Figure 2).

Two additional detection points are included in the production process. The verifi cation of process-input parameters is critical to the compliance program. Evalu-ation of the assembly process and mapping of critical input and equipment parame-ters will support the compliance program. A failure mode effects and analysis (FMEA)

Due Diligence Verifi cation — Ensuring RoHS Compliance ROHS compliance will require manufacturers to

incorporate measures to ensure all electronic components

meet the EU’s directive. Manufacturers must take measures

to have suppliers verify product compliance, including

certification of all parts and creating segregated

storage areas. This article looks at the program one

EMS provider instituted to document compliance.

By Scott Mazur and David Mercuro

Figure 1. Analyzer display indicating the concentration of five elements: cadmium (Cd), lead (Pb), bromine (Br), mercury (Hg), and chromium (Cr), which are controlled by RoHS. In this test, lead and bromine are at non-compli-ance levels; and cadmium is determined questionable in 30 seconds.



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can be completed. It is important to develop a comprehensive list, as process material and equipment could escape the RoHS-com-pliance analysis, and may introduce one of the banned substances into the assembly process. The XRF unit can be deployed to ver-ify that input and equipment parameters are RoHS-compliant. Some examples of critical process inputs could include solder during a PCB assembly process or adhesive during a mechani-cal assembly process.

The fi nal detection point during the production process is the fi nished product. The goal is to complement incoming inspection and the critical input-parameter process by verify-ing compliance at the fi nal assembly process step. Documen-tation of record retention of XRF results must be maintained to provide proof of the results and a history of compliance. Streamlining the record retention will simplify the process, especially if a request or non-conformance is detected during entry into the EU.

ConclusionInstituting a compliance program strategy enables detection of non-conformance during the manufacturing process where prob-lems can be corrected, rather than during the RoHS-compliance process, which can result in disastrous consequences. Without the XRF-compliance process, electronic manufacturers must depend on supply chain verifi cation and due diligence. The deployment of such a program will provide customers with a verifi cation process, while reducing the risk involved with manufacturing product that will reside in EU member states. SMT

* Benchmark Electronics. ** XLt 797 portable XRF unit, Thermo Electron Corp.

Scott Mazur, RoHS specialist, principal quality engineer, Benchmark Electronics, may be contacted at (603) 879-7000, ext. 8004; e-mail: [email protected]. David Mercuro, XRF product specialist, Thermo Electron Corp., Niton Analyz-ers unit, may be contacted at (781) 670-7460, ext. 333; e-mail: [email protected].

Figure 2. Component analysis is done using a handheld XRF analyzer during the incoming inspection verification process.



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Greater than 60% of end-of-line defects in SMT

assembly can be traced to solder paste and the printing process. Another

15% occur during refl ow. Using designed experiments and the measurement of critical solder paste-related process metrics, a solder paste evaluation procedure was developed

to maximize information about the paste and its processability, while

minimizing experimentation.

step bystepSMT12

76543

910


8

Studies show that more than 60% of end-of-line defects in SMT assem-bly can be traced to solder paste and the printing process.1 Another 15% of these defects occur dur-ing refl ow. Despite this, it is sur-prising that no simplifi ed proce-dure for solder paste evaluation has been documented. With the short time frame available to implement a RoHS pro-gram, there now exists a tremendous need for a simplifi ed and highly effective procedure. Using designed experiments and measuring critical solder paste-related metrics, a solder paste evaluation procedure was developed to increase information about solder paste and its processability, while reducing experimentation.

Using 12 stencil-printed printed wiring boards (PWBs), statistically signifi cant results were generated, allowing the ranking of solder pastes according to performance. Response metrics investigated included print volume and defi nition before and after pause, squeegee hang-up, slump, tack, release from aperture, and solder joint quality.

Solder paste expense represents only 0.05%2 of the value of fi nished electronics, yet it can have a tremen-dous impact on product performance and reliability. Given the importance of solder paste to the fi nal assem-bled product, it is vital to evaluate solder paste perfor-mance in a systematic way. Printability, tack, refl ow characteristics, surface insulation resistance (SIR), solder balling, and wetting form a minimum of sol-der paste performance metrics to consider. Testability and cleanability also may be metrics to assess in certain assembly processes.

PrintabilityA well-shaped printed brick with good volume consis-tency likely is the best predictor of high end-of-line yields. Too much solder paste in the printed brick could result in shorts, whereas too little may cause opens. Setting solder paste volume specifi cations and moni-toring the printing process for conformance to these specifi cations can have the strongest positive effect on yields. An effective way to accomplish such control is a statistical process control (SPC) program that assures

that the control limits of the printed brick volume are within the upper and lower specifi cations.3

Refl ow CharacteristicsMost modern lead-bearing

solder pastes refl ow relatively well. Refl ow performance does

not vary as much as printing per-formance. With lead-free solder pastes,

however, refl ow performance can vary greatly. For lead-free pastes, two refl ow criteria are important:

The paste should perform well in a wide temperature and time above liquidus (TAL) window; post-refl ow — the solder should exhibit good coalescence.4

Due to the concern for components surviving higher refl ow temperatures related to lead-free assembly, more discipline is needed to assure successful refl ow at min-imum temperatures. Figure 1 shows nine profi les for Sn3.8Ag0.7Cu solder paste (Tm=217°C). One solder paste exhibited good wetting and coalescence during refl ow with all nine profi les.4

TackTack is the ability to hold the component on the PWB after placement. Optimum tack holds the component with an acceptable amount of force that does remains consistent over time. Unfortunately, tack will vary with time. A useful rating scheme for tack has been proposed.5

SIR, Solder Balling, Slump, Wetting, and ElectromigrationJ-STD-004 and J-STD-005 (IPC-TM-650) cover a variety of tests related to surface insulation, solder balling, slump, wetting, and electromigration. It is not our intent to minimize the importance of these tests. However, most solder paste companies perform these tests with reasonable integrity, and the informa-tion that the solder paste data sheets provide can be used in a screening process for assessing pastes. After selecting the fi nal candidates in any evaluation process, it may be wise to perform some of these tests on the fi nal candidates yourself.

STEP 3: Solder MaterialsBy Timothy Jensen and

Ronald C. Lasky, Ph.D., PE



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P1 P4 P7

Time aboveliquidus

Time above liquidus

Lead-free reflow profile

Lead-free 2×3 full-factorial reflow DOE• Minimize peak temperature to reduce thermal stress on components.• Interaction between peak temperature and time above liquidus.

Reflow profile matrix

Selected paste must perform equally well at P1 through P9 in air atmosphere

Ramp rate

60sec.

70sec.

80sec.

P2 P5 P8

P3

229°C

237°C

245°C P6 P9

Peak

tem

pera

ture

Peak temp

1. Start with enough paste for 12 prints.

2. Print four boards (no kneading).

Two-hour sit, place,measure tack

Six-hour sit, place,measure tack

One board,one-hour sitthen reflow

One board,three-hour sitthen reflow

Repeat

3. Pause one hour, no kneading, print four more boards, repeat tests in 2.

4. Pause one hour, no kneading, print four more boards, repeat tests in 2.

Metrics to measure• Print volume• Print definition• Volume and definition after idle• Release from aperture• Squeegee hang-up• Tack• Solder joint quality

For final candidates• Coalescence• Reflow window• J standards

The twelve board paste evaluator


Figure 1. Reflow profile matrix.

Proposed Screening Test for Solder Paste Considering the importance of stencil print-ing, and the fact that most paste vendors test and report the results of their pastes for J-STD-004 and J-STD-005 (IPC-TM-650) faithfully, a screening test for printed-volume consistency with visual analysis of print characteristics such as slump, bridg-ing, etc., can quickly separate top paste can-didates from the “also-rans.” One approach was proposed, but it did not include measur-ing printed brick volume.6 It also required printing 27 boards. We propose an evalua-tion process requiring the printing of only 12 boards with print-volume consistency as its foundation (Figure 2).

To follow the 12-board paste-evaluator process, start with enough paste for 12 prints. No kneading is done to the paste prior to printing. Four boards are then printed in Step 1 (Figure 2). No stencil wiping is done during the prints. Print volume, print defi nition, release from aperture, and squeegee hang-up are mea-sured. Two of the four boards sit for two hours, and two of the four boards sit for six hours. Components are then placed. Then tack is measured. One of the fi rst two sets of boards sits for one hour, and one for three hours prior to refl ow. The same procedure is performed on the sec-ond set of two boards.

In Step 2 of Figure 2, the paste is left idle for one hour, and the process in the above paragraph is repeated. In Step 3, the paste is left idle for another hour and the pro-cess is repeated again. For initial screen-ing, the process may stop at measuring print-volume consistency and defi nition. This approach may be reasonable as it min-imizes work, and poor print-volume con-sistency or print defi nition may eliminate a paste candidate.

Paste candidates that do well in printed volume consistency, tack, coalescence, refl ow window size (larger preferred), sol-der joint quality, and the J-STD-004 and J-STD-005 standard tests should be verifi ed. One attribute that this evaluation technique does not consider is a solder paste’s resis-tance to shear thinning. This attribute typ-ically is only important to those high-vol-ume/low-mix operations in which the solder paste is being printed continually with little to no downtime. By design, solder paste is thixotropic in nature, meaning that the vis-cosity drops as shear is applied, and viscos-ity recovers when that shear is removed. In stencil printing, the squeegee blade imparts shear on the paste and lowers the viscosity, allowing it to fi ll stencil apertures better. At

the end of the print stroke, the bead of paste recovers to its original viscosity. Contin-ual printing overcomes some solder pastes’ recovery capabilities and does not allow suf-fi cient time for their viscosity to recover. If this occurs, that solder paste will gradually become lower in viscosity, resulting even-tually in slumping and bridging of its print deposits. To assess this phenomenon, sev-eral boards must be printed. However, it can be simulated by running the stencil printer’s knead function 50–100 times. Print depos-its following this knead cycle should be inspected for print volume and visual print brick shape.

An analysis of three no-clean pastes was conducted to see how they performed using

the 12-board paste evaluator. We printed through a 6-mil stencil using apertures for a 208-pin, 0.5-mm QFP. Twenty apertures were used for measuring the print deposits, and the average volume of the apertures was 7,968 mil3. The printed volume consistency yielded striking results (Figure 3). Each data point represents (for each print num-ber) the average paste volume of the afore-mentioned 20 aperture sites.

As we see from Figure 3, the print-vol-ume consistency of Paste 3 is poor. It var-ies from about 5,400–9,050 mil3. It also shows an unacceptable response to pause, the fi rst printed volume decreased signif-icantly after each one-hour pause. The average of this paste was 8,206 mil3 (or an

Figure 2. The 12-board paste evaluator.



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10,000

9,000

8,000

7,000

6,000

5,000

4,00014121086420

Paste volume vs. number of prints

Volu

me

of d

epos

it (c

ubic

mils

)

Print number

Paste 3

Paste 2

Paste 1

One-hour pause


Figure 3. Paste volume vs. number of prints.

average transfer effi ciency [TE] of 1.03), and the standard devia-tion was 1,047 mil3. Paste 1 was the most consistent with an aver-age of 8,616 mil3 (average TE of 1.08), but with a relatively low standard deviation of 279 mil3. Paste 2 fi nished second with an average printed volume of 8,745 mil3 (average TE of 1.10), and a standard deviation of 485 mil3.

Most SPC programs set control limits to ±3 standard devia-tions. Using these criteria, the best performer, Paste 1, would have control limits of 8,616 ±837 mil3, or less than ±10%. Typ-ically, solder paste volume control of ±20–30% is needed. With

these criteria, Paste 2 would still be a candidate at 8,745 ±1,455, or ±16.6%. From a screening perspective, we have eliminated one paste and can devote our resources to evaluating the other param-eters for Pastes 1 and 2. In addition to print-volume consistency being the most important solder paste metric, it also may be the most variable among solder pastes. Therefore, using it as the fi rst criteria can save time in screening pastes.

Voiding: A Greater Concern for Lead-free?In a study conducted on the voiding of lead-free solders,7 it is clear that the higher molten surface tension and poorer wetting of lead-free increases the potential for voiding compared to tin/lead processes. Given this increased voiding, the question becomes whether this will impact product performance and/or reliabil-ity. The IPC Solder Products Value Council (SPVC) concluded that there was no direct correlation to quantity and size of voids and thermal-cycling reliability in products tested.8 This means that simple X-ray analysis is not suffi cient to estimate a prod-uct’s reliability.

One scenario in which the increase in voiding may have a dra-matic impact is in products that use µBGAs or chip-scale pack-ages (CSPs) with microvia-in-pad technology. Because of the increase in lead-free voiding, it is possible that two adjacent balls could bridge and short if both have large voids. This phenomenon could create a signifi cant increase in rework of costly components. Because optimizing the refl ow profi le can reduce this voiding, the importance of the profi le window portion of the solder paste eval-uation is critical when selecting the ideal solder paste.

Conclusion A 12-board solder paste evaluator is proposed. Although the solder paste evaluator includes all important solder paste evaluation crite-ria, solder paste print-volume consistency is the fi rst to be evaluated. Due to the fact that solder paste print-volume consistency is the most important criteria for high end-of-line yields, this fi rst part of the 12-board evaluator can be used as a screening test. SMT

The authors would like to thank Professor Daryl Santos and Aniket Bhave for their contributions to this article.

REFERENCES1 Jensen, Timothy, “Solder Paste Printing and Refl ow” workshop, 2003.2 Lasky, Ronald, “An Overview of the Electronics Industry,” 2003.3 Lasky, Ronald, “SPC Workshop,” 2003. 4 Goudarzi, Vahid, “Lead-free Workshop,” Plantation, FL, 2003; contact [email protected] for a copy of the proceedings.5 Lee, Ning-Cheng, “R&D Test Requirement for Solder Pastes,” Indium

Corporation, 2003.6 Herber, Rob, et al., “The 27 Board Challenge,” presented at SMT

workshop, Toronto, Canada, 1998.7 Jo, Hyoroon, et al., “Voiding of Lead-free Soldering at Microvia,”

SMTAI, 2003.8 “The Effect of Voiding in Solder Interconnections Formed from Pb-

free Solder Pastes with Sn/Ag/Cu.” This paper is available for down-load at www.ipc.org.

Timothy Jensen, product specialist, Indium Corporation, may be contacted via e-mail: [email protected]. Ronald C. Lasky, Ph.D., PE, senior technologist, Indium Corporation of America, may be contacted via e-mail: [email protected].

SMT 101: SOLDER MATERIALS



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...know the difference

VectorGuardTM

We’re already there.

DEK’s VectorGuard™ stencil system has been developed to lighten your load and keep things simple.

The high performance frameless foils are easier to manage than standard,permanently-mounted stencils. They are lighter, using finer materials. There are no sharp edges, making handling safe and changeovers quick. Tensioning andadjustment is done automatically, and mounting the foils in the VectorGuard frame couldn’t be easier.

For peace of mind, rigid construction protects the stencil body during handling, transitand storage, and foils can be washed as soon as they are removed from the frame.

The VectorGuard system also solves storage challenges.Stencils are hung in a convenient cabinet, taking up just a quarter of the space needed to house conventionalfoils. Re-usable VectorGuard frames save you the timeand cost of sending frames back to your supplier forrefurbishment. And after use, the plastic corners andaluminium edges are easy to separate from the steel foil,allowing each material to be recycled.

Sometimes, the simplest solutions are the most complete.

DEK USA Inc. 8 Bartles Corner Road, Flemington, NJ 08822, USA

Tel: +1 908 782 4140 Fax: +1 908 782 4774

Internet: www.dek.com



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productsn e w

Cleaning Materials & Equipment

Stencil CleanerSMT USC400 is a portable, ultrasonic-contact-type stencil cleaning system. The transducer in the hand tool vibrates contamination through small stencil apertures, and residues are collected on a disposable-wipe material under the sten-cil. The system can remove diffi cult high-tack residues, such as those from lead-free solder materials. Suitable for off-line and on-printer cleaning operations, stencil cleaning can occur on the printer without removing the stencil frame. An optional ultrasonic mini-bath is also available, allowing cleaning of placement nozzles, glue-dispensing needles, and test probes. Surclean, Cowes, Isle of Wright, England, www.smt.uk.com.

COMPONENTS

Surface Mount Chip ResistorsThe Super RCX series thick-fi lm, wrap-around, surface mount chip resistors eliminate the need for re-design to accom-modate higher power, while maintaining

resistor size and footprint. Avail-able sizes include 0402, 0603, 0805, 1206, and 2512. Resistance values

range from 10 Ω–1 MΩ. Termination metals are platinum silver and platinum silver

with a 62/36/2 solder coating. The resistors

are suitable for amplifi ers and power supplies. Other features include 96% Al2O3 substrate material, tolerances up to ±1, and a standard passive-resistor element. International Manufacturing Services, Inc. (IMS), Portsmouth, R.I., www.ims-resistors.com

Dispensing Equipment

Dual-mode Spray HeadThe CAT 35 Integrated Liquid Delivery System (ILDS) dual-mode spray head

provides an alterna-tive to conventional air atomizing, fi lm coating, and dispens-ing technologies. The spray head consists of an ultrasonic trans-ducer with a titanium spray-forming head and integrated liq-uid and air applica-tors. The ultrasonic spray head has two modes: narrow mode has a 5-mm pat-tern width, and the wide mode features a 3–25-mm-pattern width. The head applies a thin, defect-free 0.5–5-mil-thick coat-ing, and works with urethanes; acrylics; water- and solvent-based coatings; and 100% solid, UV-curable conformal coat-ings. Ultrasonic Systems, Inc., Haverhill, Mass., www.ultraspray.com.

Screen Printing

In-line PrinterThe SP880avi is a 29" large-area in-line printer that incorporates two identical rov-ing cameras mounted on independent X/Y gantries — ensuring accurate, repeatable precision alignment. A paste-on-stencil

inspection feature lets users determine if there is adequate paste on the stencil prior to printing. The printer also features a user-interface that operates under a menu-driven, Windows XP application, and incorporates comprehensive, self-diagnos-tic capabilities, including production log-ging and automatic fault-report generation. Stored data can be accessed remotely using

a PC for on-the-fl y troubleshooting. An automatic stencil-loading facility also eases switching between 23–29" stencil frames. Available options include 2-D inspection, statistical process control (SPC), and a vac-uum-assisted wet/dry under-screen cleaner. Speedprint Technology Ltd., Dorset, Eng-land, www.speedprint-tech.com.

SOLDERING MATERIALS

Wave Solder FluxThe WF-9942 no-clean, no-residue wave solder fl ux works in mixed-technology and thru-hole applications. The fl ux features a wide process window and is said to reduce solder balling on all surface fi nishes. Its high thermal stability meets the high tem-perature requirements of lead-free wave soldering. The WF-9942 can be used with lead-free and tin/lead solder alloys. Indium Corporation of America, Clinton, N.Y., www.indium.com.

Test Equipment

Surface Roughness Tester Surftest SV-3000 is engineered around a column-moving system that reduces load-capacity limitations. Because of its 800- × 500- × 200-mm measuring enve-lope and long-stroke probe arm, the tester can accommodate sizable, heavy work pieces, and measure multiple cross sec-tions and waviness over a wide range. A standard I/O connection allows for the use of com-mon transfer and safety devices, as well as standard fi xtures. The tester can withstand vibration and reduce measurement changes of machine defl ection. Proprietary software provides analysis with 800-mm traverse capability, supporting automatic measurement and evaluation parameters. Mitutoyo America Corp., Aurora, Ill., www.mitutoyo.com. SMT




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This Advertiser Index is published as a service. The publisher does not assume any liability for errors or omissions.

3M ........................................................................................................ 21

AGC Chemicals Americas, Inc. ......................................................... 16

AMTECH .......................................................................................... C2

Asymtek, a Nordson Company .......................................................... 17

Balazs Analytical Services .................................................................. 15

Cookson Electronics Assembly Materials ........................................4-5

DEK ..................................................................................................... 35

Digi-Key Corporation .......................................................................... 2

Dow Corning Corp ...........................................................................C4

Electronic Controls Design, Inc. (ECD) .......................................... 14

ERC Co, Ltd. ...................................................................................... 31

ERSA NA ............................................................................................ 11

ITW Chemtronics .............................................................................. 29

Nix of America .............................................................................. 23, 34

P. Kay Metal, Inc. .............................................................................. C3

SMT Magazine .............................................................................. 28, 37

SIMCO ................................................................................................ 22

SMS Technologies, Inc. ..................................................................... 25

Tems - A Unit of ND Industries ........................................................ 26

Thermo Electron Corporation ............................................................ 1

ADVERTISER PAGE

POPP ING with News & Information

Magazine

WebsiteE-Newsletter

WebcastsWebcasts

Industry

Dire

cto

ry

Adve

rtisers In

dex

AOI / X-RAY INSPECTION

VISCOM, INC.3290 Green Pointe Pkwy.Ste. 400Norcross, GA 30092Phone: 678-966-9835Fax: 678-966-9828Corporate E-mail: [email protected] address: www.ViscomUSA.comViscom is the leader in Systems and Solutions for Automatic Optical (AOI) and X-Ray inspection worldwide. We offer a full range of dedicated AOI systems including; paste print inspection with 3D, post placement Inspection, post refl ow inspection and post wave solder inspection. We offer stand alone and In-Line X-Ray systems

MADELL TECHNOLOGY CORP7372 Walnut Ave. Suite VBuena Park, CA 90620Phone: 714-670-9023Fax: 714-670-1214Web address: www.madelltech.comQuality SMT Assembly Products at Unparalleled Prices. Madell Technology Corp. offers a complete line of SMT equipments for prototype, repair and production: hot air rework stations, BGA rework stations, stencil printers, table top and fl oor model refl ow ovens, automatic pick and place machines, paste dispensers, as well as through hole assembling equipment. Test and measurement, optical and biological equipments are also available at great prices.

SMT ASSEMBLY

For more information

on advertising in the SMT

Industry Directory section

contact: Rhonda Charron,

PennWell at (603) 891-9121

or e-mail:

[email protected]


MANUFACTURERS’ REPRESENTATIVE

RICH SALES COMPANY15547 N 77th St.Scottsdale, AZ 85260Phone: 888-860-7424Fax: 480-443-9256 Web address: www.richsales.com Established in 1978 Rich Sales covers the Greater Southwest, Mexico and Central America. Our Experienced Sales/Service organization encompasses 22 direct employees. Offi ces in Phoenix 480-443-9255; Dallas 972-529-0800; Austin 512-415-4038; El Paso 915-740-6201; Brownsville 956-793-0515; Guadalajara 011-523-33-6281351; Mexico City 011-523-33-157-5532; San Jose Costa Rica 011506-573-8634; Juarez 011-526-56-626-7997



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SM

T m

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etpla

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INLINE AQUEOUS CLEANING SYSTEM withstainless steel, high-temp/high-pressure

spray-in-air cleaning technology To l l - f ree : 800-545-0661

INLINE CLEANING SYSTEMwith Liquid Lock Advantage – reduce

operational costs by up to 75%!

A Powerful Team in Electronics Cleaning!

INLINE AQUEOUS CLEANING SYSTEM withstainless steel, high-temp/high-pressure

spray-in-air cleaning technology

INLINE CLEANING SYSTEMwith Liquid Lock Advantage – reduce

operational costs by up to 75%!

www.stoelting.com

Self Cleaning Squeegee SystemTransition Automation’s release of an innovative self-cleaning squeegee system offers end users relief to solder paste sticking to squeegees. This new squeegee holder has a built in wiper system, which cleans the squeegee after each print stroke. This new system retrofi ts into dual squeegee systems with no additional hook-ups. Please contact Transition Automation for more information. By fax: (978) 670-2300 or by email: [email protected]. Or visit us at the web: www.transitionautomation.com

www.transitionautomation.com

101 Billerica Ave., Bldg 5North Billerica, MA 01862

Ph: 978-670-5500Toll-Free: 800-648-3338

www.transitionautomation.com

CE Analytics Lead-Free Process Capability Validation ProgramThis comprehensive offering consists of:• CE Analytics evaluation and pro-

cess capability validation services to IPC and J-STD requirements.

• A Test Kit with lead-free solder paste, cored wire, stencil, laminates and pad fi nishes from Cookson Electronics

• A pick and place programming fi le (AegisCircuitCAMTM), lead-free components and boards available in multiple pad fi nishes from Practical Components.


For more information and ordering instructions, contact Cookson Electronics at 877-664-6232

»feeder4 free«Our SSF tape feeders are drop in compatible withSIPLACE® family placement machines; designedto enhance line operation and productivity.

We want you to try one for a month – FREE!Contact us: [email protected]

»feeder4 free«

www.hoverdavis.com

www.autosplice.com

ALPHA Vaculoy SACX0307Ride the lead-free wave to higher value with ALPHA Vaculoy SACX0307 wave solder alloy. Get all of the performance benefi ts of more expensive SAC305 at 30% less cost! SACX0307 offers:

• High process yield• High reliability• Easy transition to lead-free


Contact your Cookson representative to schedule a trial

in one of our global Lead-Free Demo Centers, or visit our website for

more information.

Adhesive and Sealant Custom Packaging Services

APS packages two-component reactive adhesives and sealants in A-PAK® flexible pouches, pre-mixed and frozen syringes and cartridges and various dual cartridge systems.Dual cartridge systems are availablewith mixing nozzles, dispensing gunsand other accessories.

For a Free Sample using your suppliedmaterial and for more information onother Custom Services, call ...1 (800) [email protected]

www.adhesivepackaging.com



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www.qualitek.com

www.qualitek.com www.qualitek.com

SM

T m

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Cla

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For more information on Classifi ed Advertising contact Rhonda Charron,

PennWell at 603-891-9102.

EQUIPMENT FOR SALE

THRU HOLE ASSEMBLY• Universal 6287 Axial Inserter• Universal 2596 Sequencer• Universal 6241C Inserter• Streckfuss Prep Equip

SURFACE MOUNT• Universal GSM II• AirVac DSR-22 Rework• Fuji QP Single Tray Unit• Fuji IP-III Placer• Zevatech 570L• Camelot XYFlex Dispencer

SOLDERING & CLEANING• Electrovert Econopak Plus• Heller 1700S Oven• Vitronics SMR800 R/L• Vitronic Isotherm Refl ow

K3 Equipment Co. LLC279 Front Street

Binghamton, NY 13905PH: (607) 773-2047; FX: (607) 773-0956

www.k3equipment.come-mail: [email protected]

9 5

Q: Why do Smart Sonic Stencil Cleaners outperform all others?A: Superior technology and 440-R® SMT Detergent. Good News! Award-winning 440-R® SMT Detergent is now available for use in any stencil cleaner! So, until that joyful day when you fi nally receive your own Smart Sonic Stencil Cleaner, 440-R® SMT Detergent will help you get the most out of your current machine or manual stencil cleaning process. Contact us for your sample today!

www.smtdetergent.com

E-mail: [email protected] Tel: 1-818-707-3110

Contact Rhonda Charron todayfor all the details!Tel: 603.891.9121

Email: [email protected]

The

SMT Marketplace

offers you a opportunity to stand out from your competitors!



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S M T P E R S P E C T I V E S


Over the last ten years, I have visited and evaluated customer’s manufactur-ing operations in all major electronic

manufacturing regions. I have experienced a great deal of variation in the sophistication of customer operations in the areas of pro-cess development, process optimization, and process control.

Some customers are sophisticated and dis-ciplined in the use of formal process develop-ment tools to identify, quantify, and optimize critical operating parameters of each indi-vidual process in the manufacturing oper-ation. These sophisticated operations have learned that there is no short cut to create a stable, high-performance manufacturing process. They have well-trained engineers doing sound engineering work. They spend a minor portion of their time fi re-fi ghting manufacturing problems; and understand that in a well-developed, optimized, and controlled process, manufacturing havoc is the exception, not the rule.

On the other end is the customer who does not use formal experimentation to under-stand and optimize a process. This customer will take information from suppliers, short trial runs, or other sources to establish pro-cess-operating parameters.

One frequent request from customers is, “Tell us the optimum operating parameters to run our process.” Unfortunately, no one can tell these companies what the optimum oper-ating parameters are for their particular pro-cess. Suppliers, industry studies, and other technical resources can provide guidelines to use when designing studies and experi-ments required to optimize a process. Each process is unique in its equipment, materi-als, environment, products, cycle time and quality requirements, operator and techni-cal support training and skills. Process opti-mization is not a one-size-fi ts-all proposi-tion. Only detailed experimental work on a company’s process will optimize that process. It is naive to think that anyone who is not involved in the process can identify the opti-mum process parameters without complet-ing the formal process development work.

When discussing the use of experimen-tation to develop and optimize a process, these companies often claim to be too busy to perform formal experimentation and statistical studies. The question is, “What are you too busy doing each day?” There is no doubt that many of these process engi-neers work very hard and are competent and conscientious. However, many have been observed doing little engineering work. For example, one customer required help implementing a lead-free process. On the fi rst day of the process, the manufacturing

engineering manager spent the majority of the day looking for a stencil. This is an example of an engineer who spent most of his day doing no engineering work because his operation had poor control of a vital tool.

At many other facilities, engineers spend much of their time adjusting process oper-ating parameters, looking for components, and reacting to a solder short or two. They primar-ily are fi xing the same problem every day because their processes are neither stable nor optimized.

Crisis is and always will be a part of elec-tronics manufacturing. However, when you have an unstable, under-performing pro-cess, all your time is devoted to crisis reso-lution, and little is devoted to sound engi-neering work to reduce cycle time, improve quality, reduce cost, and develop new man-ufacturing technologies. Support folks are

busy, but not effective in implementing meaningful process improvement.

To achieve optimum manufacturing per-formance, a signifi cant investment must be made in training the entire manufacturing operation in process development and opti-mization tools such as Design of Experi-ments (DOEs), statistical process control (SPC), problem solving, Design for Man-ufacturability (DFM), design for testability (DFT), and teaming.

The manufacturing technical support managers, along with well-trained opera-tors and dedicated management, must use the tools to design, optimize, and control manufacturing processes and solve specifi c manufacturing problems. The result will be a stable, optimized manufacturing process where crisis is the exception, not the rule.

One of the primary goals must be to reduce all non-value-added tasks such as inspection, test, repair, and rework. A nec-essary function such as test and inspection still does not add value to the product. Test

and inspection certainly have a role in the manufacture of electronics products, but pro-cess-engineering work should focus on reducing these steps to an absolute minimum. The way to do this is to cre-ate robust, in-control, repeat-able processes that produce acceptable results continually. The goal is to monitor a well-developed and optimized pro-cess using SPC, and not the

product using inspection.The entire manufacturing environment

must ask, “What am I too busy doing?” to ensure that what they are doing is what is required to provide signifi cant measurable process improvement. Being too busy and being effective is not the same thing. SMT

Joe Belmonte, project manager, ad-vanced process group, Speedline Tech-nologies, may be contacted via e-mail: [email protected].

What Are You Too Busy Doing?

“The entire manufacturing

environment must ask,

‘What am I too busy doing?’

to ensure that what they are

doing is what is required.”

By Joe Belmonte



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Introducing P. Kay MS2TM

molten solder surfactant.

At last—a product that actuallyeliminates dross.

Unlike conventional powders, oils, mechani-cal separators and even nitrogen blankets,MS2TM molten solder surfactant, a technologi-

cal breakthrough developed byP. Kay Metal, with U.S. and for-eign patents pending, doesn’tjust reduce or inhibit solderdross in wave soldering ma-chines—it actually eliminatesit.

Dross is formed when moltensolder comes into contact withoxygen. Dross consists of metaloxides plus otherwise good sol-der metal that is bound up withthe oxides and is thus unavailable for soldering. Thisbound-up metal makes up as much as 70% of the totalamount of dross, which in a typical wave soldermachine can amount to as much as 3 lbs. or more perhour.

MS2TM molten solder surfactant, which is available forboth leaded and lead-free processes, is a nontoxic, non-volatile, organic liquid that is poured onto the surfaceof the solder bath. About 200–300 ml is the averageamount for an initial charge; a smaller amount of freshproduct is usually added once or twice per shift.

MS2TM molten solder surfactant does not mix with themetal but forms a thin floating layer that covers theentire solder surface except the wave, which it does notdisturb. There are no fumes or odor and no residue isdeposited on boards or components.

When MS2TM molten solder surfactant is added to thesolder bath, it prevents dross from forming on the sur-face, and any dross generated by the exposed solderwave is immediately converted back into metal, so nodross accumulates.

Furthermore, as solder is pumped through the system,MS2TM molten solder surfactant keeps on removing

metal oxides, cleansing and purifying the bath. Theresult is lower surface tension, enhanced wetting andfewer solder-related defects.

As the layer of MS2TM moltensolder surfactant continues toconvert dross back to usablemetal, it will become thickerand more viscous, and can beeasily removed with a suppliedskimmer. The small volume ofspent material can then be inex-pensively shipped back to themanufacturer for recycling.

Imagine all the benefits of elim-inating dross from your soldering process. Not onlywill you have an immediate cost savings and anincrease in soldering quality, but your operators will nolonger be required to perform the dangerous task ofscooping up hot dross from the surface of the moltensolder.

To find out more, call us today at (800) 757-6533 or visitus at www.pkaymetal.com.

P. Kay Metal, Inc.2448 East 25th Street, Los Angeles, CA 90058

Tel: (323) 585-5058 Fax: (323) 585-1380www.pkaymetal.com

Immediate ROI

■ Reduces solder usage 40–75% based on production volume

■ Eliminates dross-related soldering defects and rework

■ Greatly reduces the cost of managing hazardous waste

ADVERTISEMENT

Please come Visit us at Nepcon Shanghai at the WKK Booth # 1F15



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Top performance takes teamwork.Packing ever more performance into smaller electronics components puts intense pressure on the

thermal interface. That’s why we’re constantly collaborating with customers to develop the latest thermal

management technologies. Our continuously expanding product offering includes both wet-dispensed

and fabricated options: adhesives, gels, encapsulants, greases, pads and films. These technologies,

combined with our alliances with equipment manufacturers and other suppliers, allow us to provide

total solutions. To find out more, contact the thermal management experts at [email protected].

© 2005 Dow Corning Corporation. All rights reserved. Dow Corning is a registered trademark of Dow Corning Corporation. A1042

team players

solution drivers

pacesetters

thermal specialists

profitability maximizers

problem solvers

results producers

speed-to-market enablers

process troubleshooters

marketplace matchmakers

need anticipators

customer collaborators

heat dissipaters

component enhancers

application advancers

front runners



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Documents

2006_Mar_SMT