Reducing Cost of Test of In-Circuit Test (ICT) for high mix, low volume PCBA manufacturing · 2012/3/29 · Test requirements of today‘s High Mix, Lower volume Production • Compact

Reducing Cost of Test of in-circuit test for

high mix, low volume PCBA manufacturing

Agilent Technologies

e-Seminar

Measurement Systems Division

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Presenter: Jonathan O’Connell B.Eng, C.Eng MIEE Service and Support Manager, Europe Measurement System Division (MSD)

Test requirements of today‘s High Mix, Lower volume Production

• Compact sized electronics products still rely on a functional test in production line test.

• High Speed Signal Device can prohibit the placement of test access

• SMT machines have better accuracy, less errors

• ICT has relatively High fixture cost and longer test development time compared to flying probe

• Traditional ICT has challenges to address requirements of High mix - low volume production.

BUT....Electrical Test is still needed

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What challenges do we have in improving test in low volume environment?

• Historical investments in different technologies means engineers have to „make do‟ with test

• No clear vision or commitment to test stages to address longer term

• Test strategy is done „transactionally‟ with each new business win/cycle.

• Test Economics – Test is still seen as an unwanted cost by some.

• End customer influences test strategy

BUT....Electrical Test is still needed

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What Strategy can you employ to lower costs and optimize coverage?

1. Rationalize Test stages - Standardize

• Consider Removal of obsolete test technology.

• Refresh/Upgrade platform using latest test techniques

• Test stage simplification and standardisation minimizes NRE expense/investment

2. Lower incremental Tooling costs

• Optimise or lower investment of your fixture/test interfaces

• Ensure any commitment to fixture also caters for design change

3. Economics of Coverage - Improve Effectiveness of Test

• Catch defects that current technology test stages can miss

• Focus on test coverage – not just Yield

4. Free up valuable Engineer resources

• Minimize engineering effort on „old‟ technology

• Recognise that additional engineering effort = money spent

5. Improve Cycle time

• Faster cycle times save cost, improves utilisation and speeds up NPI process

• means higher efficiency of test platform, provides greater test capacity

29th March 2012 4


29th March 2012 Measurement Systems Division

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Where Test Coverage Matters >Defect Detection Zone

Defect Prevention Zone

Consider how much you could save when you apply a new test strategy and increase test coverage ?

The Economics of Test – Where Coverage Matters

What information is needed during manufacturing?


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Actionable Information for Repair

Functional Test

Structural Test Inspection

What other information is needed ?


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Electrical test provides the Confidence to Ship Product!

Functional Test


Only a Combined Strategy Provides the Information Needed


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Functional Test


Both are Equally important in Manufacturing

Perspectives – Why Test?

ZERO defect really on exists in a dream .. If its NOT possible, then how to get a good product ?

Technology for defect detection/correction Imaging - inspection

In-circuit test functional test

defect generation: process defects

component defects functionality defects

Complementary Coverage Certainty Efficiency

SMT capability Human Training Process flow Supply chain

Good Product = Brand Image

At what cost ?

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Coverage “Imaging & Electrical Coverage are Different”

AXI 550 defects

ICT 62 defects

FT 13 def.

8 263

2

9

Insufficient

Excess

Void

Missing bypass caps

Shorts

Measured Value

Wrong Part

Programmable

Electrical Test Coverage can’t be met by imaging

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Certainty “Confidence or Assurance”

This is the challenge for the operator

There‟s another board behind this one

Do you have your answer?

This BGA costs $800

Is this expert interpretation?

What about a FALSE CALL?

What about an ESCAPES?

Subjectivity kills Certainty

Can You Find the Open??

Certainty

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Typical Structural Test Strategies for low volume

FUN TEST

ICT

ICT: In-Circuit Tester

FUN TEST

FPT

FPT: Flying Probe Tester MDA: Manufacturing Defect Analyzer

FUN TEST

MDA

Cost

& C

overa

ge

Two examples

Cost

& C

overa

ge

High Volume, Low Mix High complexity

Low Volume, High Mix Lower complexity

Very Low Volume, Very High Mix Not for manufacturing


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What is Flying Prober?


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Uses electro-mechanically controlled probes (flying robot arms) to access components.

Low coverage but very flexible, commonly used in prototyping and design houses.

Able to test extremely access-limited boards.

Detection of shorts and opens, as well as the verification of the presence and value verification of all analogue components.

Fixtureless

FUN TEST

FPT

FPT: Flying Probe Tester

Cost

& C

overa

ge

Flying Probers are a great fit for:

Small build NPI

NPI that won‟t convert to production

Ultra-low volume production

Extreme Access Limitations

When Flying Probe might stop making sense

Capacity Constraints

Inability to employ multi-panel testing for increased throughput.

High system utilisation, less flexibility

Long test time (in minutes) which is usually unacceptable for production.

Clogs up the rework loop

High Capital Cost

Do you account for engineering time?

What about Utilisation and running cost?


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Current Gen Flying Probe

MDA

Asset Cost 250k – 300K 30k-50k

Fixtures $0 $4k – 15k

Cost per board

@ $3/minute $15 - $180

$1 - $3

@50 bds per month yearly cost

$12,600 $1,200

@ $21/bd @ $2/bd

0.00

5,000.00

10,000.00

15,000.00

20,000.00

25,000.00

30,000.00

10 50 100 150 300 450 600 750 900 1250

Overall

Cost

Fixture Cost Comparison Exclusive of Coverage Costs

Flying Probers

MDA/ICT

Typical MDA’s …… use analog, limited power up Most Utilize Original TestJET invented by

HP/Agilent in 1993

*Or similar methods

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Why people use MDA?

A low cost, low coverage common board test facility in production lines providing „Just enough‟.

To detect/catch the defects which are made from manufacturing process:

Unexpected “Short”/”Open” between different pins/nodes.

Or the wrong, non-functioning, incorrectly installed and missing passive components (RLC).

Conventional MDA is a non-powered up board test.

Voltage and current measurements are made to individual components and the power is provided by the MDA instead.

Generally uses simpler, lower cost „Bed of Nails‟ fixtures that are cheaper compared to ICT

Very fast test time (in low seconds).


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MDA: Manufacturing Defect Analyzer

FUN TEST

MDA

Cost

& C

overa

ge

Personality Pins

Device under test

Probe

Test Coverage vs. Cost?

29th March 2012 Measurement Systems Division

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Consider that a few percentage points increase in test coverage (at every stage) can mean a huge saving in cost of repair at the next stage

Small difference in

test coverage

Huge difference

in cost savings

The ideal solution would be – Somewhere in the Middle….


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More Coverage vs. MDA

Less Fixture Cost vs. ICT

Less System Cost vs. ICT

Low Volume

High Volume

Scala

ble

Co

verag

e

MDA Low Coverage Tests

Low Fixture Cost

VTEP Coverage

Power UP Coverage

Boundary Scan Coverage

ICT

MDA

MDA+

Agilent Medalist i1000D MDA+ System


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Easy to use interface

Cost effective

Digital-capable MDA fixture

+True ICT functionalities

• Open/Shorts unpowered analog tests

• Powered analog tests

• VTEP v2.0 vectorless tests

• In-circuit Powered Digital Test

• On Board Serial Programming

• In-circuit Boundary Scan tests

• Interconnect Boundary Scan tests

• Agilent Cover Extend Technology

• Agilent Bead-Probe Technology

Vectorless - TestJET and VTEP

VTEP

Tests device’s pin to board connections

Effective for all kinds of packages.

Lead Frame based devices : SOIC, PLCC, QFP

Array based devices : BGA, uBGA, Flip Chip, etc

Leadframe

Bond wire

Die

VTEP/TestJet

Capacitor Sensor Plate

Stimulus

Probe

Bond wire

Solder

Balls

Die

VTEP

Capacitor Sensor Plate

Best Analog Coverage

0 8 ?

σ = 1.7

Cpk = ?

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MDA with

TestJET

ICs:

Tested Pins: 482

Testable: 1201

Coverage:41%

Connectors:

Tested Pins: 260

Testable: 450

Coverage:58%

I1000 with

VTEP(iVTEP)

ICs:

Tested Pins: 1168

Testable: 1201

Coverage:97%

Connectors:

Tested Pins: 445

Testable: 450

Coverage:98% DDR2 :Vcc/GND covered

sATA :Vcc/GND covered

Note: Testable pins =Total pins –Vcc-GND- No Access- same nail pins

VTEP

Testjet

σ = 0.3

σ = 1.7

Coverage 2.36x better

Best Analog Coverage TestJET vs VTEP

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Complete Bscan Test ( In-circuit Boundary Scan)

J2

J1

U1 U2

TDI1 TDI TAP TAP

TMS

TCK

TMS

Test Access

In-circuit Bscan Connect Tests Advance Interconnect Bscan Test

Complete Bscan Test

Flexible Digital Test

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Boundary Scan

device Connector or

other device

TDI TCK

TMS

TD0

VTEP

sensors

to ICT

tester …

Test Access

pins

Remove Test Access

Agilent Innovations Agilent’s Latest ICT Innovations + VTEP + Bscan

CET : NOW on ICs! Greater Throughput

Greater Coverage

Greater Usability

Greater Stability

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On-Board Programming

Easy to set up the process in

I1000 graphic user interface


29th March 2012 Page 24

i1000D digital capabilities Standalone Bscan Solution 8 pins / tap set

Programmer 10 pins / set

Digital IO 12 chs/ set

Digital IO SW Programming SW Bscan SW

Needs Buffer board for higher power driving capability

One Digital card, One Hardware and One Interface

=


Can offer the same functionality as these individual solutions

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Functional Test Integration - GPIB instrument


Switching Power Supplies

Backpla

ne

Fixture Top Plate

Test Fixture

Pin Cards

Contro

l O

utp

ut

Contro

ller IO

Card

USB-GPIB Adaptor

GPIB Device

DUT Power Supply

Oscilloscope - Vrms, Vpp, Freq, etc

Frequency Counter - RTC Calibration

Board Under Test

Board Under Test

GPIB Cable

USB Port

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User Friendly Interface

Analog interface_similar to MDA

Step by step program development

Digital debug GUI

Easy to Learn

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I1000 Fixture Overview

Cabled Press-Down fixture

Low cost fixture

Safety Sensor

Press-Down mechanism

Control/ Retest and Emergency Switch

•Long Wire fixture •Low Cost Fixture •Fast Fixture turnaround •Easy to debug •Compatible with MDA style fixtures

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Flexibility and Standardization Helps Reduce Cost of Test

SMT Simple FP/MDA

FCT #1 FCT #2 FCT #3

Open/Shorts Analog Test

Flash Programming

Voltage/ Current/ Frequency Measurement, Boundary Scan

Real Product Final Test

SMT i1000D

ICT FCT #3

Open/Shorts Analog Test

Flash Programming Voltage/Current/Frequency Measurement

Real Product Final Test

Flexible Powered Digital Test

Assembly

Assembly

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They don’t use ICT because:

– NPI projects, They use Flying Probe

Then, have Challenges in

– Flying Probe High Cost in both System and Maintenance

Results in

High Cost in NPI Test

Customer story: NPI projects

Requirements

1. Flexible Fixture Structure

2. Analog Test + Digital Test

3. Easy programming

DTS

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So we have also: i1000 Diagnostic Test Set

YES

Same Hardware Software

Same Innovations

DTS

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Flexible Fixture Structure to Save additional Fixture Cost in low volume production

Exchangeable Probe Plate

DTS

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Integration i1000DTS into system

I1000DTS Can form part of test system – or standalone

Example in Germany

DTS

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i1000D MDA+ Advantages

1. Best Analog Coverage by VTEP, and Bead Probe

• FP does not have VTEP to provide coverage to most of the IC.

• Agilent Bead Probe Technology expands the ICT life

2. Flexible Digital Test • Good Signal Quality and Per-Pin Digital Card.

– On-Board Programming, Boundary Scan Test

– Power up test , General Digital Test

• Functional Test Integration with GPIB instruments

3. Agilent Innovations by Cover Extend Technology, and more.

• CET provides the coverage that no other testers can get

This + provides much better test efficiency in High mix and low volume environment

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Conclusion and Key Points

Utilising MDA + in low volume, high mix can deliver:

One platform for test development

Lower Capital Costs

Provide Fast Cycle Time – no conflict for utilisation, more time for tuning test coverage

Accelerate NPI cycles – Test time is in seconds not minutes. Time to re-test , debug defect boards in NPI.

>30% Cheaper Fixture costs, although some compromise is needed on aesthetics

Capability to Rationalise , Standardize and combine test stages, improving efficiency

Reduction of Functional test cost

Is Flexible and future proof – can also be used if volumes increase


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Q&A

Documents

Reducing Cost of Test of In-Circuit Test (ICT) for high mix, low volume PCBA manufacturing · 2012/3/29 · Test requirements of today‘s High Mix, Lower volume Production • Compact