PCB LAMINATES - royalcircuits.com · laminates are a balance between signal performance and...

PCB LAMINATESPresented by Royal Circuit Solutionsand Insulectro

Royal Circuit Solutions

Quick Turn PCB Specialist:Over the last 20 years, Royal Circuits has become the leader in quick-turn, high-tech PCB manufacturing – with no minimum order quantity and single day turn-times. Using the latest technology and cutting-edge equipment, we are building the Factory of the Future with the capability to manufacture any kind of circuit board – from simple 2-layers to complex HDI boards - fast.

Royal Circuit Solutions

RigidHollister, CA Quick turn, turn key, FR4, Polyimide, HSD and RF. Heavy copper (> 3.0 oz). Proto to production.

Flex and Rigid FlexSanta Fe Springs, CAQuick turn, specialty applications

Offer a wide range of PCB materials from premier suppliers. Isola, DuPont, LCOA, CAC, Pacothane, Oak Mitsui, JX Nippon

Maintain the critical mass required to provide better access to products and technical support for the electronics industry.

Provide Local Inventory

Customers access material in hours

On-site technical support

ACT! Accomplish Change Together Support fabricators with their customers

Provide support for proper material selection

Insulectro: Electronic Materials

Who needs a PCB?

The Grundig: It has no PCB

Going back to the 1940’s

Materials for many technology Applications

Design Success• PCB’s are no longer simple replacements for wires.

• They are an integral part of the design.

• You don’t need to be material science experts.

• Many of the new materials bring technology and/or performance advantages.

• We are here to help.

PCB Rigid Laminates

Each component plays a role in providing the right properties for the design.

Common Thin Core Construction

½ oz copper foil

Core dielectricTypically 3.0 to 8.0 mils

1 oz copper foil

Signal Circuitry

Plane

What Royal Circuits does with the material

Blank layer , copper is on both sides with laminate (dielectric) in the middle.

After etching the copper in a pattern, the laminate in the middle is revealed. The copper is coated with a brown bond treatment.

SideView

Copper clad thin cores are stacked to make a complex web of circuits.

6 Layer PCB 72 layer PCB

Copper plating brings all of the layers together

Copper clad thin cores are stacked to make a complex web of circuits.

Because of these…. Sometimes we

need to do this

Some Important PROPERTIES

GLASSTRANSITION

TEMPERATURE

DECOMPOSITIONTEMPERATURE

COEFFICIENTOF THERMALEXPANSION

DIELECTRICCONSTANT

DISSIPATIONFACTOR

Dk DfTdTg

Why and how we choose a PCB laminate

Impedance (Controlled Impedance)– Dk (dielectric constant)– Thickness

Signal Loss (loss tangent/Df dissipation factor)– Df of resin and glass

Skew Control– Spread glass, Dk matching

Embedded Passives– Buried capacitance, buried resistors

Cost and Availability

Cost vs performance to

meet your requirements

Dk – Dielectric Constant

- Used for obtaining proper impedance, signal properties

- Often spec’d over a range because exact value will vary even within the same family depending on dielectric thickness and glass to resin ratio.

- Also dependent on temperature, moisture and frequency used in the design.

PCB Dielectric Constant

- While the materials have a Dk rating, PCB fabrication requires the combination of “building blocks” such as prepreg and thin cores.

- Prepreg type, resin content and circuit design can have Dk effects.

- Your fabricator uses design software combined with use history to create effective stack-ups.

So Many Materials

More on this later

Rigid Laminate: Glass Fabric

Standard MS GlassE-Glass Low Dk E-Glass Low Dk

Very Common

Excellent resin fill

Good for heavy copper

No good for skew at higher speeds

Same as E-glass, but with lower dielectric

constant.

Low signal skew

Good for Diff pairs

Very good thickness control

Same as MS E-glass, but with lower

dielectric constant.

Fiberglass Standard Weave

SPECSAbout 2.0 mils

Great for fill of heavy coppers.

Least dimensionally stable.

106

SPECSAbout 2.5 milsGood for fill.

1080

SPECS3.0 to 3.5 mils

Some fill propertiesGood stability

2113

SPECS7.0 to 8.0 mils

Good for building thickness.

Best for dimensional stability.

7628

Fiberglass Spread Weave

SPECSAbout 2.0 mils

Great for thickness controlGood for laser drilling

Low signal skewNot good for filling

1067

SPECSAbout 3.0 Mils

Great for thickness controlGood for laser drilling

Low signal skewNot good for filling

1086

SPECS3.0 to 4.0 milsAlso low skew

Great for thickness control

3313

SPECS5.0 to 6.0 milsAlso low skew

Great for thickness control

1652

24

Differential Pairs and Skew

PrePreg Skewed from glass weave 22.5°

38” wide prepreg, 81.9 linear inches for 4- 22.5° 18x24 sheets21.6 square feet to yield 12 square feet. (55.5% yield)

Helps with skew, but

very bad for cost.Material

Web

Your PCB Fabricator

PCB Building BlocksYour fabricator will make recommendations for the best stack-up based on the design.

For example: An HSD design with 2 oz power planes will need open weave prepreg between these layers, not spread glass.Spread glass does not fill as well, and it’s also not needed between planes anyway (no need to reduce signal skew).

Other Properties

Dissipation FactorA material property that characterizes signal loss. Resin, glass and copper foil all play a roll in this.

UL RatingUL-796 covers PWBUL-94 covers flame ratingUL 94-V0 is most commonOther: V1, V2, HB, etc.

Moisture AbsorptionUsually as a weight percent.Impacts assembly, Dk and Df

Time to DelaminationTest to determine thermal robustness. Sample are heated and kept hot until failure.

Df

Some materials from the same supplier are in the same UL family

How Digital Designers Look at Materials

•Eye Patterns– Tells how well a signal is

transmitted through a link.– Random bits are driven and

averaged.– Variation in the x axis is

related to timing variations (jitter)

– Variation in the y axis is related to amplitude variations (noise)

4” Stripline FR4

1 Gbps 3 Gbps 5Gps

8 Gbps 10 Gbps 12.5 Gbps

Using a lower loss material will open the “eye” at higher speeds.

Combination of the following;Material loss (Df)Conductor (Copper Trace)

Trace roughnessTrace width and thicknessTrace Length

Total loss = Dielectric loss + Conductor Loss

• Signal integrity is often the most important need in a

design.

• As speed increases, loss becomes more important.

The same circuit at higher speeds will have higher loss.

Overview: Resin Types

Type Properties ApplicationsMultifunctional

EpoxyThermoset

Easy to processStandard PCB

Most economicalPolyimide Thermoset

Very High TgHigh operating temp

Mil/AeroPPO/PPE

BlendsThermoset

Low loss (Df) and low DkProcessing can be easy to hard

High Speed Digital RF

PTFE ThermoplasticVery low Dk

Very high lamination temp

High Speed DigitalRF

FR4 Material

FR = Flame Retardant- A wide variety from low Tg (not suitable for lead-free) to high Tg

like FR408HR (190°C)

- All epoxy based, but be specific on type

- Lead free specify Tg >170°C and Td (decomp) >325°C

- Some types stocked in house

- Heavy (thick) coppers available

Unfilled vs. Filled resin system

33

High Speed Material- Resin chemistry and glass type (if used) provide higher signal

performance over FR4

- Dissipation Factor & Dielectric constant are important considerations. Dk is <4.0 and Df is <0.010

- Low profile copper (HVLP) provides better results (Lower Loss)

- Get stack-up from VENDOR for future revisions

- Insulectro I-Tera MT40, FR408HR and I-Speed

- Nelco 4000-13

- Rogers RO4003

High Frequency Material- RF designs

- Lowest Df and consistent Dk – Low Dk glass

- Often hybrid boards with one piece of high speed laminate and rest FR4

- Ceramic Rogers RO4000

- Teflon based Rogers RO3000 and Taconic

- I-Tera MT40

- Astra MT77

I-Tera MT40 and Astra MT77 laminate like and are highly compatible with FR4

Electrodeposited Copper Foil Production

Conductor (Cu Foil)As frequency / bit rate increases, the copper foil topography should be considered.

When more of the signal travels on the surface of the conductor, the rougher the surface, the higher the loss.

Copper Roughness Impact

• When the roughness of the copper surface becomes close to the wavelength of the signal, the loss increases.

• This begins to be a big factor at frequencies of 10 GHz and higher.

• The benefits of a low loss laminate can be undone with rough copper.

Standard VLP2

Copper Foil Types

Low Profile copper Reduces Signal lossSEM’s of copper foil surfaces from

standard to VLP2

High performance laminates are a balance

between signal performance and

thermomechanical performance.

Yes, these are at the same magnification.

Typically, HVLP or VLP2 coppers come at a cost

premium

Polyimide Material

- Very high glass transition temperature(>240°C) and low CTE

- High temperature / High reliability applications

- Able to do lots of repeated soldering

- Brittle

- Low outgassing

- Hygroscopic

Important Questions• Signal loss: High speed digital (>2 GHz) , RF or both?

• Density

• Impedance control: Dk, overall thickness and layer count?

• High operating temperature?

• High Power: Heavy copper (>2.0 oz.)?

• High Voltage?

• Special mechanical requirements?• Flexibility, weight?

• Availability? Cost?

Other PCB Technology• Embedded Capacitors

• Embedded Resistors

• Screenable Components

• Z-Axis Paste interconnets

mSAP• Modified Semi-Additive Process

• Uses Ultra-Thin Foil

• Photo resist and copper plating forms circuit traces

• Below are 15/15 and 10/10 L/S plated to about 15 microns thick

Flex materials Overview

Kapton®

•Kapton was first produced in the 60’s

•Once used in space suits as a micrometeoriod barrier

•Still extensively Used in space

•LF adhesive was first produced around 1976

•Basis of many flexible PCB’s

•More applications in Rigid PCB

Apollo/Skylab A7L suit

Pyralux®

•Aerospace

•Outer space

•Medical

•Exploration

Mars Rover

Flex PCB Types

Flexible Circuit Materials

Polyimide film is the “backbone” of flexible PCB’s– Usually Kapton Film, different from rigid

polyimide– Very good high temperature performance– Very good electrical performance– Cost goes up dramatically with thickness

above 2.0 mils – Can be used in rigid PCB’s for thin layers; i.e.

buried capacitance– Layers are joined with glass free acrylic or

epoxy adhesives

Most flexible copper clads will use RA (rolled annealed) copper foil.

Flex Materials

Questions?Email Lisa@royalcircuits.com, allison@royalcircuits.com orCHunrath@Insulectro.com with additional questions

Thank you!