Overview of flip chip research
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Overview of Flip Chip Research. Daniel Blass March 2002. Assembly. Lead-Free Assembly Flip Chip in Air Flux Jetting of Liquid No-Clean Fluxes Flip Chip on Flex Reflow Encapsulants Substrate Characterizations Information Needed For Yield Predictions Assembly Yield Software.

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Overview of flip chip research

Overview of Flip Chip Research

Daniel Blass

March 2002


Assembly

Assembly

  • Lead-Free Assembly

  • Flip Chip in Air

  • Flux Jetting of Liquid No-Clean Fluxes

  • Flip Chip on Flex

  • Reflow Encapsulants

  • Substrate Characterizations

    • Information Needed For Yield Predictions

  • Assembly Yield Software


Underfilling

Underfilling

  • Self-Filleting

  • Solder Extrusions & Trench Solder Mask Openings

  • Underfill Flow Modeling

  • Transfer Molding

    • No Void-Free Process Yet

  • Reflow Encapsulant Codification

    • Process Cook-Book / Guide

  • Underfilling Codification


Reliability

Reliability

  • Moisture and Aging

    • Fillet Cracking Experiments

    • Crack Growth Experiments and Modeling

  • Lead-Free Reliability

    • Pad Finish

    • Reflow Attach Profile

    • Additional Reflows/JEDEC Level 3 Test

  • Transfer Molded Flip Chips

    • Results Comparable to a Capillary Flow Underfill


High temp jedec level 3 testing

High Temp JEDEC Level 3 Testing

  • Moisture/Reflow Sensitivity Classification for Nonhermetic Solid State Surface Mount Devices

  • Component Qualification Test

  • Moisture Load Parts and Reflow 3 Times

  • Most Lead-Free Alloys Require Much Hotter Reflow Temperatures

  • Qualify to Higher Reflow Temperatures


Lead free assembly

Lead-Free Assembly

  • LF-2 (Sn95.5Ag3.5Cu1.0) from K&S Flip Chip

    • Liquidus of Approx. 217°C

  • Previous Process Recommendations

    • Dip in 2.0 mil of Kester TSF-6522 Flux

    • Nitrogen Reflow Atmosphere (50 ppm O2)

    • Peak Reflow Temperature of 238°C to 245°C

    • 50 to 70 Seconds Above 217°C

    • Soldering to Ni/Au or Cu-OSP Pads (Entek Plus)

  • This Process, However, Has Not Given Consistent Defect-Free Assembly

    • Incomplete Wetting of Pad, Poor Self-Centering

    • Only One Electrical Open (on Cu-OSP Pads)


Cross sections of lf 2 defects

Cross-Sections of LF-2 Defects


X ray images of lf 2 defects

X-Ray Images of LF-2 Defects


Better soldering to ni au pads

Better Soldering to Ni/Au Pads

  • 250+ Chips On Each Pad Finish


Most lf 2 chips attached to ni au pads had no defects

Most LF-2 Chips Attached to Ni/Au Pads Had No Defects

  • 250+ Chips On Each Pad Finish


Sample sizes with each process

Sample Sizes with Each Process

Largest Sample Sizes Built With Profile B or Profile G & 2 mil Kester TSF-6522


Overview of flip chip research

Average Defects Per Chip on Each Ni/Au Board Built With Profile B or G & 2 mil of Kester TSF-6522 Flux


Overview of flip chip research

Average Defects Per Chip on Each Cu-OSP Board Built With Profile B or G & 2 mil of Kester TSF-6522 Flux


No clear profile preference for ni au pads

No Clear Profile Preference for Ni/Au Pads


No clear profile preference for cu osp pads

No Clear Profile Preference for Cu-OSP Pads


Large variation within each process

Large Variation Within Each Process

  • Limits Ability to Compare Processes that Have Smaller Sample Sizes

  • Would Have to Build Many More Die To Decide Whether a Reflow Profile Was Better

  • All Processes Gave Soldering Defects


Thicker flux often gave more defects

Thicker Flux Often Gave More Defects

  • Real Effect or Just Small Sample Sizes?

  • Good that 1.5 mil of Flux Is Not Worse


Future direction of lead free assembly

Future Direction of Lead-Free Assembly

  • New “Lead-Free” Fluxes

    • Heraeus TF69

      • Not Suitable for Drum Fluxer: Large Solid Particles

    • Indium TAC 23

    • Kester R903

    • Have Not Eliminated Soldering Defects

  • Flux-Jetting of Liquid No-Clean Fluxes


Future direction of lead free assembly1

Future Direction of Lead-Free Assembly

  • Alternative Finishes

    • Cu / Omikrontm Immersion White Tin

    • Cu / AlphaLEVELtm Organo-Metallic Immersion Silver

    • Electroless Ni / Immersion Silver (ENIS)

      • Would Likely to Have Same Reliability Issues as Electroless Ni / Immersion Au (ENIG)

  • Reflow Profile Optimization

  • Other Alloys?

    • Limited Soldering Trials with Sn/Ag/Bi

    • Interest?


Lead free reflow profiles

Lead-Free Reflow Profiles

  • Profile Optimization

  • Lower Soak Temp

  • Shorter Soak or No Soak

  • Sharper Spike to Reflow

  • Longer Time at Peak


Lead free reliability

Lead-Free Reliability

  • Pad Finish

    • Better Reliability on Cu-OSP Pads

  • Thermal History

    • Reflow Profile Used to Attach Chips

    • Additional Reflows

      • Changes to Fatigue Resistance

      • Damage to Underfilled System

  • No Failures Attributed to the Soldering Defects

    • Solder Fatigue Cracks Are Found Near Chip

    • Defect Level Does Not Correlate to Failure Time


Poor correlation of defect levels to failure time

Poor Correlation of Defect Levels to Failure Time

• Dexter FP4549, Cu-OSP Pads, Profiles B & G


Llts results for chips attached to cu osp pads

Namics U8437-3 Underfill

LLTS Results for Chips Attached to Cu-OSP Pads


Llts results for chips attached to ni au pads

Namics U8437-3 Underfill

LLTS Results for Chips Attached to Ni/Au Pads


Better reliability for chips attached to cu osp pads

Namics U8437-3 Underfill

Better Reliability for Chips Attached to Cu-OSP Pads


Solder joint is different on ni au pads

Solder Joint is Different on Ni/Au Pads

  • Copper Substitutes Into Ni-Sn Intermetallic Layers

    • Depletes Copper From Solder

  • Sn/Ag Joint on Ni/Au Pads

  • Sn/Ag/Cu Joint on Cu-OSP Pads

EDX Map Showing Copper Segregation to Intermetallic Layers

Cu

Nickel-VanadiumChip UBM

NickelSubstrate Pad

Sn/Ag


Intermetallic growth

Intermetallic Growth

  • Parts Supplied By Member of the Consortium

    • 10 mil Pitch Perimeter Bumped Chip

      • Ni UBM Layer

    • Substrates with Ni/Au and Cu-OSP Pads

    • Chips Bumped With 3 Different Alloys

      • Sn95.5Ag4.0Cu0.5 different from LF-2 (Sn95.5Ag3.5Cu1.0)

      • Eutectic Sn/Pb

      • Sn95.5Ag3.5Bi1.0 (limited supply)

  • High Temperature Storage Tests

  • Thermal Cycling


Aging of sn 95 5 ag 4 0 cu 0 5 flip chips

Aging of Sn95.5Ag4.0Cu0.5 Flip Chips

  • Aging at 125°C

    • 500 hours

    • 1000 hours

  • Little Intermetallic Growth For Chips Attached to Ni/Au Pads

  • Continued Intermetallic Growth For Chips Attached to Cu-OSP Pads

  • Both Results Consistent With Previous Investigations for LF-2 (Sn95.5Ag3.5Cu1.0)

  • Aging at 150°C

    • 500 hours

    • 1000 hours


125 c aging of sn 95 5 ag 4 0 cu 0 5 flip chip joints soldered cu osp

125°C Aging of Sn95.5Ag4.0Cu0.5 Flip Chip Joints Soldered Cu-OSP

As Reflowed

1000 hrs at 125°C


150 c aging of sn 95 5 ag 4 0 cu 0 5 flip chip joints soldered cu osp

150°C Aging of Sn95.5Ag4.0Cu0.5 Flip Chip Joints Soldered Cu-OSP

500 hrs at 150°C

1000 hrs at 150°C


Continuing intermetallic investigation

Continuing Intermetallic Investigation

  • Determination of Intermetallic Phase Compositions

    • At Interfaces

    • In Bulk Solder

  • Amount of the Various Phases

  • Understand the Growth Kinetics

    • Thermodynamics

    • Diffusion Mechanisms

  • Similar Analysis After 500 and 1000 cycles of Air to Air Thermal Cycling

    • -40°C to 125°C

    • -40°C to 150°C


Lf 2 reliability after high temperature jedec level 3 test

LF-2 Reliability after High Temperature JEDEC Level 3 Test

  • Performed High Temperature JEDEC Level 3 Testing

    • Peak Temperatures of 244°C and 260°C

  • Both Namics U8437-3 and Dexter FP4549 Underfills Failed at 260°C

    • Small Areas of Underfill Delamination at Chip-Underfill Interface

    • No Popcorning

  • Decreased LLTS Performance

    • Change in Solder Properties or Underfill Damage?


Multiple reflow experiment

Multiple Reflow Experiment

  • Namics U8437-3 Underfill

  • Not a JEDEC Level Test

    • No Moisture Exposure

  • Profile 250 Used for All Reflows (250°C Peak)


Llts results for ni au pads after extra reflows

LLTS Results for Ni/Au Padsafter Extra Reflows


Llts results for cu osp pads after extra reflows

LLTS Results for Cu-OSP Padsafter Extra Reflows


Extra reflows after underfilling caused more delamination in llts

Extra Reflows After Underfilling Caused More Delamination in LLTS


Lead free summary

Lead-Free Summary

  • Better Soldering to Ni/Au Pads than to Cu-OSP

  • No Electrical Opens Caused By Soldering Defects

    • Either in Assembly or Subsequent Reliability Testing

    • Yield Concerns for Pad Designs that Give Less Collapse

    • Concerned About Poor Self-Centering on Cu-OSP Pads

  • Better Reliability with Cu-OSP Pads than with Ni/Au Pads

    • Ni/Au Pads Are More Sensitive to Thermal History

  • Need Better Soldering to Cu-OSP Pads or to an Alternative Non-Nickel Pad Finish


Flex circuit design

Copper Coated With Shikoku GLICOAT OSP

Photoimageable Coverlay

Adhesives

Base Polyimide

Metal Stiffener

Flex Circuit Design

One Big Coverlay Opening


Flip chip on flex

Flip Chip on Flex

  • Substrate Design

    • Work Around Poor Coverlay Tolerances

    • Large Window Opening to Define Pads

  • Handling / Fixturing

    • Want To Keep Die Area Flat During Placement and Reflow

    • Limit Handling Until Underfill Is Cured

    • Stiffeners Can Help But Not Lightweight Solution

    • Stiffeners Can Act As a Spring

      • Not a Problem with Dip Fluxing

      • Defects with Reflow Encapsulants Because Some Chips Shifted When Next Chip Was Placed


Flip chip on flex1

Flip Chip on Flex

  • Soldering to the Large Solderable Pads

    • Often Hear Concerns About “Too Much” Collapse

    • Shikoku GLICOAT OSP on Copper Pads

      • Supposed to Limit Solder Wetting to Pad Area

  • Used Typical Flip Chip Assembly Process

    • 1.5 to 2.2 mil of No-Clean Paste Flux

    • SMT Style Profile With Nitrogen (<50ppm O2)

    • Good Collapse But Gap Still Large Enough to Underfill

  • Underfilling

    • Could Not Use Chip Edges for Fiducials

    • Underfill Sometimes Pooled On Coverlay Without Wetting Edge of Chip


Solder wetting with 1 5 mil of kester tsf 6502 flux

Solder Wetting with 1.5 mil of Kester TSF-6502 Flux

Copper

Solder


Solder wetting with 2 2 mil of kester tsf 6502 flux

Solder Wetting with 2.2 mil of Kester TSF-6502 Flux

  • All Copper Covered With Solder


Reflow encapsulants no flow underfills

Reflow Encapsulants / No-Flow Underfills

  • Less Forgiving Approach This Year

    • Will Not Slow Down Placement Machine

      • Should Be as Fast as Dip Fluxing in Placement Machine

    • Wide Solder Reflow Process Window Needed For SMT Integration

      • Hotter Soak and Peak Temperatures

  • Standard Placement and Soldering Trials

    • Designed to Quickly Weed Out Poor Performers Without Assembling Many Chips

    • Determine Whether a Material Is Worth More Effort

    • More Work Would Be Needed to Define Process


Reflow encapsulants

Reflow Encapsulants

  • Alpha Fry Technologies NUF 2071E

  • Dexter Hysol FF2000

  • Dexter Hysol FF2200

  • Emerson & Cuming 11129-152C (for BGAs & CSPs)

  • Emerson & Cuming JS11156-24 (for BGAs & CSPs)

  • Emerson & Cuming XNF1500

  • Kester SE-CURE 9101

  • Kester LX2-2-13 (SE-CURE 9125)

  • Loctite X237115

  • 3M UF3400

  • Sumitomo CRP-4700A

  • Sumitomo CRP-4750A (30wt% silica filler)


Battery of 10 profiles for reflow encapsulant soldering evaluation

Battery of 10 Profiles for Reflow Encapsulant Soldering Evaluation


Battery of 10 profiles for reflow encapsulant soldering evaluation1

Battery of 10 Profiles for Reflow Encapsulant Soldering Evaluation

  • Soak Stage Temperature

  • Length of Soak Stage

  • Peak Reflow Temperature


Reflow encapsulant evaluation

Reflow Encapsulant Evaluation

  • Dexter Hysol FF2000

    • No Post-Cure Step

    • No-Soak, Volcano Profile Recommended

  • Dexter Hysol FF2200

    • 5-10 minute Cure at 165°C

    • May Be Sensitive to Higher Soaks

    • Good in Previous Reliability Testing

  • Loctite X237115

    • No Post-Cure Step

    • Gelled in Hotter, Longer Soaks

    • No Reliability Data


Reflow encapsulant evaluation cont d

Reflow Encapsulant Evaluation (Cont’d)

  • Kester SE-CURE 9101

    • 30 minute Cure at 160°C

    • Wide Soldering Window

    • Good Reliability in Reliability Testing

    • Needs Most Substrate Bakeout

  • Kester LX2-2-13 (SE-CURE 9125)

    • No Post-Cure Step

    • Soldered OK in All Tested Profiles

    • No Reliability Data


Reflow encapsulants not recommended

Reflow Encapsulants Not Recommended

  • Alpha Fry Technologies NUF 2071E

    • Voiding Issues (May Need Longer Bakeout)

    • Weird Reflow Profile

  • Emerson & Cuming XNF1500

    • No Post-Cure

    • Soldered Great

    • Reliability Not as Good as Other Materials

  • 3M UF3400

    • Viscous, Needed Slow Placement Times

  • Sumitomo CRP-4700A

    • Did Not Cure After Hours at 150°C

  • Sumitomo CRP-4750A (30wt% silica filler)

    • Filler Sometimes Prevented Solder Joint Formation


Prebake studies

Prebake Studies

  • Normal Prebake Recommendation For Capillary Underfilling is 2 Hours at 125°C

    • Conservative, Shorter Prebakes Are Possible

  • Reflow Encapsulants See Higher Temperatures

    • Drives More Moisture Out of Board

  • Needed Prebake Depends on Reflow Encapsulant

  • Depends on Substrate Design

    • Copper Planes Under Chip?

  • Time Between Bakeout and Assembly

    • Accumulation of Ambient Moisture

    • Moisture Deep in Board Can Diffuse to Outer Layers


Little prebake needed for emerson cuming xnf1500

Little Prebake Needed for Emerson & Cuming XNF1500

No Prebake

15 Minutes at 125C

  • 1 Reflow with Peak 220°C Was Also Sufficient

62 mil Thick FR-4


Much longer prebake at 125 c needed for kester 9101

Much Longer Prebake at 125°CNeeded for Kester 9101

No Prebake

15 Min

30 Min

45 Min

1 Hour

2 hour

62 mil Thick FR-4


Multiple reflows needed to dry board for kester 9101

2 Reflows

4 Reflows

3 Reflows

5 Reflows

1 Reflow

Multiple Reflows Needed to Dry Board for Kester 9101

NoVoids

31 mil Thick FR-4


Bga csp assembly for an automotive application

BGA / CSP Assembly for an Automotive Application

  • 27mm 388 I/O Motorola PBGA

  • 8mm 64 I/O TI Star

  • 4 Encapsulants Considered

    • Dexter FF2200

    • Emerson & Cuming 11129-152C

    • Emerson & Cuming JS11156-24

    • Kester 9101


Bga csp assembly concerns

BGA / CSP Assembly Concerns

  • Bakeout of Both Substrate and Components

  • Dispense Pattern For Large Components

    • Maker Sure All Balls Are Fluxed

    • Minimize Placement Voids, If Possible

    • Takes A Long Time to Dispense

  • Different Thermal Profiles Experienced By Large and Small Components on Same Board

    • Wide Reflow Process Window to Prevent Underfill Gelling for Small Parts or Corner Balls of Big Parts

    • 14°C Difference in Peak Temp for These Components

  • High Placement Force and/or Hold Time


Bga csp assembly concerns cont d

BGA / CSP Assembly Concerns (Cont’d)

  • Underfill Wetting Away From Component

    • Cover Other Components

  • Large Volume of Liquid Reflow Encapsulant Must Be Squeezed Out From Under Component During Soldering

    • Could Hold Up Component

  • Component Warpage

    • No Extra Solder Volume From Paste Printing

    • Will Not Work For All Components

  • Will All Balls Touch Pad & Solder?

  • Generally Not Reworkable


Placement bubbles in center pbga array

Placement Bubbles in Center PBGA Array

  • All Materials Had Similar Placement Bubbles

  • E & C 11129-152C HadFewer Voids After Reflow

    • Some Bubbles Dissolved During Reflow

    • A Nice Quality to Have in a Reflow Encapsulant

    • Also Depends on Bubble Size

  • Dexter FF2200

  • Placed on a Glass Slide


Placement voids deformed solder joints during reflow

Placement Voids Deformed Solder Joints During Reflow

Voids


Some pbga assembly defects because of component warpage encapsulant gelling

Some PBGA Assembly Defects Because of Component Warpage & Encapsulant Gelling

Corner Balls Sometimes Did Not Solder


Reflow encapsulant build for reliability testing

Reflow Encapsulant Build For Reliability Testing

  • Not a Good Process For All BGA and CSP Packages


Stencil printing reflow encapsulants

Stencil Printing Reflow Encapsulants

  • Small Flip Chip in Package

  • Printed Deposits For a Strip of Components

    • High Throughput Compared to Dispensing

    • Obviously Not Compatible With Solder Paste Printing

    • Removes Fluxing From Placement Machine

  • Promising Trials With Existing Materials

    • Materials Not Optimized For Printing


Larger flip chip in package

Larger Flip Chip in Package

  • 8 mm Area Array Chip with 700+ Bumps

  • Voids Everywhere

  • Changing Dispense Patterns Does NotHelp

  • Reflowed on Glass Slide

  • Kester 9101


Kester 9101 voids shrank during post cure

Kester 9101 Voids Shrank During Post-Cure

After Cure

After Reflow


Jedec level 3 testing of reflow encapsulant

JEDEC Level 3 Testing of Reflow Encapsulant

  • Dexter FF2200

  • Kester 9101

  • Kester LX2-2-13 (SE-CURE 9125)

  • Tested 30 Chips With Each Material

  • All Passed JEDEC Level 3 With 240°C


Reflow encapsulant summary

Reflow Encapsulant Summary

  • More Standardized Assembly Evaluation

  • Prebake Requirements Vary

  • Can Make Bubbles and Voids Dissolve

    • Important For Area Array Bump Layouts

  • Stencil Printing Could Be an Option

  • Looking at Several Flip Chip in Package Possibilities

    • Probably Needs Overmolded for Reliability

  • Lead-Free?


Self filleting underfills

Self-Filleting Underfills

  • Can Increase Underfill Dispenser Productivity

  • Need Fillet For Good Reliability

  • Want to Minimize Fillet Variation

    • Prevent Fillet Cracking and Early Failure


Self filleting productivity

Self-Filleting: Productivity

  • Underfill Flow Times Are Not an Issue if There Are Enough Chips in the Underfill Dispenser

    • Dispenser Can Always Be Dispensing

    • Will Not Sit Idle Waiting on Underfill Flow

  • Dispensing Time

    • More Dispense Passes Per Chip Means Fewer Chips Underfilled

  • Self-Filleting Underfills

    • Eliminates Dispensing Close-up Pass to Form Fillets


Self filleting factors that affect underfill wetting and flow

Self-Filleting: Factors That Affect Underfill Wetting and Flow

  • Underfill Selection

  • Flux Selection

  • Chip Passivation/Coating

  • Solder Mask and/or Laminate

  • Chip Size

  • Any Contamination

  • Self-Filleting Will Be Sensitive to Changes in These Factors (Planned or Accidental)


Self filleting experiment

Nitride Passivated Sn/Pb bumped PB8 Chips

Taiyo PSR-4000 Solder Mask

0.5 to 1.0 mil Gap Between Chip and Solder Mask

4 No-Clean Paste Fluxes

Heraeus TF38

Indium FC-NC-LT-C

Kester 9603

Kester TSF-6502

11 Underfills

Dexter CNB845-27

Dexter FP4549

Emerson & Cuming E-1172

Honeywell JM8802

Kester 9203

Namics U8434-6

Namics U8437-3

Namics U8443

Shin-Etsu X43-5600XSWF-1

Sumitomo CRP-4152S

Sumitomo CRP-4300A

Self-Filleting Experiment


Fillet thickness measurements for different types of self filleting

Fillet Thickness Measurements For Different Types of Self-Filleting

  • Kester 9603 Flux


Examples of different self filleting

Examples of Different Self-Filleting

Poor Self-FilletingNo Exit Fillet

Self-Fillets But Thinner Exit Fillet

Good Self-Filleting

Namics U8437-3

& Heraeus TF38 Flux

Shin-Etsu X43-5600XWF-1

&Kester 9603 Flux

Namics U8434-6

& Indium FC-NC-LT-C Flux


Self filleting for the different underfill flux combinations

Fluxes

Underfills

Heraeus TF38

Indium FC-NC-LT-C

Kester 9603

Kester TSF-6502

Dexter CNB868-38

SCATTER

SCATTER

SCATTER

SCATTER

Dexter Hysol FP4549

GOOD

GOOD

SCATTER

GOOD

Emerson & Cuming 1172

SCATTER

SCATTER

SCATTER

SCATTER

Honeywell JM8802

POOR

POOR

POOR

POOR

Kester 9203

POOR

POOR

POOR

POOR

Namics U8434-6

SCATTER

SCATTER

SCATTER

POOR

Namics U8437-3

POOR

POOR

POOR

POOR

Namics U8443

GOOD

GOOD

GOOD

SCATTER

Shin-Etsu X43-5600XWF-1

GOOD

GOOD

GOOD

GOOD

Sumitomo 4300A

GOOD

GOOD

SCATTER

GOOD

Sumitomo 4152S

GOOD

GOOD

SCATTER

GOOD

Self-Filleting for the Different Underfill-Flux Combinations

  • Nitride Passivated Chip

  • Taiyo PSR4000 Mask


Trench solder mask openings solder extrusions

Trench Solder Mask Openings & Solder Extrusions

  • Can Be a Convenient Way to Define Flip Chip Pads

  • Trenches Increase Chance of Forming Underfill Voids Near Solder Joints

  • Voids Provide a Path For Solder to Migrate During Thermal Excursions (Cycling or Reflow)

  • Solder Extrusion & Bridging (Electrical Short)

    • Bridging Only for Finer Pitches

    • Unlikely Above 10 mil Pitch


Voids most likely when underfill flows parallel to the trench opening

Voids Most Likely When Underfill Flows Parallel to the Trench Opening

Underfill Flow Direction


X ray image of a solder bridge after jedec level 3 test

X-Ray Image of a Solder Bridge After JEDEC Level 3 Test


How do you prevent voids in trench openings

How Do You Prevent Voids in Trench Openings?

  • Pick the Right Underfill-Flux Combination

    • No Perfect Combination

  • Can the Cure Process Be Adjusted to Make Small Voids Dissolve?

    • Slower Ramp?

  • Use Individual Mask Openings for Each Pad


Use of trench for fine pitches less than 10 mil

Use of Trench For Fine Pitches(Less Than 10 mil)

  • If Underfilled Chip Will Be Reflowed

    • Flip in Package or on Board (DCA)

    • Use Individual Solder Mask Openings

      • Photodefined or Laser Ablated

      • Will Cost More

  • High Temperature Service and Cycling Requirements

    • Probably Should Use Individual Mask Openings

  • Mild Service Requirements

    • Extrusions May Form Too Slowly to Be a Concern


High temp jedec level 3 testing1

High Temp JEDEC Level 3 Testing

  • Moisture/Reflow Sensitivity Classification for Nonhermetic Solid State Surface Mount Devices

    • Component Qualification Test

    • Moisture Load Parts and Reflow 3 Times

      • Peak Temperature Depends on Component Type & Size

      • JEDEC Level 3: 8 Days of 30°C/60%R.H.

    • Failures: Popcorning, Delamination, Cracking, Electrical Failure, Solder Bridging

      • For Unseen Damage or Weakening, Additional Testing Recommended

  • Most Lead-Free Alloys Require Much Hotter Reflow Temperatures


High temp jedec level 3 testing2

High Temp JEDEC Level 3 Testing

  • Current Standard (IPC/JEDEC J-STD-020A)

    • Peak Temperature of 220°C / 235°C

    • BGAs classified at 220°C Peak Reflow Temperature

  • Draft of Future Standard (IPC/JEDEC J-STD-020B)

    • Sn/Pb Eutectic to be Classified at 225°C / 240°C

    • “Lead Free” to be Classified at 245°C / 250°C

  • Our Experiments Used 220°C, 240°C, and 260°C

    • Sn/Pb and Sn/Ag/Cu Bumped Chips

    • Only Chips With Nitride Passivation


Jedec level 3 with very fine gap

Sn/Pb PB8 Chips

High Tg FR-4 Board

62 mil Thick

4 Metal Layers

Taiyo PSR-4000

0.5 to 1.0 mil Gap Between Chip and Solder Mask

4 No-Clean Paste Fluxes

Heraeus TF38

Indium FC-NC-LT-C

Kester 9603

Kester TSF-6502

12 Underfills

Dexter CNB845-27

Dexter FP4549

Emerson & Cuming E-1172

Emerson & Cuming E-1252

Honeywell JM8802

Kester 9203

Namics U8434-6

Namics U8437-3

Namics U8443

Shin-Etsu X43-5600XSWF-1

Sumitomo CRP-4152S

Sumitomo CRP-4300A

JEDEC Level 3 With Very Fine Gap


Small gap hurt jedec level 3 results

No-Clean Paste Fluxes

Underfills

Heraeus TF38

Indium FC-NC-LT-C

Kester 9603

Kester TSF-6502

Dexter CNB 868-38

1/8 Failed

4/8 Failed

4/8 Failed

6/8 Failed

Dexter FP4549

Passed

Passed

1/8 Failed

1/8 Failed

Emerson & Cuming E-1172

Passed

Passed

5/8 Failed

1/8 Failed

Emerson & Cuming E-1252

Passed

Passed

5/8 Failed

3/8 Failed , 2 PC

Honeywell JM8802

Passed

Passed

Passed

Passed

Kester 9203

Passed

Passed

Passed

Passed

Namics U8434-6

7/8 Failed

1/8 Failed

Passed

Passed

Namics U8437-3

3/8 Failed

5/8 Failed

Passed

3/8 Failed

Namics U8443

1/8 Failed

5/8 Failed

2/8 Failed

1/8 Failed

Shin-Etsu X-43-5600XWF-1

1/8 Failed

1/8 Failed

Passed

Passed

Sumitomo 4152S

1/8 Failed

3/8 Failed

Passed

Passed

Sumitomo 4300A

Passed

Passed

Passed

Passed

PC = Popcorn Failure

Small Gap Hurt JEDEC Level 3 Results

  • Half of the Underfill-Flux Combinations Passed at 220°C


Small gap hurt jedec level 3 results1

Small Gap Hurt JEDEC Level 3 Results

No-Clean Paste Fluxes

  • Only 4 Underfill-Flux Combinations Passed at 240°C

Underfills

Heraeus TF38

Indium FC-NC-LT-C

Kester 9603

Kester TSF-6502

Dexter CNB 868-38

16/16 Failed , 11 PC

16/16 Failed , 8 PC

16/16 Failed , 7 PC

16/16 Failed , 12 PC

Dexter FP4549

4/16 Failed , 1 PC

3/16 Failed

2/16 Failed

2/16 Failed

Emerson & Cuming E-1172

16/16 Failed

16/16 Failed

16/16 Failed , 1 PC

16/16 Failed

Emerson & Cuming E-1252

16/16 Failed , 8 PC

14/16 Failed , 10 PC

Passed

Honeywell JM8802

11/16 Failed

1/16 Failed

1/12 Failed

Kester 9203

16/16 Failed , 16 PC

16/16 Failed , 12 PC

11/13 Failed, 5 PC

14/16 Failed , 6 PC

Namics U8434-6

16/16 Failed , 7 PC

16/16 Failed , 3 PC

10/16 Failed, 7 PC

10/16 Failed , 8 PC

Namics U8437-3

16/16 Failed

16/16 Failed

16/16 Failed

16/16 Failed

Namics U8443

16/16 Failed , 14 PC

16/16 Failed, 12 PC

14/16 Failed, 6 PC

15/16 Failed , 4 PC

Shin-Etsu X-43-5600XWF-1

15/16 Failed , 7 PC

16/16 Failed , 1 PC

16/16 Failed

14/16 Failed

Sumitomo 4152S

13/16 Failed

3/16 Failed

8/16 Failed

4/16 Failed

Passed

Passed

Passed

Sumitomo 4300A

1/16 Failed

PC = Popcorn Failures


Jedec level 3 240 c with 2 mil gap

Non-Snap Cure Underfills

Dexter CNB 845-27/FP4546

Dexter CNB 861-05

Dexter CNB 868-38

Dexter CNB 881-21

Dexter CNB 886-8

Dexter CNB 887-37

Dexter FP4549

Namics U8434-6

Namics U8437-2

Namics U8437-3

Shin-Etsu X-43-5600XSPW-1

Shin-Etsu X-43-5603QHT

Sumitomo CRP-4152G

Sumitomo CRP-4300A

Snap Cure Underfills

Dexter CNB 865-46

Dexter FP4531

Emerson & Cuming E-1172

Emerson & Cuming E-1216

Emerson & Cuming E-1252

Emerson & Cuming 11899-41

Kester 9208

Loctite RDP0960

Loctite 3593 (unfilled)

3 No-Clean Paste Fluxes

Heraeus TF38

Indium FC-NC-LT-C

Kester TSF-6502

JEDEC Level 3 / 240°C With 2 Mil Gap


Jedec level 3 240 c with 2 mil gap1

Indium

Kester

Underfill

Heraeus TF38

NC- FC-LT-C

TSF6502

Dexter CNB 865-46

5/5 Failed + 1PC

5/5 Failed + 3PC

5/5 Failed

Dexter FP4531

5/5 Failed

5/5 Failed + 4PC

5/5 Failed

Emerson & Cuming 11891-41

6/8 Failed

7/8 Failed

4/8 Failed

Emerson & Cuming E-1172

Passed

5/5 Failed

2/5 Failed

Emerson & Cuming E-1216

Passed

4/5 Failed

Passed

Emerson & Cuming E-1252

5/5 Failed

5/5 Failed, 2 PC

4/5 Failed

Kester 9208

4/5 Failed

5/5 Failed

Loctite 3593

Passed

Passed

Passed

Loctite RDP 0960

Passed

Passed

Passed

JEDEC Level 3 / 240°C With 2 Mil Gap

  • Few Snap Cure Underfills Will Pass at 240°C


Jedec level 3 260 c with 2 mil gap

JEDEC Level 3 / 260°C With 2 Mil Gap

  • Some Snap Cure Underfills Can Also Pass at 260°C


Jedec level 3 240 c with 2 mil gap2

JEDEC Level 3 / 240°C With 2 Mil Gap

  • Most Non-Snap Cure Underfills Passed at 240°C

  • No Popcorn Failures


Jedec level 3 240 c with 2 mil gap3

JEDEC Level 3 / 240°C With 2 Mil Gap

  • Tested a Subset of the Underfills With More Fluxes


Jedec level 3 260 c with 2 mil gap1

JEDEC Level 3 / 260°C With 2 Mil Gap

  • Five Underfills Passed at 260°C With All 3 Fluxes


High temperature jedec summary

High Temperature JEDEC Summary

  • Better Results Than Expected

    • A Number of Materials Capable of 260°C Peak

  • Small Gaps Hurt Performance

  • Snap Cure Underfills Were More Likely to Fail and to Popcorn

  • Have Not Tested Subsequent Reliability of the Parts That Pass JEDEC

    • Expect Reduction As Seen With Lead-Free Parts


Codification projects

Codification Projects

  • Defect Prediction Programs

    • Placement Yield

      • Now Has Illustrated Help Files

    • Assembly Yield

      • Now Includes Solder Bridging Defects

  • Step-By-Step Guides

    • Emphasis on Creating a Database About Your Materials & Equipment So That Less Effort Required to Develop Product Specific Processes

    • Underfill Process

    • Reflow Encapsulant Assembly

      • New This Year


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