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

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


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

  • 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

  • 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

  • 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


X-Ray Images of LF-2 Defects


Better Soldering to Ni/Au Pads

  • 250+ Chips On Each Pad Finish


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

  • 250+ Chips On Each Pad Finish


Sample Sizes with Each Process

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


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


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 Cu-OSP Pads


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

  • Real Effect or Just Small Sample Sizes?

  • Good that 1.5 mil of Flux Is Not Worse


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 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

  • Profile Optimization

  • Lower Soak Temp

  • Shorter Soak or No Soak

  • Sharper Spike to Reflow

  • Longer Time at Peak


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

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


Namics U8437-3 Underfill

LLTS Results for Chips Attached to Cu-OSP Pads


Namics U8437-3 Underfill

LLTS Results for Chips Attached to Ni/Au Pads


Namics U8437-3 Underfill

Better Reliability for Chips Attached to Cu-OSP 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

  • 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 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 Sn95.5Ag4.0Cu0.5 Flip Chip Joints Soldered Cu-OSP

As Reflowed

1000 hrs at 125°C


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

  • 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

  • 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

  • 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 Padsafter Extra Reflows


LLTS Results for Cu-OSP Padsafter Extra Reflows


Extra Reflows After Underfilling Caused More Delamination in LLTS


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


Copper Coated With Shikoku GLICOAT OSP

Photoimageable Coverlay

Adhesives

Base Polyimide

Metal Stiffener

Flex Circuit Design

One Big Coverlay Opening


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 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

Copper

Solder


Solder Wetting with 2.2 mil of Kester TSF-6502 Flux

  • All Copper Covered With Solder


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

  • 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

  • Soak Stage Temperature

  • Length of Soak Stage

  • Peak Reflow Temperature


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)

  • 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

  • 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

  • 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

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°CNeeded for Kester 9101

No Prebake

15 Min

30 Min

45 Min

1 Hour

2 hour

62 mil Thick FR-4


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

  • 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

  • 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)

  • 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

  • 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

Voids


Some PBGA Assembly Defects Because of Component Warpage & Encapsulant Gelling

Corner Balls Sometimes Did Not Solder


Reflow Encapsulant Build For Reliability Testing

  • Not a Good Process For All BGA and CSP Packages


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

  • 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

After Cure

After Reflow


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

  • 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

  • Can Increase Underfill Dispenser Productivity

  • Need Fillet For Good Reliability

  • Want to Minimize Fillet Variation

    • Prevent Fillet Cracking and Early Failure


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

  • 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)


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

  • Kester 9603 Flux


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


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

  • 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

Underfill Flow Direction


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


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)

  • 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 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 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


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


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 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


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


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

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


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 Gap

  • Tested a Subset of the Underfills With More Fluxes


JEDEC Level 3 / 260°C With 2 Mil Gap

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


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

  • 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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