engineered materials - amtest · as imc (intermetallic) growth is less – good for ... preform –...

Cristian Tudor

Applications Engineer – Eastern Europe

Indium Corporation of Europe

Mobile: +40 723 171 396

E-mail: [email protected]

Web: www.indium.com

1 INDIUM CORPORATION CONFIDENTIAL

Amtest Seminar Training 2012

Engineered Materials

mailto:[email protected]

http://www.indium.com/


Agenda

• Preforms • Solder Wires • TacFluxes & Liquid Fluxes • Thermal Management – Heat Spring®


We offer over 400 Alloys

Largest Alloy Selection in the Industry


Considerations when using Engineered Solders

Alloy selection depends on:


• Temperature Constraints

– What is the max operating temp / reliability testing temp?

• End-Reliability Requirements

– Au/Sn is the strongest solder (highest tensile & shear strength)

– In-containing alloys are ductile – takes care of CTE mismatch

– great for heat transfer

– Bi-containing alloys are brittle and are not suitable for drop / vibration applications



• Metallization thickness - If Au thickness exceeds 15 microinches (381 microns)

– only Au & In-containing alloys recommended, as IMC (intermetallic) growth is less – good for solder joint

– Sn-based alloys if used will cause excess IMC & make the joint brittle & fail

• Step Soldering Operations?



Step Soldering

• Multiple Sequential Solder Operations

• Cannot re-melt existing solder joints

• Alloy Selection - T of 30-50C between melting

point of higher-temp alloy & max reflow temp of older lower-temp alloy

• Example – Au/Sn (280C); Sn/Ag (221C); In/Pb/Ag (154C)


Engineered Solder Products


Discs

Frames

Squares

Rectangles

Washers

Split Rings

Spheres

Arrays

Special

Preform Types


Solder Preforms vs Solder Paste

• Paste by its very definition has 50% flux by volume. Flux causes

– Outgassing / Voiding

– Potential cleaning issues with more flux residue

• Some aggressive metallizations need unique standalone fluxes that cannot be used as paste flux for rheology

– Eg. Soldering to Aluminium

• For non-planar substrates, placing a preform is easier than depositing paste

– Eg. Soldering in cavity setup


Preform Benefits:

The same solder joint is made over and over again. • Many copies in each Reflow Cycle

• Exact Amount of Solder Every Time

• No Scrap

• Flux-less Soldering

• Highly Reproducible

• Solder Hidden Areas

• Solve Non-Planar Problems

• Low to no voids


Preforms Manufacturing Process:

Material Flow

Ingot

Cast Extrusion Punch Packaging Preform



• Billet Cast

– Alloy purity determined

– Alloy lot-number assigned

– Form and size designed for extrusion press

• Extrusion

– Billet pressed into flat ribbon

– This is an intermediary process – final ribbon thickness is determined at rolling



Punch

• Die technology determines the X-Y dimensional tolerance

• Our knowledge of alloy properties is critical to our success in punch

– Die design

– Release mechanism

– Handling



Package, Label & Ship

• Many alloys and forms are soft so proper packaging is critical to avoid damage

• Packaging design is important to proper integration with customer processes (especially tape & reel)


Key Success Factors:

• Purity

• Dimensional Precision & Consistency

• Surface Characteristics

– Cleanliness

– Low Oxide

– Flatness

• Packaging


Preform Packaging:

• Bulk

• Stack pack

• Layer pack

• Tape and reel

• Waffle pack

• Custom packaging


Preform Packaging – Jar or Bulk Pack:


Preform Packaging – Tape & Reel:


Preform Packaging – Layer Pack:


Preform Packaging – Stack & Waffle Pack:


Preform Packaging – Tray Pack:


Integrated Preforms

• Provides exact solder volume

• Special shapes

• Made from Indium, Tin, Lead, Silver or alloy combinations of these.

• Thickness range from 0.005” (0.127 mm) to 0.018” (0.457 mm)

• Reduce process steps

• Standard Sheet Size is 5” (125 mm) x 9” (225 mm)


Preform Flux Coatings

• Controlled solder volume

• Controlled flux quantity 1-3% (No manual flux application)

• Lesser voids


Preform Fortification – Surface Mount Component

USB Device needs 150µ thick paste deposit, but other components need lesser paste

0402 Preform Fortification

Image Source : Motorola, Flensburg

http://www.dict.cc/englisch-deutsch/source.html


Preform Fortification – Surface Mount Component

Comparison

Without Preform

With Preform


Preform Fortification – Through Hole Component – Pin In Paste


Common Stencil Designs for Pin In Paste


Placing Preforms at Pin In Paste

• Preforms are packaged in Tape and Reel

• “0603” size

• Pick and Place equipment


Pin In Paste Results

• Preforms placed in Paste

• Observable Fillet

• 360º circumferential wetting

• IPC-B-610 Class 3

• Pin OD = .0235”


Preform – RF Shield Attach

Depending on the paste outline, preforms can be engineered to sit in the gaps or on the sides of the shield on top of solder paste

- 0.015” cubes

- Horse-shoe

- Longer preform strips


Fuse for Automotive Blower Motor – Special Shape “Horse Shoe”


Headlamp

Washer Preform Flux Coated


Mounting of Flex Circuits to Connector

Integrated Preforms (Connected Washers) or separate washers are used


Circular Connector Assembly

Integrated Preform


Pacemaker Assembly

Integrated Preform


Flux-Coated Preform- Fiber-Optic Application

Soldering a fiber optic wire to the housing using flux-coated preforms


Flux Coated Preform – Void Reduction for RF Power Amp

LDMOS Device with paste attach (gray color)

• Challenge: Void (>30%) & variability when using paste in convection reflow

• Goal: Voiding under PA < 20%

Voiding > 30%


Flux Coated Preform – Void Reduction for RF Power Amp

LDMOS Device with NC-9 flux-coated preform attach (blue color)

• Challenge: Void (>30%) & variability when using paste in convection reflow

• Goal: Voiding under PA < 20%

Voiding < 20%


Flux Coated Preform – QFN Void Reduction

• Flux-Coated preform

• Way lesser flux when compared to solder paste

Void reduced from 40% to under 20%


Key Success Factors:

• Purity

• Dimensional Precision & Consistency

• Surface Characteristics

– Cleanliness

– Low Oxide

– Flatness

• Packaging

Flux Cored Wires for PCBA Rework


Flux Cored Wires – Why Indium?

• Void-Free Flux Core

– It is a big deal

– Less than 3 complaints in 5 years as opposed to competition with 15 complaints / month

• Layer winding of wire for auto feed; prevents entanglement

• Wire for Selective Solder

• Wide alloy Range

– SAC, SnAg, SnPb, High-Pb, Sb-bearing (upto 8.5%), Bi-bearing (upto 14%), some In-bearing

• Low-cost NO-Ag option

• Flux designed for alloy as opposed to competition

• Large diameter range (0.25mm – 9.5mm dia)


Flux Cored Wires for PCBA Rework

Most Common for Pb-free & SnPb


Flux Cored Wires Low Ag & No Ag


Sn995 (Sn/0.7Cu + Cobalt dopant) wire

• NO Silver

• 1/3rd the cost of Ag alloys

• Better than Sn100C because Co in Sn995 is stabler than Ni in Sn100C and has a wider window w.r.t solder brightness

SAC105, SAC0307 wire

• Low Silver

• No problem

• No limitations

Wire Spool Sizes


Commonly Available Solder Wire Diameters and Spool Sizes

Most Common

Cored Wire – Cross Reference


Indium Alpha Kester Multicore AIM

CW807 Telecore 245 & 275 400 & X39 209AXT/ 209AX

CW301

Cleanline

7000 331 Hydro-X OAJ & WS482

CW201

Energized

Rosin 44 & 48

300 series & 500

series 210AX

Flux Core Stinks


- There is ALWAYS someone who doesn't like the smell of a new cored wire

- Often it is not that the smell is bad, BUT they prefer one smell over another because they are used to it and people don't like change.

- Worse does not always mean unacceptable.

- Different is not bad, it is just different.

Tacky Fluxes for PCBA Rework


Tacky Fluxes for PCBA Rework


Value Prop: Increased Reliability; accounts for operator depositing excess flux

Other Tacky Fluxes Specific to Alloy Composition


Value Prop: Unique Fluxes developed Specific to Alloy

Tac Flux Alloy Solder Form Comments

Tac 12 In-alloys (Ind#1E, 204…)

REMEMBER that these fluxes can be used for a preform or to complement a solder paste solution. Use to verify proof of concept with preform + flux, and then move to paste

No-Clean

Tac 57, 55, 21

Bi-alloys (Ind#282, 281…)

No-Clean

Tac 7 High-temp alloys (Au/Sn, High-Pb)

No-Clean

Tac 10 Low & High-temp alloys (SAC, Au/Sn, High-Pb)

No-Clean. Flux Residue is 1-3% (as opposed to regular flux with 35-45%)

TacFlux10 Ultra Low Residue Flux


Tac10 no-clean flux developed with ultra-low residue. Been in production for 10+ yrs

Issues w/ Regular Flux

• Voiding…

• Outgassing…

• Cosmetic finish affected….

• If not cleaned, could interfere with downstream operations like underfill, wirebonding…

Tac10 flux Regular Flux Comments

Solder Ball Test

Voiding– RF

Microwave appln w/ Au/Sn

----

Automotive Transducer Appln- Wirebonding with No cleaning

2.5% Void 10% Void

1-3% flux residue

35-45% flux residue

Packaging Tacky Fluxes


Value Prop: We can do any Syringe-Piston Pack

Packaging Tacky Fluxes


For hand dispensing of tacky fluxes, a thumb plunger can be used – this is not airless pack

For applications that use machine dispense, low-med-volume - Syringe with Wiper piston (to prevent flux bleed-out); Air-Free/Airless Pack – Best Effort (to

minimize bubbles in flux)

For applications that use high volumes with machine dispense, call us – we have proprietary techniques to

eliminate / minimize air bubbles (flux volume dependent)

Liquid Fluxes for PCBA Rework


Liquid Fluxes for PCBA Rework


Value Prop: Increased Reliability; accounts for operator depositing excess flux

Note: FP-500 & NC-771 (with a lower rosin content than FP-500) pass SIR unactivated

Other Liquid Fluxes


Value Prop: Unique fluxes for Unique Alloys &

Specific Metallizations

Research Kit – Liquid Fluxes


Heat Spring®


Material Description

– Made from Indium or Indium Tin as standard alloys

– Custom Alloys available

– We alter the surface so contact resistance is reduced

– We use high conductive metal 86w/mk

– We custom package for your application

– We standard pack in Tape and Reel

– We can recycle it and reclaim it

– We can offer you a credit on un-used material

– It’s a “green” TIM

TIMs - Heat Spring®


Bulk Thermal Resistance

0.00

0.02

0.04

0.06

0.08

0.10

0.12

0.14

0.16

0.18

0.20

0 20 40 60 80 100 120 140 160 180 200

Pressure (psi)

Th

erm

al R

esis

tan

ce (

cm

2-o

C/W

)

Thermal Grease #1 (2 mil)

Thermal Grease #2 (2 mil)

3 mil Indium Foil

3 mil HEAT-SPRING


Thermal Conductivity

• 100In; k= 87 W/m.K

• Grease; k= 3-10 W/m.K

Pumpout over time

• No pumpout with Solder-TIM

• Grease migrates from the center; poor thermals

Bakeout

• No bakeout with Solder-TIM

• Grease becomes powdery with bakeout ; poor thermals

Thermal Management - Solder-TIMs Vs Thermal Grease


Heat-Spring®

Reliability Testing


Time 0 Time 0

88 - 90

86 - 88

84 - 86

82 - 84

80 - 82

78 - 80

76 - 78

74 - 76

72 - 74

70 - 72

68 - 70

66 - 68

64 - 66

62 - 64

60 - 62

Time Zero for HSD vs. Grease showing Plot; Heat-Spring is running cooler at time zero


1561 Hr. @90C 1597 Hr. @90C

88 - 90

86 - 88

84 - 86

82 - 84

80 - 82

78 - 80

76 - 78

74 - 76

72 - 74

70 - 72

68 - 70

66 - 68

64 - 66

62 - 64

60 - 62

TTV Profile Comparison Bake 1500hrs


3108 Hr. @90C 3056 Hr. @90C

88 - 90

86 - 88

84 - 86

82 - 84

80 - 82

78 - 80

76 - 78

74 - 76

72 - 74

70 - 72

68 - 70

66 - 68

64 - 66

62 - 64

60 - 62

TTV Profile Comparison Bake 3000hrs


1000 Power-On Cycles 0-50 watts 3 minutes

power on, then 2 minutes power off Time 0

88 - 90

86 - 88

84 - 86

82 - 84

80 - 82

78 - 80

76 - 78

74 - 76

72 - 74

70 - 72

68 - 70

66 - 68

64 - 66

62 - 64

60 - 62

TTV Power Cycling Baseline Thermal Grease shows Pump-out


Thank You

engineered materials - amtest · as imc (intermetallic) growth is less – good for ... preform –...

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