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Lead Free Process GroupLead Free Process Group

Jasbir BathSolectron Corporation

Process Team Leader01-17-01

Connect with and Strengthen Your Supply ChainConnect with and Strengthen Your Supply Chain

AcknowledgementsAcknowledgements

• NEMI Lead Free Process Team

– Len Poch, Maurice Davis Universal Instruments

– Jeff Schake DEK USA Denis Barbini Vitronics-Soltec

– Oliver Bast Orbotech Steve Martell Sonoscan

– Mark Walz, Terry Leahy, Harold Hyman SRT/Genrad

– Jeremy Jessen Agilent

– Jana Coustineau Alcatel Frank Grano SCI

– Chuck Woychik IBM

– Al Gickler Johnson Manufacturing

– Ray Altieri Indium Corp.

– Dennis Bernier Kester Solder

– Rob Herber Alpha Metals

– Brian Bauer Heraeus

– Thilo Sack Celestica

Connect with and Strengthen Your Supply ChainConnect with and Strengthen Your Supply Chain01-17-01 2

AgendaAgenda

• Paste Evaluation (Solectron Milpitas)– Paste printability, X-ray inspection, Reflow

profile, Cross-sections, Pull/Shear tests

• NEMI Reliability Test board builds(Universal Instruments) - Printability,Placement, Reflow, Electrical Inspection

• X-ray inspection- Agilent Technologies

• Sonoscan Inspection

• AOI Inspection (Orbotech)

• BGA/ CSP rework (SRT/Genrad)

• Wave soldering evaluations (Vitronics-Soltec)


Paste Evaluation (Paste Evaluation (SolectronSolectron, Milpitas, CA), Milpitas, CA)

• Evaluate five Sn3.9Ag0.7Cu and five Sn37Pb solder pastes.Choose one SnPb and one SnAgCu paste for use on NEMIreliability test boards.

• Evaluation criteria:

• High Paste volume and good consistency of print on testboard on 16mil, 20mil QFP pads, 0402 chip pads, 1mm,1.27mm pitch BGA pads.

• Reflow with tin-lead coated components and lead-freecomponents placed on test board: visual inspection of jointsafter reflow (nitrogen atmosphere used in reflow oven). Testboard- OSP surface finish, 62mil FR4 board

• X-ray inspection: X-ray defect report for lead-free and tin-leadpaste soldered boards

• Cross-sections of selected components

• Pull tests/ Shear tests


Paste Evaluation(Paste Evaluation(SolectronSolectron Milpitas) Milpitas){-Max{-Max Vol Vol 16mil pads: 3840Cumils} 16mil pads: 3840Cumils}

16mil pitch pad Paste Volume and Standard Deviation of Volume

0

500

1000

1500

2000

2500

3000

3500

0 1 2 3 4 5Paste Number

Pas

te V

olu

me

(Cu

mils

)

AverageVolume SnPb

Stdev SnPb

AverageVolumeSnAgCuStdev SnAgCu


Paste Evaluation(Paste Evaluation(SolectronSolectron Milpitas) Milpitas)

50mil pitch BGA Paste Volume and Standard Deviation Paste Volume

0

1000

2000

3000

4000

5000

6000

0 1 2 3 4 5Paste Number

Pas

te V

olu

me

(Cu

mils

)

AverageSnAgCu

Stdev SnAgCu

Average SnPb

Stdev SnPb


Paste Evaluation(Paste Evaluation(SolectronSolectron Milpitas) Milpitas)SnAgCuSnAgCu Paste 4 (left): Paste 4 (left): SnPbPaste SnPbPaste 5 (right) 5 (right)



X-ray defect report for SnPb and SnAgCu solder pastes

0

200

400

600

800

1000

1200

1400

0 1 2 3 4 5

Paste Number

Def

ect

Nu

mb

er

Defect reportNo.SnPb

Defect reportNo.SnAgCu



Summary

Print scoresX-ray scoresSolderability Total Other commentsSnPb Paste 1 6 1 2 9SnPb Paste 2 0 2 3 5SnPb Paste 3 2 2 2 6SnPb Paste 4 1 2 3 6

SnPb Paste 5 4 3 3 10

SnAgCu Paste 1 3 0 1 4 Stencil Life issueSnAgCu Paste 2 1 0 1 2SnAgCu Paste 3 2 1 1 4

SnAgCu Paste 4 4 1 1 6SnAgCu Paste 5 1 1 1 3


Paste Evaluation(Paste Evaluation(SolectronSolectron Milpitas) Milpitas)NiPdNiPd QFP QFPSnPbSnPb Paste 5 (left): Paste 5 (left): SnAgCuPaste SnAgCuPaste 4 (right) 4 (right)


Paste Evaluation(SLR Milpitas)Pure Sn1206Paste Evaluation(SLR Milpitas)Pure Sn1206SnPbSnPb Paste 5 (left): Paste 5 (left): SnAgCuPaste SnAgCuPaste 4 (right) 4 (right)



Pull force for NiPd QFP leads before and after ageing (-40°C to 125°C, 1000

cycles)

0.00.51.01.52.02.53.0

Average

Pu

ll F

orc

e (l

bs)

Sn37Pb

SnAgCu

Sn37Pb(After ATC)

SnAgCu(After ATC)



Shear force (lbs) before and after ageing(-40°C to 125°C, 1000 cycles)

for pure tin coated 1206 chip

0.0

5.0

10.0

15.0

Average

Sh

ear

Fo

rce(

lbs) Sn37Pb

SnAgCu

Sn37Pb(AfterATC)SnAgCu(AfterATC)


NEMI Reliability Test Board Builds (UniversalNEMI Reliability Test Board Builds (UniversalInstruments SMT Lab, Binghamton, NY)Instruments SMT Lab, Binghamton, NY)

• DEK 265 Screen Printing Machine(plus SVS pasteinspection machine)

• Universal GSM placement machine

• Vitronics-Soltec reflow oven(10 zone) in Nitrogenatmosphere(<20ppm O2)

• 208CSP, 169CSP, 256PBGA, 256CerBGA,48TSSOP and 2512 resistor boards

• Lead-free Paste Component peak temperatures240-247°C(Time over 217°C: 61-90sec)

• Tin-lead Paste component peak temperatures 209-220°C(Time over 183°C: 83-88sec)

• 62 mil thick High Tg (170°C) FR4 board,Immersion Ag surface finish


X-ray Inspection (X-ray Inspection (AgilentAgilent, Loveland, CO), Loveland, CO)

• X-ray inspection of boards (Agilent 5DX)

• Initial observations:

• Lead-free paste with tin-lead components> voidingthan

• lead-free paste with lead-free components> voidingthan

• tin-lead paste with tin-lead components


AOI Inspection (AOI Inspection (OrbotechOrbotech, Santa Ana, CA), Santa Ana, CA)

• AOI inspection of lead-free and tin-lead TSSOP(NiPd/SnPb) and2512(Sn/Sn10Pb) resistor boards

• Evaluate and compare solder jointshape/geometry and wetting for:

• (1)Lead-free paste soldered withlead-free component

• (2) Lead-free paste soldered withtin-lead component

• (3) Tin-lead paste soldered with tin-lead component


GenradGenrad/SRT (/SRT (WestfordWestford,MA),MA)

• Rework NEMI 208CSP(0.8mm pitch) and256PBGA(1.27mm pitch) lead-free and tin-leadboards using SRT Summit 1100HR Plus machine

• Develop BGA/CSP rework profiles for lead-freepaste with lead-free and tin-lead components andcompare with profile for tin-lead paste with tin-lead component boards


BGA/CSP SRT/BGA/CSP SRT/GenradGenrad Rework Rework

• Additional control features were used to reworkthe SnAgCu solder alloy.

• “Positive air” feature was used to keep thetemperature of the top of the BGA to a moremodest temperature.

• Maximum BGA top surface temperature (purpleline) kept to 212°C

• while the solder joint was raised to 243°C andkept over melting point (217°C) for 74 seconds.


SonoscanSonoscan(Elk Grove Village, IL)(Elk Grove Village, IL)

• Inspect BGA/CSP and TSSOP components pre-assembly, post-assembly and post-thermalcycling for package delamination and otheranomalies

• 208CSP and 169CSP post-assembled tin-lead andlead-free boards inspected so far: No majoranomalies


Process TimelinesProcess Timelines

• NEMI Reliability test board builds: Complete:November 2000

• X-ray inspection: To be complete by Jan. 2001

• BGA rework evaluations: Complete by Jan/Feb.2001

• AOI inspection: Complete by Jan/Feb. 2001

• Sonoscan inspection:

• Pre-build: Completed Oct 2000

• Post-build: Complete by Jan/Feb 2001

• Post-thermal cycling: Complete by June 2001


Wave Solder Overview (Wave Solder Overview (VitronicsVitronics--SoltecSoltec,,Binghamton, NY)Binghamton, NY)

lead free process group - inemithor.inemi.org/webdownload/newsroom/presentations/... · genrad /srt...

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