Creep Properties of Lead-free Solder Joints · 2005-09-22 · Creep Properties of Lead-free Solder...

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Creep Properties of Lead-free Solder Joints Materials Science Division Lawrence Berkeley National Laboratory Department of Materials Science and Engineering University of California at Berkeley UCLA Workshop on Pb-Free Solder September 4-5, 2002 Department of Materials Science and Engineering, University of California, Berkeley and Materials Science Division, Lawrence Berkeley National Laboratory Intel Corporation, Santa Clara, California 1 2 J.W. Morris, Jr 1 , H.G. Song 1 and F. Hua 2

Transcript of Creep Properties of Lead-free Solder Joints · 2005-09-22 · Creep Properties of Lead-free Solder...

Page 1: Creep Properties of Lead-free Solder Joints · 2005-09-22 · Creep Properties of Lead-free Solder Joints Materials Science Division Lawrence Berkeley National Laboratory Department

Materials Science DivisionLawrence Berkeley National Laboratory

Department of Materials Science and EngineeringUniversity of California at Berkeley

Creep Properties of Lead-free Solder Joints

Materials Science DivisionLawrence Berkeley National Laboratory

Department of Materials Science and EngineeringUniversity of California at Berkeley

UCLA Workshop on Pb-Free Solder September 4-5, 2002

Department of Materials Science and Engineering, University of California, Berkeley and Materials Science Division, Lawrence Berkeley National Laboratory

Intel Corporation, Santa Clara, California

1

2

J.W. Morris, Jr1, H.G. Song1 and F. Hua2

Page 2: Creep Properties of Lead-free Solder Joints · 2005-09-22 · Creep Properties of Lead-free Solder Joints Materials Science Division Lawrence Berkeley National Laboratory Department

Materials Science DivisionLawrence Berkeley National Laboratory

Department of Materials Science and EngineeringUniversity of California at Berkeley

Motivation

• High homologous temperature during thermal fatigue means that creep is a major deformation mode.

• Creep behavior of Lead(Pb)-free solder joints in shear must be known to use them reliably in microelectronic applications.

Page 3: Creep Properties of Lead-free Solder Joints · 2005-09-22 · Creep Properties of Lead-free Solder Joints Materials Science Division Lawrence Berkeley National Laboratory Department

Materials Science DivisionLawrence Berkeley National Laboratory

Department of Materials Science and EngineeringUniversity of California at Berkeley

Pb-Free Solders of Interest in This Work

Solder System M.P.(?C) Constituent phases T/Tmat R.T.

Sn-0.7Cu 227 β-Sn, Cu6Sn5 0.596

Sn-3.5Ag 221 β-Sn, Ag3Sn 0.603

Sn-10In-3.1Ag 204 β-Sn, Ag2In, γ-InSn 0.625

Sn-3Ag-0.5Cu 218 β-Sn, Ag3Sn, Cu6Sn5 0.607

Page 4: Creep Properties of Lead-free Solder Joints · 2005-09-22 · Creep Properties of Lead-free Solder Joints Materials Science Division Lawrence Berkeley National Laboratory Department

Materials Science DivisionLawrence Berkeley National Laboratory

Department of Materials Science and EngineeringUniversity of California at Berkeley

Experimental Procedure

• Solder alloy manufacturing– Alloyed by vacuum arc melting – Rolled to make foil after homoginization– Punched to get the constant volume of solder

• Test specimen manufacturing– Manufactured solder masked Cu coupons with 9 pads – Assembled to single-shear specimens with bare Cu and electroless

Ni/immersion Au plated coupons – Reflow and annealing

• Creep tests– Performed at 60, 95, 130?C under constant load conditions

Page 5: Creep Properties of Lead-free Solder Joints · 2005-09-22 · Creep Properties of Lead-free Solder Joints Materials Science Division Lawrence Berkeley National Laboratory Department

Materials Science DivisionLawrence Berkeley National Laboratory

Department of Materials Science and EngineeringUniversity of California at Berkeley

Reflow Profile (at N2 atmosphere)

Reflow peak temperature of 235oC for SnAg, SnInAg, SnAgCu and 245oC for SnCu

5 10 15 20 25Time(min)

0

Tem

pera

ture

(?C

)

50

250

200

150

100

300

Cooling (2.7oC/sec)

Flux Activation

Reflow

Preheat

245oC

235oC

Followed by aging at 160oC for 4 hours.

Page 6: Creep Properties of Lead-free Solder Joints · 2005-09-22 · Creep Properties of Lead-free Solder Joints Materials Science Division Lawrence Berkeley National Laboratory Department

Materials Science DivisionLawrence Berkeley National Laboratory

Department of Materials Science and EngineeringUniversity of California at Berkeley

Geometry of Single-Shear Specimen

Cu or Ni/Au metallization

Alignment hole

Oxygen-free Cu plate

66m

m

2.23mm

1.21mm

3.18mm

Solder Resist Coating

13mm

t

F

F

(160µm)

One coupon has Cu pads

One coupon haselectroless Ni / immersion Au pads.

Page 7: Creep Properties of Lead-free Solder Joints · 2005-09-22 · Creep Properties of Lead-free Solder Joints Materials Science Division Lawrence Berkeley National Laboratory Department

Materials Science DivisionLawrence Berkeley National Laboratory

Department of Materials Science and EngineeringUniversity of California at Berkeley

Creep Test Apparatus

LVDTLVDT

micrometermicrometer

specimenspecimen

gripgrip

specimenspecimen

oil bathoil bath

loadload

heating coilheating coil

micrometermicrometerLVDTLVDT

thermocouplthermocouplee

Page 8: Creep Properties of Lead-free Solder Joints · 2005-09-22 · Creep Properties of Lead-free Solder Joints Materials Science Division Lawrence Berkeley National Laboratory Department

Materials Science DivisionLawrence Berkeley National Laboratory

Department of Materials Science and EngineeringUniversity of California at Berkeley

Typical Creep Curves of Solder Joints

0.0 2.0x104 4.0x104 6.0x104 8.0x104

0

20

40

60

80

100

Shea

r stra

in(%

)

Time(sec)

0 5 10 15 20 Time(hrs)

Sn-0.7Cu at 130oC

3.63MPa4.53MPa5.44MPa

2.72MPa1.81MPa

Page 9: Creep Properties of Lead-free Solder Joints · 2005-09-22 · Creep Properties of Lead-free Solder Joints Materials Science Division Lawrence Berkeley National Laboratory Department

Materials Science DivisionLawrence Berkeley National Laboratory

Department of Materials Science and EngineeringUniversity of California at Berkeley

1 2 3 4 5 6 7 8 910 20 30 4010-8

10-7

10-6

10-5

10-4

10-3

10-2

10-1

100

1(all)n-value

St

rain

rate

Shear Stress(MPa)

n=3.5

n=4.0

n=4.1

95?C130?C

60?C

n=7.0 n=7.7

n=9.4

SnCu: Shear Stress vs. Shear Strain rate

Page 10: Creep Properties of Lead-free Solder Joints · 2005-09-22 · Creep Properties of Lead-free Solder Joints Materials Science Division Lawrence Berkeley National Laboratory Department

Materials Science DivisionLawrence Berkeley National Laboratory

Department of Materials Science and EngineeringUniversity of California at Berkeley

1 2 3 4 5 6 7 8 910 20 30 4010-8

10-7

10-6

10-5

10-4

10-3

10-2

10-1

100

2(all)n-value

St

rain

rate

Shear Stress(MPa)

95?C130?C

60?C

n=4.7

n=5.1

n=3.9

n=6.8n=7.6

n=11.5

SnAg: Shear Stress vs. Shear Strain rate

Page 11: Creep Properties of Lead-free Solder Joints · 2005-09-22 · Creep Properties of Lead-free Solder Joints Materials Science Division Lawrence Berkeley National Laboratory Department

Materials Science DivisionLawrence Berkeley National Laboratory

Department of Materials Science and EngineeringUniversity of California at Berkeley

SnInAg: Shear Stress vs. Shear Strain rate

1 2 3 4 5 6 7 8 910 20 30 4010-8

10-7

10-6

10-5

10-4

10-3

10-2

10-1

100

3(all)n-value

St

rain

rate

Shear Stress(MPa)

n=6.4

n=8.9

n=10.1

n=3.4

n=7.6

n=2.7

95?C130?C

60?C

Page 12: Creep Properties of Lead-free Solder Joints · 2005-09-22 · Creep Properties of Lead-free Solder Joints Materials Science Division Lawrence Berkeley National Laboratory Department

Materials Science DivisionLawrence Berkeley National Laboratory

Department of Materials Science and EngineeringUniversity of California at Berkeley

SnAgCu: Shear Stress vs. Shear Strain rate

1 2 3 4 5 6 7 8 910 20 30 4010-8

10-7

10-6

10-5

10-4

10-3

10-2

10-1

100

4(all)n-value

Stra

in ra

te

Shear Stress(MPa)

95?C130?C

60?C

n=5.0

n=6.0n=4.4

n=9.2

n=9.9

n=11.2

Page 13: Creep Properties of Lead-free Solder Joints · 2005-09-22 · Creep Properties of Lead-free Solder Joints Materials Science Division Lawrence Berkeley National Laboratory Department

Materials Science DivisionLawrence Berkeley National Laboratory

Department of Materials Science and EngineeringUniversity of California at Berkeley

Sn Joints vs. Sn-0.7Cu Joints

1 2 3 4 5 6 7 8 910 20 30 4010-8

10-7

10-6

10-5

10-4

10-3

10-2

10-1

100

5(all)n-value

St

rain

rate

Shear Stress(MPa)

Sn (95?C)Sn(130?C)

Sn-0.7Cu (95?C)Sn-0.7Cu (60?C)

Sn (60?C)

Sn-0.7Cu (130?C)

Page 14: Creep Properties of Lead-free Solder Joints · 2005-09-22 · Creep Properties of Lead-free Solder Joints Materials Science Division Lawrence Berkeley National Laboratory Department

Materials Science DivisionLawrence Berkeley National Laboratory

Department of Materials Science and EngineeringUniversity of California at Berkeley

Stress vs. Strain rate at 60°C

1 2 3 4 5 6 7 8 910 20 30 4010-8

10-7

10-6

10-5

10-4

10-3

10-2

10-1

100

all data at 60oC

St

rain

rate

Shear Stress(MPa)

Sn-0.7CuSn-3.5AgSn-10In-3.1Ag

Sn

Sn-3Ag-0.5Cu

Page 15: Creep Properties of Lead-free Solder Joints · 2005-09-22 · Creep Properties of Lead-free Solder Joints Materials Science Division Lawrence Berkeley National Laboratory Department

Materials Science DivisionLawrence Berkeley National Laboratory

Department of Materials Science and EngineeringUniversity of California at Berkeley

Stress vs. Strain rate at 95°C

1 2 3 4 5 6 7 8 910 20 30 4010-8

10-7

10-6

10-5

10-4

10-3

10-2

10-1

100

all data at 95oC

Stra

in ra

te

Shear Stress(MPa)

Sn-0.7CuSn-3.5AgSn-10In-3.1Ag

Sn

Sn-3Ag-0.5Cu

Page 16: Creep Properties of Lead-free Solder Joints · 2005-09-22 · Creep Properties of Lead-free Solder Joints Materials Science Division Lawrence Berkeley National Laboratory Department

Materials Science DivisionLawrence Berkeley National Laboratory

Department of Materials Science and EngineeringUniversity of California at Berkeley

Stress vs. Strain rate at 130°C

1 2 3 4 5 6 7 8 910 20 30 4010-8

10-7

10-6

10-5

10-4

10-3

10-2

10-1

100

all data at 130oC

St

rain

rate

Shear Stress(MPa)

Sn-0.7CuSn-3.5AgSn-10In-3.1Ag

Sn

Sn-3Ag-0.5Cu

Page 17: Creep Properties of Lead-free Solder Joints · 2005-09-22 · Creep Properties of Lead-free Solder Joints Materials Science Division Lawrence Berkeley National Laboratory Department

Materials Science DivisionLawrence Berkeley National Laboratory

Department of Materials Science and EngineeringUniversity of California at Berkeley

Sn: Data normalized separately for high and low stress

* G=16302-40.5T(oC) *ignore abnormal three data points in the middle of 60oC data

10-4 10-3103

105

107

109

1011

1013

Q=65kJ/moln=7.7

Linear Fit for highbestQ65_B on linearized scales.yscale(Y) = A + B * xscale(X)where scale() is the current axis scale function.

Parameter Value Error------------------------------------------------------------A 30.59578912 1.66987798B 7.65551495 0.5125511------------------------------------------------------------

R SD N P------------------------------------------------------------0.99115368 0.13191349 6 0.00011704------------------------------------------------------------

Linear Fit for lowbestq85_B on linearized scales.yscale(Y) = A + B * xscale(X)where scale() is the current axis scale function.

Parameter Value Error------------------------------------------------------------A 27.05320746 0.70435624B 5.83229439 0.19952462------------------------------------------------------------

R SD N P------------------------------------------------------------0.99824909 0.02774625 5 <0.0001------------------------------------------------------------

Sn

Q=85kJ/moln=5.8

5(all)normalized

(dγ/d

t)(T/

G)e

xp(Q

/kT)

τ/G

Page 18: Creep Properties of Lead-free Solder Joints · 2005-09-22 · Creep Properties of Lead-free Solder Joints Materials Science Division Lawrence Berkeley National Laboratory Department

Materials Science DivisionLawrence Berkeley National Laboratory

Department of Materials Science and EngineeringUniversity of California at Berkeley

SnCu: Data normalized separately for high and low stress

10-4 10-3103

105

107

109

1011

1013

Q=85kJ/moln=8.9

Linear Fit for highbestQ85_B on linearized scales.yscale(Y) = A + B * xscale(X)where scale() is the current axis scale function.

Parameter Value Error------------------------------------------------------------A 37.6043741 1.94970366B 8.93998794 0.59572225------------------------------------------------------------

R SD N P------------------------------------------------------------0.98481205 0.17253109 9 <0.0001

Linear Fit for lowbestQ90_B on linearized scales.yscale(Y) = A + B * xscale(X)where scale() is the current axis scale function.

Parameter Value Error------------------------------------------------------------A 19.51329522 1.48199311B 3.48933532 0.41021243------------------------------------------------------------

R SD N P------------------------------------------------------------0.96095021 0.1098452 8 0.00014454------------------------------------------------------------

Sn-Cu

Q=90kJ/moln=3.5

1(all)normalized

(dγ/d

t)(T/

G)e

xp(Q

/kT)

τ/G* G=16302-40.5T(oC)

Page 19: Creep Properties of Lead-free Solder Joints · 2005-09-22 · Creep Properties of Lead-free Solder Joints Materials Science Division Lawrence Berkeley National Laboratory Department

Materials Science DivisionLawrence Berkeley National Laboratory

Department of Materials Science and EngineeringUniversity of California at Berkeley

SnAgCu: Data normalized separately for high and low stress

* G=16302-40.5T(oC)

10-4 10-3103

105

107

109

1011

1013

Q=75kJ/moln=10.7

Linear Fit for highbestQ75_B on linearized scales.yscale(Y) = A + B * xscale(X)where scale() is the current axis scale function.

Parameter Value Error------------------------------------------------------------A 38.85671556 3.42953034B 10.71607452 1.12409539------------------------------------------------------------

R SD N P------------------------------------------------------------0.96853874 0.16823437 8 <0.0001------------------------------------------------------------

Linear Fit for lowbestq95_B on linearized scales.yscale(Y) = A + B * xscale(X)where scale() is the current axis scale function.

Parameter Value Error------------------------------------------------------------A 28.94647642 1.09756496B 6.59206594 0.33401804------------------------------------------------------------

R SD N P------------------------------------------------------------0.99113337 0.10584323 9 <0.0001------------------------------------------------------------

Sn-Ag-Cu

Q=95kJ/moln=6.6

4(all)normalized

(dγ/d

t)(T/

G)e

xp(Q

/kT)

τ/G

Page 20: Creep Properties of Lead-free Solder Joints · 2005-09-22 · Creep Properties of Lead-free Solder Joints Materials Science Division Lawrence Berkeley National Laboratory Department

Materials Science DivisionLawrence Berkeley National Laboratory

Department of Materials Science and EngineeringUniversity of California at Berkeley

SnAg: Data normalized separately for high and low stress

* G=16302-40.5T(oC)

10-4 10-3103

105

107

109

1011

1013

Q=75kJ/moln=10.6

Linear Fit for highbestQ75_B on linearized scales.yscale(Y) = A + B * xscale(X)where scale() is the current axis scale function.

Parameter Value Error------------------------------------------------------------A 38.66983847 4.26777359B 10.64805911 1.41418521------------------------------------------------------------

R SD N P------------------------------------------------------------0.95094443 0.24799469 8 0.00028437------------------------------------------------------------

Linear Fit for lowbestQ80_B on linearized scales.yscale(Y) = A + B * xscale(X)where scale() is the current axis scale function.

Parameter Value Error------------------------------------------------------------A 20.48530855 0.77686578B 4.54995587 0.23534619------------------------------------------------------------

R SD N P------------------------------------------------------------0.99206895 0.07182148 8 <0.0001------------------------------------------------------------

Sn-Ag

Q=80kJ/moln=4.5

2(all)normalized

(dγ/d

t)(T/

G)e

xp(Q

/kT)

τ/G

Page 21: Creep Properties of Lead-free Solder Joints · 2005-09-22 · Creep Properties of Lead-free Solder Joints Materials Science Division Lawrence Berkeley National Laboratory Department

Materials Science DivisionLawrence Berkeley National Laboratory

Department of Materials Science and EngineeringUniversity of California at Berkeley

Q-n Values from Normalized data

n Q(KJ/mole)Solders

low high low highτ/G at transition

Sn-Cu 3.5 8.9 90 85 3~4 x 10-4

Sn-Ag 4.5 10.6 80 75 7~8 x 10-4

Sn-In-Ag 5.4 9.5 100 115 6~7 x 10-4

Sn-Ag-Cu 6.6 10.7 95 75 7~8 x 10-4

Sn 5.8 7.7 85 65 3~4 x 10-4

* Based on Shear Modulus for Pure Sn, G=16302-40.5T(oC)

Page 22: Creep Properties of Lead-free Solder Joints · 2005-09-22 · Creep Properties of Lead-free Solder Joints Materials Science Division Lawrence Berkeley National Laboratory Department

Materials Science DivisionLawrence Berkeley National Laboratory

Department of Materials Science and EngineeringUniversity of California at Berkeley

Sn: Normalized data(when Q=80KJ/mole)

* G=16302-40.5T(oC) *ignore abnormal three data points in the middle of 60oC data

10-4 10-3102

104

106

108

1010

1012

Linear Fit for Q80oneline_B on linearized scales.yscale(Y) = A + B * xscale(X)where scale() is the current axis scale function.

Parameter Value Error------------------------------------------------------------A 37.28741683 2.41900461B 9.05265081 0.74248747------------------------------------------------------------

R SD N P------------------------------------------------------------0.98681141 0.19109141 6 0.00025976------------------------------------------------------------

Linear Fit for Q80oneline_B on linearized scales.yscale(Y) = A + B * xscale(X)where scale() is the current axis scale function.

Parameter Value Error------------------------------------------------------------A 26.70960208 2.00197406B 5.93326631 0.56710381------------------------------------------------------------

R SD N P------------------------------------------------------------0.98657198 0.07886247 5 0.00186413------------------------------------------------------------

Sn

Q=80kJ/mol

5(all)normalized

(dγ/d

t)(T/

G)e

xp(Q

/kT)

τ/G

Page 23: Creep Properties of Lead-free Solder Joints · 2005-09-22 · Creep Properties of Lead-free Solder Joints Materials Science Division Lawrence Berkeley National Laboratory Department

Materials Science DivisionLawrence Berkeley National Laboratory

Department of Materials Science and EngineeringUniversity of California at Berkeley

SnAgCu: Normalized data(Q=85KJ/mole)

* G=16302-40.5T(oC)

10-4 10-3103

105

107

109

1011

1013

Linear Fit for Q85oneline_B on linearized scales.yscale(Y) = A + B * xscale(X)where scale() is the current axis scale function.

Parameter Value Error------------------------------------------------------------A 40.69250029 4.23097289B 10.84431281 1.3867838------------------------------------------------------------

R SD N P------------------------------------------------------------0.95427771 0.20754884 8 0.00023084------------------------------------------------------------

Linear Fit for Q85oneline_B on linearized scales.yscale(Y) = A + B * xscale(X)where scale() is the current axis scale function.

Parameter Value Error------------------------------------------------------------A 26.15301591 1.50970796B 6.16712045 0.45944405------------------------------------------------------------

R SD N P------------------------------------------------------------0.98112296 0.14558807 9 <0.0001------------------------------------------------------------

Sn-Ag-Cu

Q=85kJ/mol

4(all)normalized

(dγ/d

t)(T/

G)e

xp(Q

/kT)

τ/G

Page 24: Creep Properties of Lead-free Solder Joints · 2005-09-22 · Creep Properties of Lead-free Solder Joints Materials Science Division Lawrence Berkeley National Laboratory Department

Materials Science DivisionLawrence Berkeley National Laboratory

Department of Materials Science and EngineeringUniversity of California at Berkeley

SnAg: Normalized data( when Q=75KJ/mole)

* G=16302-40.5T(oC)

10-4 10-3103

105

107

109

1011

1013

Linear Fit for Q75oneline_B on linearized scales.yscale(Y) = A + B * xscale(X)where scale() is the current axis scale function.

Parameter Value Error------------------------------------------------------------A 38.66983847 4.26777359B 10.64805911 1.41418521------------------------------------------------------------

R SD N P------------------------------------------------------------0.95094443 0.24799469 8 0.00028437------------------------------------------------------------

Linear Fit for Q75oneline_B on linearized scales.yscale(Y) = A + B * xscale(X)where scale() is the current axis scale function.

Parameter Value Error------------------------------------------------------------A 19.8536637 1.09701095B 4.57227197 0.33233199------------------------------------------------------------

R SD N P------------------------------------------------------------0.98451812 0.101419 8 <0.0001------------------------------------------------------------

Sn-Ag

Q=75kJ/mol

2(all)normalized

(dγ/d

t)(T/

G)e

xp(Q

/kT)

τ/G

Page 25: Creep Properties of Lead-free Solder Joints · 2005-09-22 · Creep Properties of Lead-free Solder Joints Materials Science Division Lawrence Berkeley National Laboratory Department

Materials Science DivisionLawrence Berkeley National Laboratory

Department of Materials Science and EngineeringUniversity of California at Berkeley

SnCu: Normalized data( when Q=85KJ/mole)

* G=16302-40.5T(oC)

10-4 10-3104

106

108

1010

1012

1014

Linear Fit for Q85oneline_B on linearized scales.yscale(Y) = A + B * xscale(X)where scale() is the current axis scale function.

Parameter Value Error------------------------------------------------------------A 37.6043741 1.94970366B 8.93998794 0.59572225------------------------------------------------------------

R SD N P------------------------------------------------------------0.98481205 0.17253109 9 <0.0001------------------------------------------------------------

Linear Fit for Q85oneline_B on linearized scales.yscale(Y) = A + B * xscale(X)where scale() is the current axis scale function.

Parameter Value Error------------------------------------------------------------A 19.19073465 1.74943932B 3.59317129 0.48424095------------------------------------------------------------

R SD N P------------------------------------------------------------0.94959744 0.12966829 8 0.00030813------------------------------------------------------------

Sn-Cu

Q=85kJ/mol

1(all)normalized

(dγ/d

t)(T/

G)e

xp(Q

/kT)

τ/G

Page 26: Creep Properties of Lead-free Solder Joints · 2005-09-22 · Creep Properties of Lead-free Solder Joints Materials Science Division Lawrence Berkeley National Laboratory Department

Materials Science DivisionLawrence Berkeley National Laboratory

Department of Materials Science and EngineeringUniversity of California at Berkeley

Conclusion

• Sn-rich solders show two regimes of steady-state creep behavior– nL ~ 3.5-6.5 at low stress– nH ~ 8-11 at high stress– Break at τ/G ~ 4x10-4 (Sn,SnCu), 7x10-4 (SnAgX)

• The high-stress exponent (nH) increases dramatically near room temperature– due to dominant Sn constituent

• Nonetheless, overall creep behavior is reasonably well fit by two-stage curve with Q ~ 80 KJ/mole