A backface strain technique is introduced to examine fatigue crack initiation in solder lap joints. The technique detects the fatigue crack initiation by monitoring the backface strain at the end of the overlap. Variation of the backface strain with the development of a crack was simulated by finite element method. The simulation indicated that the backface strain at the end of the overlap reached a peak value when a fatigue crack initiated. Experimental verification was carried out in 63Sn-37Pb solder joints. The backface strain was recorded as a function of stress cycle to demonstrate the applicability of this technique. Experimental results showed that fatigue crack initiation took about half of the fatigue lifetime of the solder joints.

Issue Section:
Technical Papers
Topics:
Fatigue cracks, Solder joints, Cycles, Fatigue, Finite element methods, Fracture (Materials), Simulation, Solders, Stress
1.
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2.
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D. F.
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Thermomechanical Fatigue of Solder Joints: A New Comprehensive Test Method
,”
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4
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1989
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501
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3.
Engelmaier
W.
, and
Attarwala
A. I.
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Surface-Mount Attachment Reliability of Clip-Loaded Ceramic Chip Carriers on FR-4 Circuit Boards
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12
,
1989
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284
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296
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4.
Seyyedi
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Thermal Fatigue of Low-Temperature Solder Alloys in Insertion Mount Assembly
,”
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115
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1993
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305
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311
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5.
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6.
Imanaka
M.
,
Fukuchi
Y.
,
Kishimoto
W.
,
Okita
K.
,
Nakayama
H.
, and
Nakai
H.
, “
Fatigue Life Estimation of Adhesively Bonded Lap Joints
,”
ASME JOURNAL OF ENGINEERING MATERIAL AND TECHNOLOGY
, Vol.
110
,
1988
, pp.
350
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354
.
7.
Imanaka, M., Kishimoto, W., Okita, K., Nakayama, H., and Shiroto, M., “Fatigue Mechanisms of Adhesive Bonded Joint,” 4th Int. Conf. on Structural Safety and Reliability, Published by Int. Assoc. for Structural Safety and Reliability, 1985, pp. 713–718.
8.
Harris
J. A.
, and
Fay
P. A.
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Fatigue Life Evaluation of Structural Adhesives For Automotive Applications
,”
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, Vol.
12
, No.
1
,
1992
, pp.
9
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18
.
9.
Zhang
Z.
,
Shang
J. K.
, and
Lawrence
F. V.
, “
A Backface Strain Technique for Detecting Fatigue Crack Initiation in Adhesive Joints
,”
J. Adhesion
, Vol.
49
,
1995
, pp.
23
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36
.
10.
Carpenter
W. C.
, “
A Comparison of Numerous Lap Theories for Adhesively Bonded Joints
,”
J. Adhesion
, Vol.
35
,
1991
, pp.
55
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73
.
11.
Allman
D. J.
, “
A Theory for Elastic Stresses in Adhesive Bonded Lap Joints
,”
J. Mech. Appl. Math.
, Vol.
30
,
1977
, pp.
415
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436
.
12.
Wooley
G. R.
, and
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D. R.
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Stress Concentration Factors for Bonded Lap Joints
,”
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, Vol.
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, No.
10
,
1971
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817
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820
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13.
Renton
W. J.
, and
Vinson
J. R.
, “
The Efficient Design of Adhesive Bonded Joints
,”
J. Adhesion
, Vol.
7
, No.
3
,
1975
, pp.
175
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193
.
14.
Wang
S. S.
, and
Yau
J. F.
, “
Interface Crack in Adhesively Bonded Lap-Shear Joints
,”
Int. J. Fracture
, Vol.
19
,
1982
, pp.
295
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309
.
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