A generalized solder joint fatigue life model for surface mountpackages was previously published by the author. The model is based oncorrelation to measured crack growth data on BGA joints during thermalcycling. It was subsequently discovered by Anderson et. al. that theANSYSTM 5.2 finite element code used in the model had anerror in its method for calculating plastic work. It was shown thatsignificant error in life prediction could result by using a recentversion of the code where the bug has been fixed. The error comes aboutsince the original crack growth constants were derived based on plasticwork calculations that had the bug. In this paper, crack initiation andgrowth constants are recalculated using ANSYSTM 5.6. Inaddition, several other model related issues are explored with respectto the crack growth correlations. For example, 3D slice models werecompared to quarter symmetry models. Anand's constitutive model wascompared with Darveaux's constitutive model. It was shown that the crackgrowth rate dependence on strain energy density always had an exponentof 1.10+/-0.15. This is in the range of the original correlation, so theaccuracy of relative predictions should still be within+/-25%. However,the accuracy of absolute predictions could be off by a factor of 7 inthe worst case, if the analyst uses a modeling procedure that is notconsistent with that used for the crack growth correlation. The key togood accuracy is to maintain consistency in the modeling procedure
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