Sensitivity study on material properties for the fatigue life prediction of solder joints under cyclic thermal loading

A computational study is presented in this paper to investigate the effect of variation in material properties on the fatigue life prediction of solder joints subjected to cyclic thermal loading. The package under investigation was a plastic quad flat pack (PQFP) with gull‐wing leads. A commercial finite element code, ABAQUS, was employed to perform a two‐dimensional plane stress analysis. While all other constituents of the PQFP assembly were assumed to be linear elastic, the solder joint was considered to be elastic‐viscoplastic. The creep model was adopted from Norton’s equation and was implemented in the finite element analysis via a user‐defined subroutine. The maximum creep strain was evaluated and incorporated into the modified Coffin‐Manson equation to estimate the life cycles under thermal fatigue. It was found that the variation in material properties could have a significant influence on the fatigue life prediction of solder joints.