Modeling deformation in microelectronics BGA solder joints under high current density. Part I. Simulation and testing

In this paper, Moire interferometry technique is used to measure the in-situ displacement evolution of lead-free solder joint under electric current stressing. Large deformation was observed in solder joint under high density (10⁴A/cm²) current stressing. The deformation was found to be due to electromigration in the solder joint. An electromigration constitutive model is developed to simulate deformation of lead-free solder joint under current stressing. The simulation predicts reasonably close displacements results to Moire interferometry experimental results in both spatial distribution and time history evolution, which indicates that the electromigration model is reasonably good for predicting the mechanical behavior of lead-free solder alloy under electric current stressing. This is the first part of the papers reporting the deformation of solder joint under current stressing. More experimental results are reported in the second paper.