Deformation of solder joint under current stressing and numerical simulation - II

In this paper, the Moiré interferometry technique is used to measure the in situ displacement evolution of lead-free solder joint under electric current stressing. Large amounts of deformation were observed in the solder joint under high density (above 5000 A/cm²) current stressing. The deformation was found to be due to electromigration in the solder joint and an electromigration constitutive model was applied to simulate the deformation. Both the experimental observations and finite element method (FEM) simulation results indicate that, in addition to the current density level, the current density distribution within the solder joint has a great effect on the displacement development in the solder joint under current stressing. Specifically, greater non-uniformity in current density leads to greater normal deformations within the solder joint in this test module. This is the second part of a series of papers reporting on the deformation of solder joints under current stressing.