Design of solder joints for fundamental studies on the effects of electromigration

The continuous miniaturization of high performance electronic devices has reached a level at which current densities are large enough to make electromigration (EM) a significant issue affecting the electrical and mechanical reliability of solder joints. A new design of solder joints that controls the extent of regions experiencing relatively uniform current density, as well as regions with large current density gradient was developed. Current density distribution of this newly designed solder joint was calculated using finite element analysis (FEA), which was used to guide the characterization of EM of real solder joints. As a part of the effort in evaluating the suitability of the new joint configuration for evaluating the fundamental issues in EM, eutectic PbSn solder joints were fabricated using this design. EM effects due to applied current, current density distribution, and joint thickness of eutectic PbSn solder joints present in this joint configuration were investigated. Findings based on this new design can facilitate fundamental studies of EM issues that affect the reliability of solder joints.