Evaluation of board level reliability of Pb-free PBGA solder joints

The present study is intended to evaluate the board level reliability of PBGA assemblies under thermal and mechanical loading. The main objective is to characterize the reliability of Pb-free solder joints with various assembly conditions. For the purpose of benchmarking, specimens with conventional Sn-Pb eutectic solder are tested in parallel as well. During the course of this study, a five-leg experiment is designed with various combinations of solder materials and peak reflow temperatures. The reliability tests include temperature cycling, three-point bending, and random vibration. It is found that the Pb-free solder joints have a much longer thermal fatigue life than the 63Sn-37Pb solder. Although there is no significant difference, the 63Sn-37Pb solder joints seem to perform slightly better than the Pb-free solder under the mechanical loading.