Reexamination of Thermal Cycling Reliability of BGA Components with SNAGCU and SnPb Solder Joints on Different Board Designs

In this paper, a direct comparison was conducted between SnPb and lead-free solder joints focused on long-term thermal cycling reliability after being exposed to high-temperature aging for a long period of time using two test vehicle designs. Ball Grid Array (BGA) packages with SAC305 (Sn-3%Ag-0.5%Cu) and eutectic SnPb (63%Sn-37%Pb) were compared in this research. After the test, IMC thickness and failure modes of BGA components on the different test vehicles were investigated. The results from the post-test examination were analyzed to explain certain unexpected outcomes of the two test vehicle designs when comparing the reliability results among the two programs of tests. The results showed that for the TC1 test vehicle, SAC305 solder joints show better reliability than the SnPb solder joints; while the reliability of the SnPb solder joints outperformed the SAC305 solder joints after 6 months of high-temperature aging for the TV7 test vehicle. Meanwhile, even on the same test vehicle, the failure modes varied between components with SAC305 and SnPb solder joints.