Mechanical shock behavior of Sn-3.9Ag-0.7Cu and Sn-3.9Ag-0.7Cu-0.5Ce solder joints.

Sn–Ag–Cu lead-free solder have been shown to have inferior mechanical shock resistance to that of Pb–Sn alloy. Sn-rich solders containing rare earth elements have been shown to have superior mechanical properties when compared to conventional Sn–Ag–Cu solder, in terms of strain-to-failure. In this paper, we report on the mechanical shock behavior of Sn–3.9Ag–0.7Cu and Ce-containing Sn–3.9Ag–0.7Cu alloys over the strain rate range of 10−3–12s−1. Failure mechanisms of solders in different strain regimes are investigated based on the fractography analysis. It will be shown that the shock performance of Sn–3.9Ag–0.7Cu solders can be improved with addition of trace amount of Ce in the solder matrix controlled regime. The role of CeSn3 intermetallics on the enhanced dynamic performance is discussed.