Mechanical performance of advanced multicomponent lead-free solder alloy under thermal aging

Reliability of lead-free solders, used in harsh conditions such as in automotive, is still a serious concern. Simultaneous additions of multiple alloying elements like Bismuth (Bi), Antimony (Sb), Nickel (Ni) etc. to conventional Sn-Ag-Cu (SAC) based solders have recently been investigated to improve their reliability. The additional elements can bring about the improvements through solid solution and precipitation strengthening. In this study, the effects of simultaneous additions of Bi, Sb and Ni to SAC 305 solder on the evolution of microstructure and mechanical properties of the solder under thermal aging at 125 °C for up to 1008 h are investigated. Superior microstructural stability and improved mechanical strength of the multicomponent alloy at long aging time and its fracture behavior are discussed.