Microstructural evolution and shear performance of AuSn20 solder joint under gamma-ray irradiation and thermal cycling

Owing to the excellent stability and mechanical strength, AuSn20 solder is of particular importance to the die attachment in aerospace power modules. An elevated requirement was put forward to improve the performance of solder joints for next-generation aerospace electronics. To this context, the microstructural evolution and mechanical performance of AuSn20 solder joints under independent γ-ray irradiation and thermal cycling were investigated in this work. The experimental results reveals that the shear forces of AuSn20 micro-joints were reduced by 17.5% and 25.3% after 1000 h of γ-ray irradiation and 200 thermal cycles, respectively, which are caused by the increase of interfacial IMC (intermetallic compound) layers and voids. Generally, the experimental data presented here are highly prospective because it provides new insights for the solder joint reliability in space environment, which could advance the research progress of aerospace devices without RHBD (radiation hardening by design) and ATCS (active thermal control system).