LAUSR

In this study, the evolution of interfacial microstructures and mechanical properties of the joints soldered with Sn–0.3Ag–0.7Cu (SAC0307) and SAC0307-0.12Al2O3 nanoparticles (NPs) aged at 150 °C for different hours (72–840 h) were investigated. It was found the joint soldered with SAC0307-0.12Al2O3 displayed a significantly enhanced high-temperature joint reliability, reflected in a higher shear force than that of the original. This enhancement in shear force primarily benefited from the refinement in solder microstructure contributed by Al2O3 NPs. As aging time reached 840 h, a controlled growth of interfaical IMC layer resulted from the pinning effect of Al2O3 NPs contributed to the increase in shear force. Theoretical analysis showed 0.12 wt% Al2O3 NPs effectively lowered the growth constant of total interfacial IMCs (DT) from 3.19 × 10−10 to 1.02 × 10−10 cm2 s−1. Moreover, comparative studies on the corrosion resistances of SAC0307 and SAC0307-0.12Al2O3 were also conducted by electrochemical test and analyzed by electrochemical impedance spectroscopy (EIS). The results revealed SAC0307-0.12 Al2O3 solder displayed a stronger corrosion resistance (Rt; ~ 3.1 kΩ cm2 vs ~ 7.1 kΩ cm2). This is also related with the tailored microstructure, which provides more grain boundaries for the initial nucleation of passive film.