Mechanical properties of Sn–0.7Cu/Si3N4 lead-free composite solder

The use of reinforcing high performance ceramic particulates in monolithic lead-free solder is one way to improve the service temperature and mechanical behavior of a solder joint. In this study, various compositions of Sn–0.7Cu/Si3N4 lead-free composite solder were fabricated via the application of powder metallurgy (PM) techniques. The influences of the Si3N4 particulates in the monolithic matrix solder on the melting point temperature (Tm), microhardness value, lap-shear strength, and surface fracture mechanisms were investigated based on the weight percentage addition used (0.5 wt%, 1.0 wt%, and 1.5 wt%). Minimal alteration of the melting point temperature of the composite solder sample was obtained. Improvements in the microhardness value and lap-shear strength were found for higher reinforcements of Si3N4 particulates, which revealed the formation of a more ductile fracture mode in the composite solder samples. The increasing addition of Si3N4 allowed the formation of homogeneous and finer dimples. Overall, the addition of Si3N4 particulates to the Sn–0.7Cu lead-free solder should be higher than 1.0 wt%, as these compositions showed superior mechanical properties.