Effects of Graphene Nanosheets on the Wettability and Mechanical Properties of Sn-0.3Ag-0.7Cu Lead-Free Solder

Abstract

Low silver Sn-0.3Ag-0.7Cu (SAC0307) composite solder reinforced with graphene nanosheets (GNs) was prepared by powder metallurgy techniques, and the effects of GN content on the melting characteristics, wettability, microhardness and shear strength of the composite solder were investigated. The wettability and microhardness of the composite solder increased significantly, and the initial melting temperature decreased slightly with increasing doping content of GNs, the wettability and microhardness of the composite solder increased significantly, but the initial melting temperature decreased slightly. When the GN content reaches 0.01 wt.%, the wettability angle of the composite solder decreases by ∼ 29%. When the content of GNs reaches 0.09 wt.%, composite solder of microhardness is up to 15.3 HV, approximately 1.12 times larger than that of the un-doped SAC0307 solder. At the same time, it is also found that the shear strength of the composite solder increases with the increase of GN content. When reaching 0.05 wt.%, the shear strength is the highest (24.70 MPa) and then presents a downward trend. In addition, the fracture morphology of microscale solder joints exhibits a typical ductile fracture character to the brittle one with increasing GN content.