Effect of Ni-coated graphene on the performance of SAC305 solder

In this paper, Ni-coated graphene nanosheets (GNS-Ni) were synthesized by an in situ chemical reduction method. Such GNS-Ni sheets, by varying their weight fractions (0.05, 0.1 and 0.2wt.%) were successfully incorporated into the SAC305 solder matrix to fabricate composite solders through the powder metallurgy processing method. The samples of composite solders were then investigated in terms of their microstructural, thermal, wettability and mechanical properties respectively. After the GNS-Ni addition to the solder alloy, the finer microstructure were observed in the solder matrix. The electrical resistivity of the GNS-Ni doped solder alloys was reduced in comparison to SAC305 solder without GNS-Ni sheets. With the increasing addition of GNS-Ni, the composite solders showed an improvement in their wetting property but an insignificant change in their melting temperature. The mechanical characterization has also been carried out, and the results indicated that the addition of 0.2wt.% GNS-Ni lead to 19.7% and 16.9% improvement in micro-hardness and shear strength respectively, when compared with that of the unreinforced solders. Furthermore, the reinforcing mechanism due to the addition of the GNS-Ni and the effects on various resultant properties was also analyzed in this study. The results in this study proved that the addition of GNS-Ni can improve not only the mechanical properties of the solder alloy, but also better the wettability without any increase of its melting point. Thus, these GNS-Ni doped composite solders can be further developed as a potential material for microelectronics assembly and packaging industry.