Microstructural and mechanical responses of Sn58Bi/Cu composite solder joints with 0.1wt.% Ni and carbon fiber addition

The effect of carbon fibers (Cf) and Ni nanoparticles addition on the melting point, microstructure, shear strength, indentation hardness and indentation creep of SnBi₅₈/Cu solder joints were explored. Composite solder with various Cf percentages (0, 0.02, 0.04 and 0.06 wt.%) and 0.1 wt.% Ni nanoparticles were prepared by solder paste stirring method. The results indicated that the adulteration of Cf and Ni nanoparticles refines the microstructure and improves the mechanical properties of Sn58Bi (SnBi₅₈)/Cu solder joints. However, the added materials have a relatively small impact on the melting point of the composite solder. Solder joints containing 0.04wt.% Cf and 0.1 wt.% Ni nanoparticles showed the best performance in all samples. Compared with SnBi₅₈/Cu solder joints, the shear strength and indentation hardness of SnBi₅₈-0.1Ni-0.04Cf/Cu solder joints was increased by 28.35% and 16.84%, respectively. Furthermore, the indentation creep decreased by 19.61%. When the addition of 0.06 wt.% Cf, there were more voids and Cf accumulation in SnBi₅₈-0.1Ni-0.06Cf/Cu solder joints, which resulting in the shear strength and indentation hardness of SnBi₅₈-0.1Ni-0.06Cf/Cu solder joints were reduced.