Influence of Ni addition on the mechanical properties of Bi-5Sb-8Sn solder alloys

In this paper, the microstructures of solder alloys were improved by adding trace elements of Ni to BiSbSn solder to enhance Bi-based solder alloys mechanical properties. The spreading areas, tensile strengths and shear strengths of the Bi-5Sb-8Sn-xNi solders with various Ni contents were characterised. The results revealed that after Ni was added to the BiSbSn solder, two new phases occurred: Ni3Sn4 and NiSb2. When the Ni content was 1%, the solder tensile strength was at the highest. When the Ni content was less than 3%, the shear strength increased as the Ni content increased. When the Ni content was more than 3%, the shear strength decreased gradually, primarily owing to the large amounts of impurities and pores introduced by the internal aggregation effect. In summary, when the Ni content was between 1 and 3%, the solders had the most-usable overall properties.