Research Status and Prospect of Sn-Bi Series Low-temperature Solders

Due to low melting temperature, good wettability and high tensile strength, Sn-Bi low-temperature solders have a good prospect in the field of low-temperature brazing and they are favorable competitors to become a substitute for Sb-Pb solders. However, the brittleness caused by the Bi phase in the Sn-Bi solders and the degradation of performance due to dendrite segregation and grain coarsening during the welding process largely limit its use scenario. The development of Sn-Bi solders in recent years was reviewed, the influence of five elements such as Ag, Cu, Zn, Sb and Ni on the melting characteristics, microstructure, mechanical properties, wettability, and intermetallic compounds of Sn-Bi solders was described, the problems of different compositions of solders in the current research were pointed out, and the direction of the future research was prospected.