Bi-Ag-Zn series lead-free solder and preparation method and application thereof

The invention discloses a Bi-Ag-Zn series lead-free solder and a preparation method and application thereof, and the Bi-Ag-Zn series lead-free solder is composed of the following components of, by mass, 3%-5% of Ag, 1%-3% of Zn, 0%-0.5% of Al, 0%-6% of Sb, 0%-3% of Cu and the balance Bi. According to the preparation method, the refined structure is obtained through immediate quenching after smelting, then the solder rough blank is subjected to homogenization treatment, components are made to be uniform and free of segregation, and finally quenching is conducted, so that atoms in the solder are arranged in a highly-ordered mode, precipitated phases are evenly distributed in a base body in a fine needle shape, and therefore the high-quality solder is obtained. Under the synergistic effect of the components and the preparation method, fine and uniform precipitated phases such as an AgZn phase and AgZn3 are finally obtained and uniformly distributed in a matrix in a needle shape, so that the Bi-Ag-Zn-based lead-f