Development and Properties of Sn-0.7Cu-1Zn Alloy Solder Containing BiApplied in Soft Brazing of Aluminum Wire

Sn-0.7Cu-1Zn-xBi (x=0.5, 1, 1.5, 2, mass fraction/%) alloy solder was smelted. Influence of Bi content on the melting point, conductivity and wettability of the solder was studied, and the optimal Bi content was determined. The alloy solder with the optimal content of Bi was used to braze the 1060 aluminum wire and the connection fitting, and the interface morphology, breaking force and temperature rise of the connector were studied. The results show that with increasing Bi content, the melting point of the solder decreased slightly, and the conductivity decreased; the wettability increased and then decreased. The optimal Bi content was 1.0wt%, and the solder had moderate conductivity and the best wettability. The maximum tensile force of the aluminum wire connector brazed with Sn-0.7Cu-1Zn-1Bi solder reached 83% of the calculated breaking force, which was consistent with the standard requirement. The temperature rise was 18.3% lower than that by traditional compression connection, indicating the brazing method can reduce the heat generation of the aluminum wire connector.