Effect of Ni on the microstructure and properties of Sn-6.5Zn-3.0Bi solders

Abstract

ABSTRACT In this work, Sn-6.5Zn-3.0Bi-xNi solder were prepared using the covering agent smelting method. The effect of the addition of different contents of Ni on the microstructure, melting properties, corrosion resistance, and wettability of Sn-6.5Zn-3.0Bi lead-free solder was investigated. The results showed that the addition of Ni forms intermetallic compounds(IMCs) Ni5Zn21 and Ni3Sn4 with Zn and Sn, respectively, which gradually decreased the number of Sn-Zn eutectic regions and needle-like Zn phases in the microstructure until almost none, which can significantly refine the microstructure. However, with the increase of Ni content, the number of IMCs gradually increased and aggregated within the range of Ni addition, which made the coarsening of the solder microstructure, but the size of the IMCs only increased slightly. The addition of Ni caused two peaks in the DSC curve, the peak temperature of the second peak and melting range of solders both showed a sudden increase and a slow increase with the increase of Ni content. The corrosion resistance and wettability of the solder were the best when the Ni content was 0.1 wt.%.