Effects of gallium on wettability, microstructures and mechanical properties of the Sn-Zn-Ag-Ga and Sn-Zn-Ag-Al-Ga solder alloys

The microstructures and mechanical properties of Sn-8.55Zn-0.5 Ag-0.45Al -yGa (wt %) and wetting behavior of Sn-8.55Zn-0.5Ag-yGa (wt %) lead-free solders were investigated. The Ga content, y, of the solders investigated were 0.5 wt % /spl sim/3.0 wt %. The results indicate that Ga plays an important role not only in the structure and wetting behavior, but also in the mechanical properties. The mechanical properties and DSC behavior were compared with that of 63Sn-37Pb and Sn-9Zn solders. Ga lowers the melting point of the Sn-8.55Zn-0.5Ag-0.45Al-yGa solders. The Sn-8.55Zn-0.5Ag-0.45Al-0.5Ga solders exhibit greater strength and better ductility than the 63Sn-37Pb.