Abstract
Copper was chosen as quaternary additions in the range of 1-5 wt% to the ternary alloy Sn-9Zn-1Bi lead-free solder alloy. X-ray diffraction analysis, scanning electron microscopy and differential thermal analysis have been carried out. Resistivity, Vickers microhardness and yield strength have been measured. The results showed that formation of Cu-Sn intermetallic compounds takes place due to additions of Cu, which affected the electrical resistivity and improved mechanical properties of this alloy. Also, addition of copper upto 2 wt% caused grain refinement and decreased the melting point of this alloy by 2 °C.