Characteristics of Press-Soldered Copper Joints by Bi-Pb Base Solders Containing Ag and Zn

Press-Soldering is a method to make a joint at a relatively lower temperature and obtain a higher joint strength. Press-Soldering experiments at I kgf/mm2 and 3 kgf/mm2 pressure were done using Bi-Pb type solder with Ag and Zn additions to obtain a sound alloyed layer at a temperature below 350°C. Tensile strength, heat-resistivity and composition of the alloyed layers of press-soldered Cu to Cu joints were investigated. A joint which was press-soldered at 350°C with 3 kgf/mm2 pressure using a Bi-42%Pb-3%Ag-2%Zn solder showed the best result. The joint had 8 kgf/mm2 of tensile strength and the remelting temperature above 820°C. In this case, two alloyed layers were found in the joint interface. The composition of the alloyed layers were Cu-18.5%Zn-2.5%Ag and Ag-29%Zn-3.5%Cu respectively.