Active soldering of ZnS–SiO2 sputtering targets to copper backing plates using an Sn3.5Ag4Ti(Ce, Ga) filler metal

An Sn3.5Ag4Ti(Ce, Ga) active solder is used for joining ZnS–SiO2 ceramic sputtering targets with copper backing plates at 250 °C in air. Direct soldering using the Sn3.5Ag4Ti(Ce, Ga) metal filler has been found to be a reliable and simple technique for ZnS–SiO2 ceramic bonding with ZnS–SiO2 and copper. The shear strengths for ZnS–SiO2/ZnS–SiO2 and ZnS–SiO2/Cu joints are 6.5 and 5.2 MPa, respectively. The bonding mechanism is described, with emphasis placed on the action of a rare earth element (Ce) and the active metal reaction. The interfacial reaction between Sn3.5Ag4Ti(Ce, Ga) filler metal and copper at temperatures ranging from 120 to 200 °C is conducted and discussed.