Unusual Wetting Phenomenon of Liquid Bi on Solid Cu and Its Application to Joining

An unusual wetting phenomenon of liquid Bi on a surface-porous copper has been studied. A surface-oxidized copper substrate was reduced at 473K in H_2 to prepare a porous metallic layer at the surface, and the wetting behavior of liquid Bi on this metallic layer was investigated. The unusual wetting behavior of liquid Bi was observed on the surface-porous copper substrate. This unusual wetting phenomenon of liquid Bi was then applied in the joining of copper wire with the surface-porous copper substrate. Bonding was successfully achieved with a minimized weld overlay at the joining point.