To reduce liquid phase sintering brazing required temperature and time by adding specific metal as a metallic material for brazing.

At least two metals are selected from a group consisting of the metals of chrome, titanium, tin, nickel, tungsten, iron and cobalt and they are added to a powder alloy for welding with copper as its base material. Additionally, a water soluble high polymer substance is added with water to the brazing metal material as a binder. Hereby, weight ratios of metal elements are made; 0.005-0.05 for chrome, 0.005-0.20 for titanium, 0.000001-0.20 for tin, 0.000001-0.005 for nickel, 0.000001-0.005 for tungsten, 0-0.005 for iron and 0.000001-0.005 for cobalt.