PURPOSE: To reduce the liberation and leakage of the brazing material of a radiator assembling member and to improve heat exchange efficiency, by coating the brazing material on one or both sides of a copper or copper alloy plate.

CONSTITUTION: There are oxygen-free copper, phosphor deoxidized copper, brass, phosphor bronze, Cu-Ni-alloy, etc. as copper or a copper alloy, and there are phosphor copper solder, silver solder, brass solder, etc. as a brazing material. Above all, the oxygen-free copper is used on account of its good heat conductivity and the phosphor copper solder as the brazing material on account of its low m.p. and low cost. The preferable ratio of the thickness of the brazing material and the thickness of the copper or copper alloy is 5W25%, and the platelike brazing material is joined by press sticking on one or both surfaces of a copper or copper alloy plate, whereafter the plate is hot-rolled at 100W300°C and is then cold-rolled whereby the plate is finished to a clad plate of a prescribed size.