PURPOSE: To contrive to prevent a heat exchanger from being corroded and to enhance the durability and reliability of the heat exchanger by a method wherein plating film, onto which coating film is formed, is formed onto the surface of copper heat transfer member.

CONSTITUTION: Plating films 5, the major component of each of which consists of Ni, Pb and the like and the melting point of each of which is 300°C and above, are formed onto the surface of copper heat transfer member 4 consisting of a drum having a combustion chamber therein, a heat exchange tube and heat absorbing fins. Further, coating films 6 are formed onto the plating film 5 by applying paint, which is prepared by dispersing organic polymer having polyborosiloxane as its major component and at least one kind of filler selected from the group of fine powder consisting of aluminum oxide, nickel oxide, silicon carbide and boron nitride with solvent. As a result, the corrosion of the corner heat transfer member is eliminated and the remarkable improvement of the durability of a heat exchanger is obtained.