PURPOSE: To eliminate the possibility of dropping of a corrugate fin due to deviation upon brazing incorporated members in a furnace by a method wherein the configuration of the corrugate fin, which is seen from the extending direction of a heat exchange tube, is formed so as to have the shape of a hand drum, which is substantially same as the shape of a gap between neighboring heat exchange tubes.

CONSTITUTION: Both ends of a heat exchange tube 3 are connected to a tank while a corrugate fin 4 is arranged so that the corrugate fin is contacted with the upper and lower surfaces of the tuber, 3. The sectional configuration of the heat exchange tube 3 is flat and elliptical shape and the configuration of the corrugate fin 4, seen from the extending direction, is substantially the same as a hand drum whereby the deviation and movement of the corrugate fin 4 is regulated by the heat exchange tube 3 after both of the tubes and the fins are incorporated. Accordingly, the possibility of dropping of the corrugate fins 14 will never be generated upon brazing the mounting members in a furnace due to deviation of the fins 4.