PURPOSE: To improve the corrosion resistance thereof by a method wherein the U-bent part of a belt-type tube is coated by a sacrificial corrosion member of a material same as a corrugated fin in the heat exchanger for the cooler for a vehicle or the like.

CONSTITUTION: The tube 1 is made by extruding the aluminum alloy material into the band-type tubular construction having a porous section and forming it into multi-stage meandering configuration. The corrugated fin 4 is made by pinching a core member of an alloy plate, which is poor in an electrode potential then the tube 1 is clad with a soldering member on both surfaces thereof, between the neighboring tubes. The terminals of the corrugated fins 4, ... are extended to the inner and outer surfaces of respective bent parts 1', ... of the tube 1 and are coated. Thereafter, when they are heated in a vacuum furnace, the tube 1 and the fins 4, ... are integrated by the soldering member clad on the corrugated fins 4. Thus the corrosion resistance of the heat exchanger may be improved as a whole by the sacrificial corrosion effect of the corrugated fins.