PURPOSE: To prevent contamination of a furnace in which vacuum brazing is effected and improve anti-corrosive effect by making a fin with an alloy of aluminum added with Ca and Zn.

CONSTITUTION: A fin, made of an aluminum alloy added with 0.02W3.0wt% of Ca, 1.5wt% or less of Mn, 1.3wt% or less of Mg, 1.0wt% or less of Si, 1.0wt% or less of Fe, 0.4wt% or less of Cu and 0.2wt% or less of Zr, is fixed to a heat conductive tube by vacuum brazing. Adding of Ca reduces an electric potential of the aluminum alloy and has an effect as a sacrificing anode material, thereby, prevents contamination of a furnace for the vacuum brazing. In case 3.0wt% or less of Zn is added in order to improve the effect as the sacrificing anode material, Ca, prevents vaporization of Zn in the furnace. Adding of Mn, Mg, Si, Fe, Cu and Zr increases a strength of the aluminum alloy.