Abstract: A process for soldering aluminum fins to cooling pipes made of aluminum, copper, brass or steel to produce a cooling assembly. The fins are etched in the solution of sodium hydroxide, zinc chloride, technical urea and water and the cooling pipes are coated with a fusible alloy which is covered with a protective coating for attenuating electro-corrosion between the alloy and the aluminum fins. The aluminum fins are then mounted on the cooling pipes and soldered thereto in a thermal bath.

Abstract: An improved method is disclosed for the soldering together of the cooling assembly of automobile radiators wherein aluminum fins, a first part of the cooling assembly, are etched in a solution consisting essentially of 10 to 14% sodium hydroxide, 4 to 7% zinc cyanide, 20 to 30% technical urea with the balance water for a period of 15 to 30 seconds at a temperature of 32 .degree. to 60.degree. C prior to undergoing treatment with a protective coating and eventual soldering to cooling pipes made of copper, brass, steel or aluminum, the remainder of the cooling assembly.