PARTIAL PLATING METHOD USING CHEMICAL FORMING FILM AS MASKING

PURPOSE:To partially form a metal coating layer on an Al matrix having a complicated shape at a high speed, by a method wherein a metal coating part is formed on the local part of an Al surface by using metal halide and, after a chemical forming film is formed only on the Al surface, electroless plating is applied thereon. CONSTITUTION:After sticky vaseline is thinly applied to the part of the surface of an Al material, a fine powder of metal halide such as copper halide or tin halide are scattered thereon and, after th whole is heated to a temp. generating substitution reaction between metal halide and Al or more, the residue is removed by washing. By this method, the Al material locally coated with different kind metal is obtained. In the next step, the treated Al material is thrown into a treating liquid prepared by hot pure water or aqueous ammonia to 80 deg.C or more to form a dense protective boehmite coating film. Finally, coated metal is activated according to necessity and the activated Al material is immersed in an electroless plating liquid to apply plating to the Al material and the different kind metal. The plated material is thereafter washed and dried.