Method for forming a metal film on the surface of a substrate metal

摘要

A method for forming a metal film on the surface of a substrate metal, which comprises soaking a substrate metal or a non-metal support carrying the substrate metal thereon in a solution of a metal salt in a high boiling point solvent under heating conditions, characterized in that the metal salt is a salt of the metal to be formed on the surface of the substrate metal with an acidic substance selected from an organic carboxylic acid, a rosin and a rosin derivative. The metal is precipitated from the solution exclusively on the surface of the substrate metal without forming any solid metal particle in the solution or on the substrate metal. Thus, the method is applicable to the formation of a soldering alloy as a film on the surface of a substrate metal without leaving thereon any free metal particle which may cause short circuits in electronic circuits. The method can thus be applied advantageously to the manufacture of electronic elements having a metal film thereon and high density printed circuits, and thus is also useful in the field of electronic industry.