METHOD FOR FORMING METAL PLATING FILM

A method that forms a metal plating film having a thick film thickness by a solid phase method is provided. The present disclosure is a method that forms the metal plating films of a first metal and asecond metal having an ionization tendency larger than an ionization tendency of the first metal. The method includes: depositing the second metal on a surface of a copper base material to form the plating film of the second metal; and depositing the first metal on a surface of the second metal by a solid electroless plating method to form the plating film of the first metal. The solid electroless plating method in the depositing of the first metal is performed using a laminated complex. The laminated complex includes a first substitution-type electroless plating bath, a solid electrolyte membrane, a copper base material, a third metal, a second substitution-type electroless plating bath, and an insulating polymer. The first substitution-type electroless plating bath contains ions of thefirst metal. The second me