Process for producing metal composite film

A process for producing a composite metal film, which process comprising the steps of:

• forming a thermoplastic polyimide layer on at least one surface of an insulating film;
• forming a first copper layer by electroless plating so that the first copper layer is disposed directly on said thermoplastic polyimide layer;
• and
• forming a second copper layer directly on said first copper layer by electrolytic plating, wherein
• said thermoplastic polyimide layer comprises a polyimide resin having carboxyl groups, wherein
• said thermoplastic polyimide layer is formed by applying a solvent-soluble polyimide solution on the insulating film and drying the solution, and wherein
• said thermoplastic polyimide is a polyimide obtained by polycondensation between a tetracarboxylic dianhydride component(s) including at least bicyclo[2,2,2]oct-7-ene-2,3,5,6-tetracarboxylic dianhydride and a diamine component(s) including at least a diamine having a carboxylic group(s).