US Patent 7232610 Process for preparing metal-coated aromatic polyimide film

A metal-coated aromatic polyimide film having high peel strength between the polyimide film and the metal coat can be advantageously prepared by the steps of treating an aromatic polyimide film composed of a polyimide substrate layer of aromatic polyimide having biphenyltetracarboxylic acid units in its molecular structure coated with a polyimide surface layer of aromatic polyimide having bendable bondings in its molecular structure, with electric discharge under reduced pressure, to produce protrusions connected with each other in the form of network of chain on the surface layer, and placing plural metal films on the surface layer having the protrusions.