Abstract: A multilayer structure is fabricated by forming a conductive layer on an insulative substrate. A first conductive pattern is formed on the first conductive layer and a resist layer having a via hole therethrough is formed on the first pattern. A via lead is formed in the via hole by electrically plating a metal therein utilizing the first layer as a lead for the plating process. The resist and the exposed part of the first layer ar removed and a polyimide layer having a thermal expansion coefficient that is equal to that of the via lead is formed over the substrate. The surface of the polyimide layer is etched until the via lead top segment protrudes to a predetermined height above the surface of the etched polyimide layer. A second pattern is formed on the polyimide layer and the exposed lead segment by a plating process.

Abstract: A method of forming a coposite film over the surface of aluminum materials, for forming an aluminum oxide film over the surface of an aluminum material, and metal deposits in the aluminum oxide film so as to connect electrically with the aluminum material, in which a voltage is applied to the aluminum material immersed in a sulfuric acid solution to form an aluminum oxide film having pores over the surface of the aluminum material; then the voltage is dropped sharply to near zero while the aluminum material is immersed in the sulfuric acid solution, and a voltage of approximately 0.1 V or less is applied to the aluminum material to dissolve the aluminum oxide film forming the bottoms of the pores; and then the aluminum material coated with the aluminum oxide film is nickel-plated through electroplating to form nickel deposits in the pores of the aluminum oxide film so that the nickel deposts connect electrically with the aluminum material.