Patent ID: 6426011
Filing Date: 2002-07-30
Classification: H05K

Abstract:
A method of making a printed circuit board comprising the steps of:providing a substrate having at least two opposing surfaces; providing an initial copper layer on each of said opposing surfaces; forming through holes in said substrate and through said initial copper layer, each of said through holes having inner walls; treating said substrate with a catalyst to form a catalyzed layer on said substrate, including on said inner walls of said through holes; forming a thicker copper layer by plating the treated surfaces of said substrate, including said inner walls of said through holes, with copper; filling said through holes with an insulating material; thinning said thicker copper layer on said at least one surface so that no part of said catalyzed layer is exposed through said thinned copper layer, said thinned copper layer having a thickness substantially less than that of said initial copper layer; removing any insulating material projecting from the surface of said thinned copper layer to thereby level said at least one surface; plating said at least one surface of said thinned copper layer and said insulating material with copper; and thereafter patterning the copper layer on said at least one surface to form a first wiring pattern.