MACHINING METHOD FOR CLARIFYING HOLE OF PRINTED CIRCUIT BOARD BY USING PERMANGANATE AND CAUSTIC TREATING SOLUTION

摘要

An improved process for removing resin smeared on an interior wall of a hole in a resinous substrate and/or adhesion promoting the substrate which comprises: (a) contacting the substrate with an alkaline permanganate treating solution having a pH between about 11 and about 13 and an elevated temperature for a time period sufficient to remove the resin smear; (b) neutralizing essentially all manganese residue on the substrate; (c) contacting the substrate with an alkaline hydroxide etchant to remove the balance of manganese residue on the substrate. A metal such as copper subsequently may be electrolessly deposited in a more efficient and easily controlled manner on the resin substrate in the formation of a wire scribed circuit board or multilayer printed circuit board. In addition to resin smear removal, the process results in an improved bond between copper and the hole wall.