ELECTROPLATING METHOD FOR MAKING COPPER LAYER UNIFORM

摘要

PROBLEM TO BE SOLVED: To provide an electroplating method for depositing sufficiently uniform copper on a corner and a wall surface of through holes of a printed circuit board.SOLUTION: There is provided a method of conducting copper deposition having high throwing power by adding 5 to 100 ppb of 3-mercapto sulphonic acid and a salt thereof or a mixture thereof to a copper electroplating composition containing one or more brightener or one or more leveler. There is provided a method including impregnating a substrate into the electroplating composition, where the substrate has a plurality of through holes and knee and wall face of the plurality of through holes are coated by a first copper layer, and electroplating a sufficiently uniform second copper layer on a first copper layer of the knee and wall surface of the plurality of through holes, where throwing power of the knee is 80% or more and throwing power of the wall face of the plurality of through holes is 80% or more.SELECTED DRAWING: None