Patent ID: 6127633
Filing Date: 2000-10-03
Classification: H05K

Abstract:
A multilayer print circuit board comprising:a substrate being electrically insulative;a first circuit pattern provided on at least one surface of the substrate;an insulation layer provided on the substrate to overlay the first circuit pattern, the insulation layer comprising a resin composed of a bisphenol A epoxy, calcium carbonate powder and polybutadien as a shock resistant agent, wherein said calcium carbonate powder has an average particle size of 2 to 4 .mu.m being dispersed in the resin, a weight ratio of 15 to 35 weight parts of calcium carbonate powder to 100 weight parts of resin and wherein said polybutadien has a weight ratio of 10 to 20 weight parts of polybutadien to 100 weight parts of resin;a blind hole provided in the insulation layer so as to reach the first circuit pattern for exposing a surface of the first circuit pattern, the inner wall of the blind hole having a V-letter tapered shape geometry;a second circuit pattern provided on the insulation layer and on the inner wall of the blind hole so as to electrically connect the first circuit pattern to the second circuit pattern through the blind hole; andwherein said insulation layer and said blind hole have a roughened surface formed by application of an oxidizing agent in which the calcium carbonate is soluble and in which the bisphenol A epoxy is insoluble with said oxidizing agent comprising potassium permanganate and caustic soda.