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AssigneeIbiden Co., Ltd.
InventorsMasaru Takada, Hiroyuki Kobayashi, Kenji Chihara, Hisashi Minoura, Kiyotaka Tsukada, Mitsuhiro Kondo
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A solder resist comprising a thermosetting resin is printed on a surface of an insulating board (7) having a conductor circuit (6). The solder resist is then heat-cured to form an insulating film (1) having a low thermal expansion coefficient. A laser beam (2) is then applied to the portion of the insulating film in which an opening is to be formed, to burn off the same portion for forming an opening (10), whereby the conductor circuit (6) is exposed. This opening may be formed as a hole for conduction by forming a metal plating film on an inner surface thereof. It is preferable that an external connecting pad be formed so as to cover the opening. The film of coating of a metal is formed by using an electric plating lead, which is preferably cut off by a laser beam after the electric plating has finished.
A printed wiring board having an insulating substrate constructed by one, two or more insulating layers, a pad for external connection arranged in an outermost layer of the insulating substrate, a conductor pattern arranged in another layer different from said outermost layer, and a hole for conductivity for electrically connecting said pad for external connection and said conductor pattern;
Dependencies are inferred from the claim text.