Printed wiring board and method of manufacturing the same

摘要

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.