MULTILAYER PRINTED WIRING BOARD AND METHOD FOR MANUFACTURING THE SAME

摘要

An opening is made in a resin (20) with a laser to form a viahole. A copper foil (22) etched into a thin film (3 mu m) to lower the heat conductivity is used as a conformal mask, thereby making an opening (20a) in the resin (20) by fewer times of irradiation with a pulse laser beam. This prevents formation of any undercut in the resin (20) on which an interlayer resin-insulating layer is to be formed, enabling improvement in the connection reliability of the viahole.