Printed wiring board, and method and apparatus for manufacturing the same

摘要

In manufacturing a double-layered or a multi-layered printed wiring board, a layer of metamorphic substance, which is created by transmuting a substrate material, is formed on an inner wall of a hole during a perforation process of the substrate utilizing radiation energy. The layer of metamorphic substance prevents conductive materials constituting electrical connection formed on the inner wall of the hole from dispersing over a surface of the substrate or permeating into the substrate.