A multilayer board includes: a smooth-surfaced double-sided board having: a base material provided with a hole penetrating therethrough, a first layer wiring pattern provided on both surfaces of the base material and having a surface, and a conductive material filled in the hole, the filler having ends...http://www.google.es/patents/US5473120?utm_source=gb-gplus-sharePatente US5473120 - Multilayer board and fabrication method thereof
