High-density multi-layered printed wiring board having highly reliably through hole and method of producing said printed wiring board

摘要

A high-density multi-layered printed wiring board in which a copper-clad multi-layered board has a hole having a diameter of 25 to 200 mu m and has at least three copper foil layers, wherein at least one hole is made with a laser and all connections between copper foil layers are done with a through-hole perforating through each of the copper foil layers, and a method of producing said multi-layered printed wiring board.