Patent ID: 6653572
Filing Date: 2003-11-25
Classification: H05K

Abstract:
A multilayer circuit board having a multilayer structure, comprising:a plurality of printed wiring hoards including at least a first printed wiring board and a second printed wiring board, wherein each of said first and second printed wiring boards includes a metal core substrate having a first major surface and a second major surface which are opposite and parallel to each other; an electrically insulating layer at least partially covering each of the major surfaces; a conductive printed wiring layer formed on the surface of said electrically insulating layer and including a plurality of wiring lines; a solder resist layer partially covering the surface of said conductive printed wiring layer; and wherein each metal substrate comprises a plurality of integral metal projections made of the same metal material in a single continuous piece as that of the metal core substrate, said projections being of a predetermined height on at least one of said first major surface or said second major surface so as to provide an air gap between the adjacent printed wiring boards in said multilayer structure, wherein the metal core substrate of said first printed wiring board and the metal core substrate of said second printed wiring board are made of the same metal material with each other; and wherein said solder resist layer comprises at least one local opening for exposing metal surface at a region corresponding to at least one of said metal projections.