Patent ID: 7339118
Filing Date: 2008-03-04
Classification: H01L,H05K,Y10T

Abstract:
1. A printed wiring board comprising n conductive layers and n insulating layers, wherein said n conductive layers and said n insulating layers are interleaved wherein the conductive layers are electrically connected to one another via first and second through holes, wherein n is an odd number; wherein a first of said conductive layers is a layer on which an electronic component is to be mounted with leads for electric currents in and out of the electronic component; an n-th one of said conductive layers is an external connecting layer for connecting external connecting terminals which conduct electric currents in and out of the printed wiring board; a second to an (n−1)-th ones of said conductive layers are current transmitting layers for transmitting internal currents of the printed wiring board; each of a first to an (n−1)-th ones of said insulating layers, except for the (n+1)/2-th insulating layer, has at least one of the first through holes with a plating film formed on a wall thereof to connect the conductive layers; and a surface of the n-th conductive layer is covered with an n-th and outermost one of the insulating layers wherein a central ((n+1)/2-th) insulating layer has the second through holes, each of the second through holes having a plating film formed on a wall thereof, said plating film extending to the ones of the conductive layers adjacent the central insulating layer and connecting to a first through hole, whereby warping is prevented from occurring in the printed wiring board.