Patent ID: 9338883
Filing Date: 2016-05-10
CPC Classification: H01L,H05K

Claim Text:
1. A printed wiring board, comprising: a plurality of insulating layers laminated on each other and each comprising a resin material and a core material impregnated with the resin material, the plurality of insulating layers having first-surface sides and second-surface sides on an opposite side of the first-surface sides, respectively, and including a central insulating layer positioned in the center of the plurality of insulating layers, a plurality of first insulating layers laminated on a first side of the central insulating layer, and a plurality of second insulating layers laminated on a second side of the central insulating layer; a plurality of first-surface-side conductive layers formed on the first-surface sides of the first insulating layers, respectively; and a plurality of second-surface-side conductive layers formed on the second-surface sides of the second insulating layers, respectively, wherein the plurality of first insulating layers includes at least one first insulating layer having the core material positioned such that the core material of the first insulating layer is shifted toward the first-surface side from the center of the first insulating layer in a thickness direction of the first insulating layer, the plurality of second insulating layers includes at least one second insulating layer having the core material positioned such that the core material of the second insulating layer is shifted toward the first-surface side from the center of the second insulating layer in a thickness direction of the second insulating layer, and the plurality of first-surface-side conductive layers and plurality of second-surface-side conductive layers are formed such that the plurality of first-surface side conductive layers has the total area which is set smaller than the total area of the plurality of second-surface-side conductive layers.