Patent ID: 7394026

Claim:
A multilayer wiring board comprising: a plurality of wiring layers stacked, each wiring layer having a plurality of pads and a plurality of wiring patterns, the plurality of pads being arranged in a grid pattern to correspond to an arrangement of electrodes of an electronic component to be mounted thereon, each wiring pattern being formed so that one end thereof is connected to any one of the plurality of pads and that another end thereof is drawn out to an outside from an inside of a region in which the pads are placed, wherein in the wiring layer of a first layer on which the electronic component is to be mounted, respective wiring patterns are drawn out from all of pads placed in an outermost portion of the region in which the pads are placed, drawn out from pads placed on a diagonal line in a vicinity of a corner of the relevant region, and drawn out from each pad located in a diagonal direction between adjacent rows among pads placed in rows in an internal portion of the relevant region, wherein in each of the wiring layers of second and subsequent layers, respective wiring patterns are drawn out from all of pads placed in an outermost portion of a region in which the relevant pads are placed, drawn out from among the pads electrically connected through via holes to the pads from which wiring patterns are not drawn out in the wiring layer of an upper layer, and drawn out from each pad located in a diagonal direction between adjacent rows or from pads located apart from each other by a predetermined distance in a lateral direction among pads placed in rows in an internal portion of the relevant region, wherein the predetermined distance is greater than the pad spacing in the lateral direction, where the lateral direction is a direction in which the adjoining pads are closest, and wherein the first layer and the second layer are connected by means of via holes and the second layer and a layer below a core substrate, also containing a wiring pattern, are connected by means of via holes and a through hole.