Wiring substrate

A wiring substrate, comprising:

• a core substrate;
• a first build-up part formed on a first surface of the core substrate and comprising a plurality of insulating layers and a plurality of conductor layers;
• and
• a second build-up part formed on a second surface of the core substate on an opposite side with respect to the first surface and comprising a plurality of insulating layers and a plurality of conductor layers,
• wherein the first build-up part includes a first region and a second region such that the plurality of insulating layers is extending through the first and second regions in the first build-up layer and that a number of the conductor layers in the second region is greater than a number of the conductor layers in the first region and that a distance between adjacent conductor layers in the second region is smaller than a distance between adjacent conductor layers in the first region, the conductor layers in the second region include a plurality of second wirings having a minimum wiring width and a minimum inter-wiring distance that are smaller than a minimum wiring width and a minimum inter-wiring distance of a plurality of first wirings of the conductor layers in the first region, respectively, and the insulating layers are continuous in the first region and second region.