Patent ID: 8198549

Claim:
A multi-layer wiring circuit board comprising: an insulating base member having a top surface and a bottom surface; a multi-level wiring structure provided in the insulating base member and including a lower-level wiring and an upper-level wiring over the lower-level wiring, each of the lower-level wiring and the upper-level wiring being buried in the insulating base member, the lower-level wiring including a first wiring layer and a second wiring layer, and the upper-level wiring including a third wiring layer; a first blind via-hole extending from the top surface of the insulating base member toward the bottom surface with a first depth so that the first blind via-hole is in contact with and terminates at the first wiring layer of the lower-level wiring; a second blind via-hole extending from the top surface of the insulating base member toward the bottom surface with the first depth so that the second blind via-hole is in contact with and terminates at the second wiring layer of the lower-level wiring; a third blind via-hole adjacent to the second blind via-hole and extending from the top surface of the insulating base member toward the bottom surface with a second depth that is smaller than the first depth, so that the third blind via-hole is in contact with and terminates at the third wiring layer; and the lower-level wiring further including a plurality of fourth wiring layers that run between the first and second blind via-holes while overlapping with the third blind via-hole with an intervention of a part of the insulating base member.