Patent ID: 8822830

Claim:
A multi-layer printed circuit board comprising: a first insulating layer having a first surface and a second surface on an opposite side of the first surface; a plurality of first conductor circuits forming a first conductor layer on the first surface of the first insulating layer and each having a plating layer comprising a plating material; a second conductor layer comprising a plurality of second conductor circuits formed on the second surface of the first insulating layer; a second insulating layer formed on the second conductor layer and the first insulating layer; and a plurality of third conductor circuits forming a third conductor layer on the second insulating layer on an opposite side of the second conductor layer and each having a plating layer comprising a plating material, wherein the first insulating layer has an opening and a first via hole formed in the opening of the first insulating layer, the second insulating layer has an opening and a second via hole formed in the opening of the second insulating layer, the first via hole comprises the plating material of the first conductor circuits filled to a top of the opening of the first insulating layer such that at least one of the first conductor circuits in the first conductor layer is connected to at least one of the second conductor circuits in the second conductor layer, the second via hole comprises the plating material of the third conductor circuits filled to a top of the opening of the second insulating layer such that at least one of the third conductor circuits in the third conductor layer is connected to at least one of the second conductor circuits in the second conductor layer, each of the first via hole and the second via hole has a bottom end surface facing the second conductor layer and a top end surface on an opposite end of the bottom end surface, and the top end surface of each of the first via hole and the second via hole is larger than the bottom end surface of each of the first via hole and the second via hole.