| abstract |
A multi-layer printed circuit board including a first insulating layer, a first conductor layer having circuits on one surface of the first insulating layer, a second conductor layer having circuits on the opposite surface of the first insulating layer, a second insulating layer on the second conductor and first insulating layers, and a third conductor layer having circuits on the second insulating layer on the opposite side of the second conductor layer. The first and second insulating layers have first and second via holes formed in openings of the first and second insulating layers and made of conductive materials filling the openings such that circuits in the first and third conductor layers are connected to one or more circuits in the second conductor layer, and the first and second via holes have bottom ends facing the second conductor layer and top ends larger than the bottom ends. |