Patent ID: 7905014

Claim:
A method for manufacturing a multilayer core board comprising the steps of: (a) patterning conductive thick film provided on both surfaces of a center insulating layer to form a ground layer and a power source layer respectively having conductive portions and hole portions; (b) covering the whole of the ground layer with insulating material while filling the hole portions of the ground layer with the insulating material to form non-conductive portions, thereby forming a first insulating layer, and covering the whole of the power source layer with insulating material while filling the hole portions of the power source layer with the insulating material to form non-conductive portions, thereby forming a second insulating layer; (c) forming first via holes by using a laser so that the first via holes pass through the first insulating layer, the non-conductive portions of the ground layer and the center insulating layer and reach the conductive portions of the power source layer without exposing the conductive portions of the ground layer, while the first via holes are gradually reduced in diameter from the outer surface of the first insulating layer, forming second via holes by using a laser so that the second via holes pass from the outer surface of the second insulating layer through the second insulating layer and reach the conductive portions of the power source layer, forming third via holes by using a laser so that the third via holes pass through the second insulating layer, the non-conductive portions of the power source layer and the center insulating layer and reach the conductive portions of the ground layer without exposing the conductive portions of the power source layer, while the third via holes are gradually reduced in diameter from the outer surface of the second insulating layer, where the third via holes and the second via holes are alternately juxtaposed with one another, and forming fourth via holes by using a laser so that the fourth via holes pass from the outer surface of the first insulating layer through the first insulating layer and reach the conductive portions of the ground layer; (d) covering at least inner walls of the first to fourth via holes with conductors to form first to fourth via holes conductors; and (e) forming a first conductive layer on the outer surface of the first insulating layer so as to be electrically connected to the first and fourth via hole conductors, and also forming a second conductive layer on the outer surface of the second insulating layer so as to be electrically connected to the second and third via hole conductors.