Patent ID: 8440916

Claim:
A method of fabricating a substrate core structure comprising: providing a starting insulating layer; providing a first patterned conductive layer on one side of the starting insulating layer, and a second patterned conductive layer on another side of the starting insulating layer each of the first patterned conductive layer and the second patterned conductive layer defining conductive layer openings through which a set of via openings will be formed; providing a first supplemental insulating layer onto the first patterned conductive layer, and a second supplemental insulating layer onto the second patterned conductive layer; providing a first supplemental conductive layer on said first supplemental insulating layer; laser drilling said set of via openings through said second supplemental insulating layer, through said conductive layer openings in said second patterned conductive layer, through said starting insulating layer, through said conductive layer openings in said first patterned conductive layer, through said first supplemental insulating layer, and to, but not through, said first supplemental conductive layer; filling the set of via openings with a conductive material to provide a set of conductive vias wherein said set of conductive vias includes at least one conductive via which electrically connects said first patterned conductive layer with said second patterned conductive layer; after filling the set of via openings, patterning said first supplemental conductive layer to provide a first supplemental patterned conductive layer on the first supplemental insulating layer; and after laser drilling the set of via openings, providing a second supplemental patterned conductive layer onto the second supplemental insulating layer, the set of conductive vias contacting the first supplemental patterned conductive layer at one side thereof, and the second supplemental patterned conductive layer at another side thereof.