Patent ID: 7557304

Claim:
A multilayer printed circuit board, comprising: a central core comprising one or more layers of dielectric laminate interleaved with two or more metal layers; a first dielectric layer laminated to one side of the central core; a second dielectric layer laminated to the other side of the central core; a plurality of closed vias in the central core, each comprising a circular cavity having a first diameter formed into one side of the central core and not penetrating one of said two or more metal layers on an opposing side of the central core, an aperture having a diameter less than the first diameter in the one of said two or more metal layers on the opposing side of the central core, the aperture and the cavity forming a pathway that penetrates completely through the central core from one side to another, and metal plating on walls of the pathway to substantially close the aperture and electrically connect the one of said two or more metal layers on the opposing side to another one of said two or more metal layers on the one side; approximately one half of the plurality of closed vias situated such that the closed aperture faces the first dielectric layer and a remainder of the plurality of closed vias situated such that the closed aperture faces the second dielectric layer; resin from the second dielectric layer filling the circular cavities of the approximately one half of the plurality of closed vias, and resin from the first dielectric layer filling the circular cavities of the remainder of the plurality of closed vias; and wherein the total amount of resin migrated from each of the dielectric layers into the closed via cavities is approximately equal.