Patent ID: 7875809
Filing Date: 2011-01-25
Classification: H05K,Y10T

Abstract:
1. A circuit board having a high-density core layer, comprising: a core layer substrate having a plated though hole filled with a dielectric cylinder, said plated though hole having a sidewall coated with an inner electroless copper layer, and an electroplated metal layer plated on said inner electroless copper layer before being filled with said dielectric cylinder, said dielectric cylinder having an outer portion tapered toward a center portion, said outer portion being thicker than said center portion to form a depressed surface; a surface electroless copper layer covering said core layer substrate, said plated through hole and said depressed surface for connecting with said inner electroless copper layer and said electroplated metal layer; and an electroplated copper layer covering said surface electroless copper layer; wherein said electroplated copper layer and said surface electroless copper layer are patterned to expose portions of said core layer substrate and form a circuit layer on said core layer substrate and a flat copper pad covering said depressed surface of said dielectric cylinder and said plated though hole.