Method of fabricating a substrate with a via connection

Abstract

A method of fabricating a substrate having a conductive layer on opposing sides, with the conductive layers interconnected by a conductive via. The inventive method uses a dielectric substrate having a conductive layer deposited or laminated onto one or both of the substrate's opposing surfaces. For the situation of a metal layer on one side of the substrate, a laser drill is used to drill blind vias through the dielectric, stopping at the substrate/conductive layer interface. An electrolytic plating process is used to fill the via by establishing an electrical connection to the conductive layer. A second conductive layer may be deposited or laminated to the other surface of the substrate. If the starting structure has a conductive layer on both sides of the substrate, the drill is controlled to bore through the upper conductive layer at a comparatively high power and then continue at a lower power through the substrate. The blind vias drilled through the upper conductive layer will be plated during the via filling stage, and may be planarized, if desired, to provide a planar surface between the filled via sites and the surrounding conductive layer.

Dependencies are inferred from the claim text.