Method for forming a plated microvia interconnect

Abstract: A method for forming a plated microvia interconnect. An external dielectric layer (EDL) is mounted on a substrate in direct mechanical contact with a conductive element thereon. An opening in the EDL exposes the conductive element and create a microvia in the EDL. A sidewall and bottom wall surface of the microvia are treated to promote adhesion of copper and are plated with a layer of copper that includes a copper layer on a copper seed layer and is in direct mechanical and electrical contact with the conductive element. A wet solder paste is deposited on the layer of copper to overfill a remaining portion of the microvia. The solder paste is reflowed to form a solder bump in and over the remaining portion of the microvia to form the plated microvia interconnect. A stiffener is attached to the EDL using a first adhesive. (end of abstract)