Circuit board having electrically conductive structure formed between circuit layers thereof and method for fabricating the same

Abstract

A circuit board and a fabrication method thereof. Providing the insulating layer with a first conductive layer formed thereon; wherein the insulating layer was formed on a core substrate with at least one patterned circuit layer thereon. A first resist layer is applied on a first conductive layer, forming first openings to expose the first conductive layer. A first patterned circuit layer, including conductive pads and traces, is formed in the first openings. A second resist layer is applied to cover the traces, and a conductive post is formed on each conductive pad. The first and second resist layers and the first conductive layer underneath the first resist layer are removed. A dielectric material layer is formed on the insulating layer with first patterned circuit layer, forming second openings to expose the conductive posts. A second conductive layer is formed on the dielectric material layer and in the second openings. A third resist layer is applied on the second conductive layer, forming third openings of the third resist layer to expose the second conductive layer. A second patterned circuit layer is formed in the second and third openings.