Patent ID: 7488675

Claim:
A method for fabricating an IC board without a ring structure, comprising the steps of: providing a substrate; forming a metal layer on the substrate; forming at least one core through hole by drilling through the metal layer and the substrate; forming a first deposited metal layer on the metal layer and a sidewall of the core through hole; forming a first pattern photoresist layer on the first deposited metal layer, and the first pattern photoresist layer having the photoresist layer opening at above the core through hole, and the photoresist layer opening occupying a pre-set space around the edges of the core through hole; forming a layer of second deposited metal layer on the surface of the pre-set space and filling the inside of the core through hole; removing the first pattern photoresist layer; forming a layer of second pattern photoresist layer to cover the first deposited metal layer and a portion of the second deposited metal layer with the second pattern photoresist layer extending partially across the core through hole; etching the uncovered portion of the second deposited metal layer, the first deposited metal layer, and the metal layer until the substrate is exposed; and removing the second pattern photoresist layer; wherein the remaining first deposited metal layer and the remaining second deposited metal layer after etching are electrically coupled to a conductive circuit of the core through hole with the remaining second deposited metal layer forming a protruded step structure of the second deposited metal layer above the core through hole to connect the second deposited metal layer filling the inside of the core through hole to the first deposited metal layer.