Patent ID: 6896173

Claim:
A method for fabricating a circuit substrate, comprising the steps of: providing a circuit substrate having a first surface and a second surface, wherein the circuit substrate includes at least a first pad, at least a second pad, a first patterned solder mask layer and a second patterned solder mask layer, the first pad and the second pad are formed respectively on the first surface and on the second surface, the first pad is electrically connected to the second pad, the first patterned solder mask layer is formed on the first surface and has at least an opening exposing the first pad, and the second patterned solder mask layer is formed on the second surface and has at least an opening exposing the second pad; forming a conductive seed layer over the second surface; forming a patterned mask layer over the second surface, wherein the patterned mask layer has at least an opening exposing the conductive seed layer positioned over the second pad; electroplating a first conductive layer and a second conductive layer respectively over the first pad and over the second pad; eliminating the patterned mask layer; and patterning the conductive seed layer.