A method for manufacturing a circuit board with narrow conductive traces and narrow spaces between traces includes a base layer and two first wiring layers disposed on opposite surfaces of the base layer. Each first wiring layer includes a first bottom wiring and a first electroplated copper wiring. The first bottom wiring is formed on the base layer. The first bottom wiring includes a first end facing the base layer, a second end opposite to the first end, and a first sidewall connecting the first end and the second end. The first electroplated copper wiring covers the second end and the first sidewall of the first bottom wiring.