A circuit board includes: a substrate; a conductive pattern disposed on a surface of the substrate; a lower insulation layer disposed on the conductive pattern to cover the conductive pattern except for an opening, through which the conductive pattern is partially exposed from the lower insulation layer; a conductor disposed on the lower insulation layer and connecting to the conductive pattern through the opening; an upper insulation layer disposed on the conductor for covering the conductor and the lower insulation layer; and a test coupon disposed on the substrate for evaluating the conductor.