A circuit board includes a substrate defining a plurality of ground attaching holes and a plurality of first through-holes. The substrate includes a first surface and a side edge. Wherein, a plurality of parallel and spaced first conductive paths is formed on the first surface around each ground attaching hole. A first arcuate conductive portion is formed at each end of each first conductive path. An angle between each first conductive path and the side edge is 45° or 135°. The first through-holes respectively extend through the first arcuate conductive portions and electrically couple with the first conductive paths.