A circuit board including a substrate, a conductive pattern and a solder mask layer is provided. The conductive pattern includes a pad, a tail trace and a signal trace. The tail trace connects with the edge of the pad and the signal trace connects with the edge of the pad. An angle between a portion of the signal trace neighboring the pad and the tail trace is larger than 0 degree and smaller than 180 degree. The solder mask layer is disposed on the substrate and covers a portion of conductive pattern. The solder mask layer has an opening exposing the whole pad.