Abstract: A printed wiring board includes a dielectric base plate, a circuit pattern at least on one surface of the base plate, and a solder resist film containing silicon series and/or fluorine series and covering the base plate except a desired soldering area of the circuit pattern. The solder resist film has solder repelling property to prevent bridging of solder across adjacent circuits. However, the solder repelling property apts to form dots on the solder resist film. Accordingly, at least one flux accumulating portion is formed on said one surface of the base plate to accumulate flux repelled by the solder resist film. The flux accumulating portion may be a recess and/or through-hole arranged on the surface of the solder resist film.