Abstract: In a method of manufacturing a printed circuit board, a photoresist layer is formed on a three-dimensionally molded substrate through a conductive layer. A planar photomask which is provided with a mask pattern and a light-transmissive pattern is placed in front of the photoresist layer. A parallel light beam is radiated to the photomask in order to give to the photoresist layer an exposed pattern of an intended width "L" in correspondence to the light-transmissive pattern. In the present invention, the light-transmissive pattern is configured so as to satisfy the following relations:when D=0, W/L=1,when D>0, W/L<1,wherein "W" is a width of the light-transmissive pattern for forming the exposed pattern of the intended width "L", and "D" is a distance between the light-transmissive pattern and the photoresist layer. The photoresist layer of the exposed or an non-exposed pattern is removed to leave a patterned area of the conductive layer without the photoresist layer.

Abstract: A resin-impregnated sheet material is manufactured by passing a sheet material through a vacuum space of a reduced pressure sufficiently different from ambient atmospheric pressure for sufficiently deaerating the sheet material at the vacuum space, and impregnating the thus deaerated sheet material with a resin varnish while utilizing the pressure difference between the atmosphere and the vacuum space, the sufficiently deaerated sheet material being impregnated quickly and reliably with the resin varnish to provide the resin-impregnated sheet material of high quality.