HIGH-DENSITY PRINTED WIRING BOARD AND MANUFACTURE THEREOF

PURPOSE:To obtain a new wiring board to make possible the formation of a high-density wiring by a method wherein a large diameter through hole and a small diameter through hole are respectively perforated on the side of the component mounting surface of an insulating substrate and on the side of the rear of the substrate, a solder resist film is formed on one surface of the small open surface side and one surface of the component mounting surface side excepting the aperture of the large through hole and the land part on the peripheral edge of the aperture and the like. CONSTITUTION:In a printed-wiring board using an insulating substrate 20 provided with large and small two-stage diameter through holes of a large diameter through hole 6 perforated on the side of its component mounting surface and a small diameter through hole 7 perforated on the side of its rear as its base, a conductor-plated layer 8 is provided on at least the inner walls of the through holes and land parts 4 and 5 on the peripheral edges of the apertures. Moreover, a solder resist film 9 is formed on one surface of the small open surface side and one surface of the component mounting surface side excepting the aperture of the large through hole 6 and the land part 4 on the peripheral edge of the aperture of the hole 6 in such a way as to block the aperture of the above small through hole 7. Thereby, even though component terminals 10 are soldered 10 in the through holes, no solder comes out on the side of the noncomponent mounting surface. As a result, the reliability of insulation of high-density signal conductors 12 arranged on this surface is improved.