PRINTED WIRING BOARD AND METHOD FOR MANUFACTURING THE SAME

PROBLEM TO BE SOLVED: To provide a printed wiring board in which an interstitial via hole is easily formed thereon and which surely keeps electric connection between conductive patterns.SOLUTION: A printed wiring board comprises: a substrate having an insulation property; a first conductive pattern stacked on a surface of the substrate; a second conductive pattern stacked on a rear surface of the substrate; and an interstitial via hole passing through the first conductive pattern and the substrate. A horizontal sectional shape of the interstitial via hole at the surface side, is larger that at the rear surface side. It is preferred that the horizontal sectional shape of the interstitial via hole is enlarged within a range surrounded by the first conductive pattern. It is preferred that the interstitial via hole does not project from the surface of the first conductive pattern.