Patent attributes
Forming, in a printed-wiring board, a via sufficiently filled without residual smear, for use in an insulating layer and the size of the via to be formed. A via of a printed-wiring board comprises a first filling portion which fills at least a center portion of a hole, and a second filling portion which fills a region of the hole that is not filled with the first filling portion. An interface which exists between the second and first filling portions, or an interface which exists between the second filling portion and an insulating layer and the first filling portion has the shape of a truncated cone comprising a tapered surface which is inclined to become thinner from a first surface toward a second surface, and an upper base surface which is positioned in parallel to the second surface and closer to the first surface than to the second surface.
