Patent attributes
A multilayered printed wiring board has a core substrate having a through hole opening with a radius R, a through hole structure formed at the through hole opening and including a lid-shaped conductive structure, a first interlaminar resin insulation layer formed over the core substrate and having a first via hole structure with a bottom radius r, and a second interlaminar resin insulation layer formed over the first interlaminar resin insulation layer and having a second via hole structure. The lid-shaped conductive structure is formed over the core substrate at an end portion of the through-hole opening and covering the end portion of the through-hole opening. The first via hole structure is formed on the lid-shaped conductive structure and has an electroless plated film and an electrolytic plated film. The second via hole structure has an electroless plated film and an electrolytic plated film. The first via hole has a gravity center at or beyond a radius D, where D=(R−r/3) and the radius D is measured from a gravity center of the through-hole opening, and the bottom radius r of the first via hole is larger than a bottom radius of the second via hole.
