Patent ID: 7402760

Claim:
A multi-layer printed wiring board comprising: a core substrate having a throughhole opening; a throughhole structure formed in the throughhole opening; a first interlayer insulation layer formed over the core substrate; a first via formed in the first interlayer insulation layer and having a bottom portion having a first radius; a second interlayer insulation layer formed over the first interlayer insulation layer and the first via; and a second via formed in the second interlayer insulation layer and having a bottom portion having a second radius greater than the first radius, wherein the first via is positioned inside a circle having a radius D 1 from a gravity center of the throughhole opening, and the radius D 1 of the circle satisfies a formula: ( D 1)=( R )+( r )/3, where R represents a radius of the throughhole opening and r represents the first radius of the first via.