Patent ID: 8595927

Claim:
A method for manufacturing a printed wiring board, comprising: preparing a core substrate having a first surface and a second surface on an opposite side of the first surface; forming a penetrating hole from the first surface of the core substrate toward the second surface; forming a first conductor on the first surface of the core substrate; forming a second conductor on the second surface of the core substrate; and filling a conductive material in the penetrating hole such that a through-hole conductor connecting the first conductor and the second conductor is formed, wherein the forming of the penetrating hole includes forming a first opening portion on a first-surface side of the core substrate, forming a second opening portion from a bottom portion of the first opening portion toward the second surface, and forming a third opening portion from a bottom portion of the second opening portion toward the second surface, and the forming of the penetrating hole satisfies X 2 <X 3 ≦X 1 where X 1 represents a diameter of the first opening portion, X 2 represents a diameter of the second opening portion, and X 3 represents a diameter of the third opening portion.