Patent ID: 8110749

Claim:
A printed wiring board comprising: a core layer having electrical conductivity; large-sized through holes formed in the core layer, the large-sized through holes penetrating through the core layer from a front surface of the core layer to a back surface of the core layer; a large-sized via having electrical conductivity, the large-sized via formed in a shape of a cylinder along an inward wall surface of each of all the large-sized through holes located within a specific area; a filling material filling an inner space defined in the large-sized via; a small-sized through hole formed in the filling material, the small-sized through hole penetrating through the filling material along a longitudinal axis of the large-sized through hole; and a small-sized via having electrical conductivity, the small-sized via formed in a shape of a cylinder along an inward wall surface of the small-sized through hole.