Patent ID: 8309863

Claim:
A printed wiring board comprising: a plurality of ground layers stacked via insulator(s); a first through hole; a plurality of second through holes formed at predetermined positions along a circle concentric with a center axis of the first through hole; clearances, each forming an anti-pad, provided in an area between the first through hole and each of the ground layers; and signal wirings each extending from the first through hole through the clearance between predetermined ones of said ground layers, said signal wiring being disposed between predetermined second through holes of the second through holes, wherein, among the clearances, each of first clearances in the ground layers one layer higher and one layer lower than a layer in which the signal wiring is disposed has an outline formed such that a distance between the first through hole and the outline of each of the first clearances is minimum in a direction in which the signal wiring extends from the first through hole; wherein, among the clearances, each of second clearances in the ground layers that are not adjacent to the signal wiring has an outline formed outside a circle established by connecting each center of the second through holes centering at the center axis of the first signal through hole, such that the outline of each of the second clearances does not contact with the second through holes; and wherein the second through holes are not connected to the ground layers that are not adjacent to the signal wiring but are connected to the ground layer one layer higher and one layer lower than the layer in which the signal wiring is disposed.