Printed wiring board
A printed wiring board includes ground layers stacked via insulator(s), a first through hole, second through holes and signal wirings, each signal wiring extending from the first through hole through the clearance between predetermined ones of the ground layers, and disposed between predetermined second through holes of the second through holes. Each of first clearances in the ground layers neighboring a layer in which the signal wiring is disposed has an outline such that a distance between the first through hole and outline of the first clearance is minimum of the signal wiring. Each of second clearances in the ground layers not adjacent to the signal wiring has an outline formed outside a circle connecting each center of second through holes centering the first signal through hole, such that the outline of second clearance does not contact with the second through holes.
1. 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.
2. The printed wiring board according to claim 1 , wherein the outline of each of the first clearances is formed in a circular shape eccentrically with respect to the center axis of the first through hole.
3. The printed wiring board according to claim 1 , wherein the outline of each of the first clearances is formed in an elliptical or oval shape eccentrically with respect to the center axis of the first through hole.
4. The printed wiring board according to claim 1 , wherein the outline of each of the first clearances is formed in a polygonal shape eccentrically with respect to the center axis of the first through hole.