Wiring board and mounting structure using the same
A wiring board of the present invention includes a substrate including a woven fabric formed of a plurality of glass fibers and a resin covering the woven fabric; a plurality of through holes T penetrating through the substrate in a thickness direction thereof; and a plurality of through hole conductors adhered to inner walls of the through holes T respectively. The through holes T include a first through hole and a second through hole, and, in the woven fabric, the number of the glass fibers through which the first through hole penetrates is larger than the number of the glass fibers through which the second through hole penetrates. In the first and second through holes, portions thereof having narrowest widths are surrounded by the woven fabric, and the narrow width portion of the first through hole is smaller than the narrow width portion of the second through hole.
1. A wiring board comprising:
a substrate including a woven fabric formed of a plurality of glass fibers and a resin covering the woven fabric;
a plurality of through holes penetrating through the substrate in a thickness direction thereof; and
a plurality of through hole conductors adhered to inner walls of the through holes respectively,
wherein the through holes comprise a first through hole and a second through hole,
in the woven fabric, the number of the glass fibers through which the first through hole penetrates is larger than the number of the glass fibers through which the second through hole penetrates,
in the first through hole and the second through hole, narrow width portions thereof having narrowest widths, respectively, are surrounded by the woven fabric, and
the narrow width portion of the first through hole is smaller than the narrow width portion of the second through hole.
2. The wiring board according to claim 1 ,
wherein the first through hole and the second through hole have a shape of which the width becomes smaller from each of two principal surfaces of the substrate toward a center of the substrate.
3. The wiring board according to claim 1 ,
wherein the width of an opening of the first through hole in one of the principal surfaces of the substrate is set to 0.9 times or more and 1.1 times or less the width of an opening of the second through hole in the one of the principal surfaces of the substrate.
4. The wiring board according to claim 3 ,
wherein the width of the opening of the first through hole in the one of the principal surfaces of the substrate is identical with the width of the opening of the second through hole in the one of the principal surfaces of the substrate.
5. The wiring board according to claim 1 ,
wherein a minimum width of the first through hole in a region surrounded by the woven fabric is set to 0.5 times or more and less than 0.9 times a minimum width of the second through hole in a region surrounded by the woven fabric.
6. The wiring board according to claim 1 ,
wherein the woven fabric is formed by weaving, lengthwise and widthwise, fiber bundles formed of a plurality of glass fibers, and
the widths of the narrow width portions of the first through hole and the second through hole are smaller than the width of the fiber bundle.
7. The wiring board according to claim 1 ,
wherein a wiring layer is formed on one surface of the substrate, or wiring layers are respectively formed on two surfaces of the substrate, and
the wiring layer includes:
an insulating layer in which a via hole penetrating through the wiring layer in a thickness direction thereof is formed;
a conductive layer formed on each of a surface of the substrate or a surface of the insulating layer; and
a via conductor formed in the via hole and electrically connected to the conductive layer.
8. A mounting structure comprising:
the wiring board according to claim 1 ; and
an electronic component electrically connected to the through hole conductors.