Abstract: A wiring substrate includes differential wirings; a first insulating layer adjacent to one side of the differential wirings, including first fiber bundles parallel to the differential wirings; a second insulating layer adjacent to another side of the differential wirings, including second fiber bundles parallel to the differential wirings and disposed by the same pitch as the first fiber bundles; a third insulating layer on the first insulating layer on a side opposite to the differential wirings, including third fiber bundles in parallel to the differential wirings; and a fourth insulating layer on the second insulating layer on a side opposite to the differential wirings, including fourth fiber bundles in parallel to the differential wirings. Intervals of the third and fourth fiber bundles are respectively narrower than intervals of the first and second fiber bundles. The differential wirings are disposed between adjacent first fiber bundles, and between adjacent second fiber bundles.

Abstract: A wiring substrate includes an insulation layer including a thermosetting resin and a reinforcement member having plural first fiber bundles and plural second fiber bundles woven together, the second fiber bundles being intersected with the first fiber bundles, and a pair of differential wirings arranged alongside each other on the insulation layer. The first fiber bundles and the second fiber bundles have a curved portion relative to a plan direction of the insulation layer in a region on which the pair of differential wirings is arranged.

Abstract: A method for manufacturing an optical waveguide in which multiple cores are embedded in a parallel-arranged fashion within a single cladding, the cores having a refractive index of light different from that of the cladding, the method includes forming the multiple cores in a state where the adjacent cores are connected by a rib, forming the cladding around the rib and the multiple cores by curing a cladding material there around, and a cutting to the rib.

Abstract: A printed wiring board manufacturing method includes weaving a glass fiber cloth with warp and weft yarns such that the warp and weft yarns are visually distinguishable at least a region. The glass fiber cloth is impregnated with a resin to fabricate a substrate. A copper foil is formed on at least one surface of the substrate to fabricate a core substrate. The copper foil is removed within the region on the core substrate to form an opening. A pitch between the warp yarns or between the weft yarns which are presented in the opening is detected. A pitch between a pair of differential wirings to be patterned is determined based on the detected pitch between the warp yarns or between the weft yarns. The pair of differential wirings is patterned on the core substrate in accordance with the determined pitch between the pair of differential wirings.

Abstract: A printed board includes an insulating body that has a flat surface and includes insulating cloth including first fibers and second fibers that cross the first fibers at right angles on the flat surface, and printed wiring including a plurality of signal lines that run parallel to each other and are laid out on the flat surface of the insulating body so that a direction of the signal lines is tilted to a direction of the first or second fibers at an angle which is determined based on board-cutting efficiency of the insulating body and a predetermined delay-time difference between the signal lines.