A prepreg including: a thermosetting resin composition (C) containing a thermosetting resin (A) and an inorganic filler (B); and a glass cloth (D) impregnated or coated with the thermosetting resin composition (C); wherein the glass cloth (D) satisfies the following expressions (I) to (III),
(x+y)95(I)
1.9<(X+Y)/(x+y)(II)
t<20(III) wherein the glass cloth (D) is defined by X (threads/inch) representing number of warp yarn per inch; Y (threads/inch) representing number of weft yarn per inch; x (threads) representing number of filament per the warp yarn; y (threads) representing number of filament per the weft yarn; and t (m) representing a thickness, and wherein the content of the inorganic filler (B) in the thermosetting resin composition (C) is from 110 to 700 parts by mass based on 100 parts by mass of the thermosetting resin (A).

A printed wiring board includes a core substrate, a first build-up layer, and a second build-up layer. Each build-up layer includes a first insulating layer including reinforcing material, a second resin insulating layer not containing reinforcing material, a first via conductor through the first insulating layer, and a second via conductor through the second insulating layer such that the top diameter of the first via conductor is substantially equal to the top diameter of the second via conductor and that the bottom diameter of the first via conductor is smaller than the bottom diameter of the second via conductor. The conductor layer on the first insulating layer includes a metal foil, a seed layer and an electrolytic plating film. The conductor layer on the second insulating-layer includes a seed layer and an electrolytic plating film and has thickness substantially equal to thickness of the conductor layer on the first insulating-layer.

New glass compositions and applications thereof are disclosed. A glass composition as described herein can include 50 to 55 weight percent SiO.sub.2, 17 to 26 weight percent B.sub.2O.sub.3, 13 to 19 weight percent Al.sub.2O.sub.3, 0 to 8.5 weight percent MgO, 0 to 7.5 weight percent ZnO, 0 to 6 weight percent CaO, 0 to 1.5 weight percent Li.sub.2O, 0 to 1.5 weight percent F.sub.2, 0 to 1 weight percent Na.sub.2O, 0 to 1 weight percent Fe.sub.2O.sub.3, 0 to 1 weight percent TiO.sub.2, and 0 to 8 weight percent of other constituents. Also described herein are glass fibers formed from such compositions, composites, and articles of manufacture comprising the glass compositions and/or glass fibers.

Generally, the present disclosure provides example embodiments relating to a printed circuit board (PCB). In an embodiment, a structure includes a PCB including insulating layers with respective metal layers being disposed therebetween. Each of first layers of the insulating layers includes a first fiberglass content. A second layer of the insulating layers has a second fiberglass content less than the first fiberglass content. For example, in some embodiments, the second insulating layer does not include a fiberglass matrix.

New glass compositions and applications thereof are disclosed. A glass composition as described herein can include 50 to 55 weight percent SiO.sub.2, 17 to 26 weight percent B.sub.2O.sub.3, 13 to 19 weight percent Al.sub.2O.sub.3, 0 to 8.5 weight percent MgO, 0 to 7.5 weight percent ZnO, 0 to 6 weight percent CaO, 0 to 1.5 weight percent Li.sub.2O, 0 to 1.5 weight percent F.sub.2, 0 to 1 weight percent Na.sub.2O, 0 to 1 weight percent Fe.sub.2O.sub.3, 0 to 1 weight percent TiO.sub.2, and 0 to 8 weight percent of other constituents. Also described herein are glass fibers formed from such compositions, composites, and articles of manufacture comprising the glass compositions and/or glass fibers.

A printed wiring board includes a core substrate, a first build-up layer, and a second build-up layer. Each build-up layer includes a first insulating layer including reinforcing material, a second resin insulating layer not containing reinforcing material, a first via conductor through the first insulating layer, and a second via conductor through the second insulating layer such that the top diameter of the first via conductor is substantially equal to the top diameter of the second via conductor and that the bottom diameter of the first via conductor is smaller than the bottom diameter of the second via conductor. The conductor layer on the first insulating layer includes a metal foil, a seed layer and an electrolytic plating film. The conductor layer on the second insulating-layer includes a seed layer and an electrolytic plating film and has thickness substantially equal to thickness of the conductor layer on the first insulating-layer.

An electronic device has a device part 10; and a fiber member 30 for joining the device part 10 to another member other than the device part included in the electronic device.

There are provided a laminate and the like and a circuit board including the same that exhibit an excellent low dielectric property by a non-conventional new approach. The laminate according to an embodiment of the present invention is a laminate used for a core layer of a circuit board, in which the laminate does not include a buildup layer, the laminate is obtained by laminating a plurality of prepregs including a fiber base material layer and a resin layer (A) so that the prepregs are in direct contact with each other, the resin layer (A) contains an inorganic filler and hollow resin particles, and the hollow resin particles are contained in the resin layer (A) in an amount of 1% by weight to 50% by weight with respect to the total amount of the resin layer (A).

A fluoride-based resin prepreg and a circuit substrate using the same are provided. The fluoride-based resin prepreg includes 100 PHR of a fluoride-based resin and 20 to 110 PHR of an inorganic filler. Based on a total weight of the fluoride-based resin, the fluoride-based resin includes 10 to 80 wt % of polytetrafluoroethylene (PTFE), 10 to 50 wt % of fluorinated ethylene propylene (FEP), and 0.1 to 40 wt % of perfluoroalkoxy alkane (PFA). The circuit substrate includes a fluoride-based resin substrate and a circuit layer that is formed on the fluoride-based resin substrate.

Generally, the present disclosure provides example embodiments relating to a printed circuit board (PCB). In an embodiment, a structure includes a PCB including insulating layers with respective metal layers being disposed therebetween. Each of first layers of the insulating layers includes a first fiberglass content. A second layer of the insulating layers has a second fiberglass content less than the first fiberglass content. For example, in some embodiments, the second insulating layer does not include a fiberglass matrix.