A resin composition includes a modified poly(phenylene ether) compound having a carbon-carbon unsaturated double bond at a molecular end, a maleimide compound having two or more N-substituted maleimide groups in the molecule, and a styrene-based polymer having a weight-average molecular weight less than 10,000.

Three-dimensional electromagnetic field analysis is performed for a plurality of positional patterns of a first wiring board internal structure model including one glass cloth on the upper side of differential lines and also for a plurality of positional patterns of a second wiring board internal structure model including one glass cloth on the lower side of differential lines to calculate skews, and the calculated skews are summed relating to a plurality of wiring board patterns configured by combining a plurality of combination patterns obtained by combining the plurality of positional patterns of the first model and a plurality of combination patterns obtained by combining the plurality of positional patterns of the second model to calculate a total skew and then a skew distribution in a wiring board having a certain line length is acquired based on the total skew.

A laser system includes a femtosecond laser; and a scanner configured to irradiate laser beams, which are outputted from the femtosecond laser on fabric, according to a graphene pattern. An electronic textile with graphene patterned on the fabric is manufactured by the laser beams. The graphene pattern and a structure of the fabric are differently determined depending on applications of the electronic textile.

A circuit board, in particular for a control device of a vehicle, includes a core made of at least two layers of resin impregnated glass textile and two conductor planes of the circuit board. The glass textile layers are disposed between the conductor planes and the conductor planes are on opposite sides of the core. The glass textile layers are each between 50 micrometers and 150 micrometers thick and have a resin content of between 58 percent by volume and 74 percent by volume. The conductor planes are each between 20 micrometers and 50 micrometers thick.

A circuit board includes an insulation layer, a signal line formed over the insulation layer and extending in a direction X, and a conductor layer formed under the insulation layer. The insulation layer has periodic dielectric-constant distribution in a direction Y orthogonal to the direction X. The conductor layer includes a slit at a position corresponding to the signal line. The slit expands an electric field produced between the signal line and the conductor layer; causes less difference in dielectric constants of the insulation layer in the vicinity of the signal line (the difference is caused by the positional relationship between the signal line and the dielectric-constant distribution of the insulation layer); and reduces difference in signal transmission speeds caused by the positional relationship.

A composite comprises a reinforcing fabric and an at least partially cured composition at least partially coating the reinforcing fabric, wherein the reinforcing fabric comprises first fibers wrapped with, woven with, or wrapped and woven with polyimide fibers, and the at least partially cured composition comprises the product of 30 to 70 weight percent of a poly(phenylene ether) having a number average molecular weight of 600 to 2000 AMU, 30 to 70 weight percent of a curable component, and a curing agent, wherein weight percent is based on the combined weight of poly(phenylene ether) and the curable component.

A glass cloth includes warp yarns and weft yarns formed by bundling in the range of 14 to 55 glass filaments having a diameter in the range of 3.0 to 4.2 m, and has a weaving density of the warp yarns and the weft yarns of 86 to 140 yarns/25 mm, a thickness of 7.5 to 12.0 m, a mass of 6.0 to 10.0 g per m.sup.2, and an average number of stages of 2.00 or more and less than 3.00, an average degree of opening, which is indicated as the geometric mean of the degree of opening of the warp yarns and the degree of opening of the weft yarns, in the range of 1.000 to 1.300, and a yarn width ratio, as the ratio of the yarn width of the warp yarns to that of the weft yarns, in the range of 0.720 to 0.960.

In an embodiment the dielectric layer comprises a fluoropolymer, a plurality of boron nitride particles, a plurality of titanium dioxide particles, a plurality of silica particles; and a reinforcing layer. The dielectric layer can comprise at least one of 20 to 45 volume percent of the fluoropolymer, 15 to 35 volume percent of the plurality of boron nitride particles, 1 to 32 volume percent of the plurality of titanium dioxide particles, 10 to 35 volume percent of the plurality of silica particles, and 5 to 15 volume percent of the reinforcing layer; wherein the volume percent values are based on a total volume of the dielectric layer.

A glass cloth comprising a glass yarn woven together, the glass yarn comprising multiple glass filaments, wherein an amount of B.sub.2O.sub.3 in a composition of the glass filaments is 15% by mass to 30% by mass, an amount of SiO.sub.2 in the composition thereof is 45% by mass to 60% by mass, and an amount of P.sub.2O.sub.5 in the composition thereof is 2% by mass to 8% by mass, and loss on ignition (LOI) of the glass cloth is 0.90% by mass to 2.0% by mass.

Even when a stiffener is omitted, the semiconductor device which can prevent the generation of twist and distortion of a wiring substrate is obtained. As for a semiconductor device which has a wiring substrate, a semiconductor chip by which the flip chip bond was made to the wiring substrate, and a heat spreader adhered to the back surface of the semiconductor chip, and which omitted the stiffener for reinforcing a wiring substrate and maintaining the surface smoothness of a heat spreader, a wiring substrate has a plurality of insulating substrates in which a through hole whose diameter differs, respectively was formed, and each insulating substrate contains a glass cloth.