The present disclosure relates to a glass cloth, prepreg, and printed circuit board.

There is provided a glass cloth including woven glass yarns each containing a plurality of filaments, wherein a bulk dissipation factor of a glass in the glass yarns is 0.0010 or less, a tensile strength of warp yarns per thickness of the glass cloth as represented by the following formula (A) is in the range of 0.50 to 6.0:

warp direction tensile strength (N/25 mm) of the glass cloth/thickness of the glass cloth (m)(A) a coefficient of variation of the warp direction tensile strength of the glass cloth is in the range of 15% or less, and a dissipation factor of the glass cloth at 10 GHz is in the range of greater than 0 and 0.0010 or less.

A first thermal management approach involves an air flow through cooling mechanism with multiple airflow channels for dissipating heat generated in a PCA. The air flow direction through at least one of the channels is different from the air flow direction through at least another of the channels. Alternatively or additionally, the airflow inlet of at least one channel is off-axis with respect to the airflow outlet. A second thermal management approach involves the fabrication of a PCB with enhanced durability by mitigating via cracking or PTH fatigue. At least one PCB layer is composed of a base material formed from a 3D woven fiberglass fabric, and conductive material deposited onto the base material surface. A conductive PTH extends through the base material of multiple PCB layers, where the CTE of the base material along the z-axis direction substantially matches the CTE of the conductive material along the x-axis direction.

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 μm, 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 μm, 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.

Provided are a silica glass yarn and a silica glass cloth which have a signal transmission speed that is made stable through stabilization of a characteristic impedance in addition to a low dielectric constant and a low loss. The silica glass yarn has a yarn habit density of 0.10 piece/cm or less of yarn habits each having a bending point with a radius of curvature of 5 mm or less and a bending angle of 120° or less. It is preferred that the silica glass yarn have a tensile strength of 2.0 GPa or more, and silica glass filaments forming the silica glass yarn each have a breaking start strength of 80.0% or more of the tensile strength of the silica glass yarn.

A fabric-based item may include a housing that is covered in fabric. Areas of the fabric may overlap input circuitry such as button switches, touch sensors, force sensors, proximity sensors, and other sensing circuitry and may overlap other components such as light-emitting components and haptic output devices. The fabric-based item may include control circuitry that gathers user input from the input circuitry and wireless communications circuitry that the control circuitry uses to transmit remote control commands and other wireless signals in response information from the input circuitry. The fabric-based item may have a weight that is located in the housing to orient the housing in a desired direction when the housing rests on a surface. A movable weight may tilt the housing in response to proximity sensor signals or other input. Portions of the fabric may overlap light-emitting components and optical fiber configured to emit light.

Provided is a glass cloth enabling to reduce a mass of the glass cloth, being manufactured efficiently, suppressing generation of pinholes in a prepreg including the glass cloth, and maintaining excellent appearance. The glass cloth is composed of warps and wefts obtained by bundling 30 to 44 glass filaments having a diameter in the range of 3.0 to 4.0 m, the weave densities of the warp and the weft being in the range of 100 to 125 yarns/25 mm; the glass cloth has a thickness in the range of 6.5 to 11.0 m; the glass yarn coverage C is 85.5 to 99.5%; and the glass yarn coverage C, the average value F of the number of glass filaments constituting the warp and the weft, and the average value D of the weave densities of the warp and the weft satisfy the following expression (1):
53.0CF.sup.1/2/D.sup.1/257.3(1).

An item may include fabric or other materials formed from intertwined strands of material. The item may include circuitry that produces signals. The strands of material may include non-conductive strands and conductive strands. The conductive strands may carry the signals produced by the circuitry. Each conductive strand may have a strand core, a conductive coating on the strand core, and an insulating layer on the conductive coating. The strand cores may be strands formed from polymer. The conductive coating may be formed from metal. Electrical connections may be made between intertwined conductive strands by selectively removing portions of the outer insulating layer to expose the conductive cores of overlapping conductive strands. A conductive material such as solder or conductive epoxy may be applied to the exposed portions of the conductive cores to electrically and mechanically connect the overlapping conductive strands.

A luminous fiber may include a flexible printed circuit board extending in a length direction of the fiber, at least one electrically conductive trace being formed on the flexible printed circuit board, at least one light emitting component being arranged on the flexible printed circuit board and being electrically connected to the trace, and a lateral strengthening structure for strengthening the luminous fiber in lateral direction perpendicular to the length direction. The lateral strengthening structure may include two frame bars, which are formed on the flexible printed circuit board and which extend in the length direction of the fiber. The lateral strengthening structure may include several lateral support elements, which are formed on the flexible printed circuit board between the frame bars and which are coupled to the frame bars.

A fabric-based item may include a housing that is covered in fabric. Areas of the fabric may overlap input circuitry such as button switches, touch sensors, force sensors, proximity sensors, and other sensing circuitry and may overlap other components such as light-emitting components and haptic output devices. The fabric-based item may include control circuitry that gathers user input from the input circuitry and wireless communications circuitry that the control circuitry uses to transmit remote control commands and other wireless signals in response information from the input circuitry. The fabric-based item may have a weight that is located in the housing to orient the housing in a desired direction when the housing rests on a surface. A movable weight may tilt the housing in response to proximity sensor signals or other input. Portions of the fabric may overlap light-emitting components and optical fiber configured to emit light.

An interconnect component is configured as an adapter or interposer providing mechanical and electrical interconnects between conductive threads, such as those woven within fabrics, and electrical connection points, such as contact pads on a printed circuit board (PCB), a flexible printed circuit (FPC), and/or a rigid-flex circuit board.