Abstract: Disclosed is a printed wiring board which attains aims of printed wiring boards required for realizing high-speed, high-frequency semiconductor devices, namely a printed wiring board having low dielectric constant, low dielectric loss tangent and low linear expansion coefficient. Also disclosed is a composite woven fabric suitably used as a base material for such a printed wiring board. Specifically disclosed is a composite woven fabric containing quartz glass fibers and polyolefin fibers, in which the ratio of the quartz glass fibers to the composite woven fabric is set at 10 vol % or more and 90 vol % or less. It is preferred that the quartz glass fibers each have a filament diameter of 3 ?m or more and 16 ?m or less, and the composite woven fabric has a thickness of 200 ?m or less.

Abstract: A member for a plasma etching device, comprising a coating film of yttrium oxide or YAG having a coating film thickness of 10 ?m or more, a coating film thickness variance of 15% or less, preferably a surface roughness (Ra) of 1 ?m or less, formed on a surface of a member, comprising quartz glass which contains 1 to 10% by weight of yttrium oxide or YAG. The member for a plasma etching device has high plasma resistance, is not subjected to an abnormal etching on the basis of a partial change of electric properties and, accordingly, can be used for a long period of time. Even when the member is large enough to handle 12-inch Si wafers, the above-described advantageous properties are maintained and the member can be used for a long period of time.

Abstract: An object of the present invention is to provide an improved blank such that an optical member of a high homogeneity can be obtained therefrom, and to provide a vessel and a heat treatment method for heat-treating a highly uniform synthetic quartz blank. In a first aspect of the invention a special designed blank is provided showing a concave shaped outer surface. In a second aspect of the invention a special designed vessel for heat-treating blanks is provided, whereby the degree of heat emission at the center is set higher than that of the surroundings.

Abstract: In a quartz glass crucible obtained by heating and fusing a rotating layer (3) charged with a powder of silicon dioxide, impurity elements are controlled so that copper, chromium, and nickel each amount to 0.5 ppb or less, iron amounts to 120 ppb or less, and sodium amounts to 20 ppb or less. The silicon dioxide powder is supplied to a rotatable mold (1) having an open top, thereby forming a layer (3) charged with silicon dioxide along the inner peripheral wall of the mold. The layer (3) is internally heated and fused while covering the open top with a lid (5) having two or more holes (6,7), and the mold (1) is ventilated to discharge the high temperature gases through the holes (6,7).