Abstract: In a glass cloth made of glass filaments having a composition which is at least 50 wt % SiO2, the filaments have a diameter that is 0.5 ?m or more and less than 3.0 ?m. The glass cloth has a thickness of 15 ?m or less and a weight of from 0.3 to 10 g/m2.

Abstract: The present invention is a resin substrate including an organic resin and a quartz glass cloth, where the organic resin has a dielectric loss tangent of 0.0002 to 0.0020 measured at 10 GHz and a 40 GHz/10 GHz ratio is 0.4 to 0.9, the quartz glass cloth has a dielectric loss tangent of 0.0001 to 0.0015 measured at 10 GHz and a 40 GHz/10 GHz ratio is 1.2 to 2.0, and the resin substrate has a dielectric loss tangent of 0.0001 to 0.0020 at 10 GHz and a 40 GHz/10 GHz ratio is 0.8 to 1.2. This provides a resin substrate having a low dielectric loss tangent in a high-frequency region and dielectric characteristics with little frequency dependence.

Abstract: The present invention is a low dielectric resin substrate, which is a composite including an annealed quartz glass cloth and an organic resin, where the annealed quartz glass cloth has a dielectric loss tangent of less than 0.0010 at 10 GHz, and tensile strength of 1.0 N/25 mm or more per cloth weight (g/m2). This provides a resin substrate that includes a quartz glass cloth which has a low dielectric loss tangent and which is also excellent in tensile strength.

Abstract: The present invention is a resin substrate including an organic resin and a quartz glass cloth, where the organic resin has a dielectric loss tangent of 0.0002 to 0.0020 measured at 10 GHz and a 40 GHz/10 GHz ratio is 0.4 to 0.9, the quartz glass cloth has a dielectric loss tangent of 0.0001 to 0.0015 measured at 10 GHz and a 40 GHz/10 GHz ratio is 1.2 to 2.0, and the resin substrate has a dielectric loss tangent of 0.0001 to 0.0020 at 10 GHz and a 40 GHz/10 GHz ratio is 0.8 to 1.2. This provides a resin substrate having a low dielectric loss tangent in a high-frequency region and dielectric characteristics with little frequency dependence.

Abstract: The present invention is a low dielectric resin substrate, which is a composite including an annealed quartz glass cloth and an organic resin, where the annealed quartz glass cloth has a dielectric loss tangent of less than 0.0010 at 10 GHz, and tensile strength of 1.0 N/25 mm or more per cloth weight (g/m2). This provides a resin substrate that includes a quartz glass cloth which has a low dielectric loss tangent and which is also excellent in tensile strength.

Abstract: The present invention is a low dielectric silica powder, which has an average particle size of 0.1 to 30 ?m and a dielectric loss tangent of 0.0005 or less at 10 GHz. An object is to provide: a silica powder with an extremely small dielectric loss tangent; a resin composition containing the same; and a method for manufacturing a silica powder with a low dielectric loss tangent and strong adhesion at the interface to resin.