Resin substrate, metal foil laminate, and wiring board

Abstract

This invention relates to a resin substrate comprising a glass cloth woven from glass yarn with a Si content (converted to SiO2) ranging from 95% to 100% by mass, and a resin composition. The glass cloth, calculated by the formula: yarn width variation coefficient = yarn width standard deviation [μm] / yarn width [μm], has a value of less than 0.20 in both the warp and weft directions, and a loss tangent (tanδ) of less than 0.34 at 200°C.