Epoxy resin insulating boards are hard, board-shaped insulating materials made by baking and hot pressing impregnated paper, cotton cloth, glass cloth, impregnated phenolic, and epoxy resin. These boards offer high mechanical strength, dielectric properties, oil resistance, and corrosion resistance. Epoxy resin insulating boards are suitable for use as insulating components in high-demand electrical machinery and equipment, and can be used in humid environments and transformers, with a heat resistance grade of A.