Insulating sheet materials, also known as dielectrics, are substances that do not conduct electricity or conduct electricity minimally under the application of direct current voltage. The primary function of insulating sheet materials is to isolate conductors at different electrical potentials in electrical equipment, allowing current to flow along a specific path. They also serve mechanical support and fixation, as well as arc extinguishing, heat dissipation, energy storage, moisture and mold prevention, and improving the potential distribution of the electric field and protecting conductors.