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