What is the function of the barrier material on the bottom platen of a RF (Radio Frequency) welding machine and is it necessary?

TWI Frequently asked questions

Materials such as elephantide, polyester film or phenolic laminates, which have high dielectric properties are often used to line the base platen. These barrier, or buffer, materials thermally insulate the weld area, allowing a greater area of weld to be made for a given amount of RF power. They also prevent the edge of a tear-seal electrode touching the bottom platen and producing an arc.