Abstract: The invention provides a low energy loss, multi-layered polypropylene/metal foil product useful for further processing into printed circuit boards and antenna boards for microwave circuitry. A continuous process for manufacture of the product is described. The process comprises the steps of: providing metal foil; optionally, extrusion coating molten polypropylene upon said metal foil, to obtain a foil coated with a polypropylene foundation layer; casting a molten polypropylene tie-layer upon said metal foil or upon said coated metal foil; and laminating a polypropylene sheet on said tie layer. In the process, heat is applied to induce fusing of the layers of the multi-layered product.

Abstract: A method of manufacturing a low loss printed circuit board material including the steps of: providing a substrate comprising at least one layer of cross-linked polyethylene, providing a conducting foil, bringing a surface of the foil together with a surface of the substrate, casting a bonding layer of molten polyethylene between the surfaces, laminating the foil onto the substrate and cross-linking the bonding layer.