Abstract: The present invention is directed to an improved method of making a thin copper foil preferably about 0.5 oz. per sq. ft. or less in weight, and carrier composite by forming, as by electroplating, the thin foil on a metallic surface such as a plating belt, then contacting the exposed side of the thin foil, while it is still on that metallic surface, with fusible solid plastic particles, depositing such particles on that exposed side of the foil and coalescing them together by sufficient heat to form them into a unitary plastic sheet, but insufficient to permit the plastic to migrate through any openings in the foil onto the metallic surface. The thus formed copper foil plastic carrier sheet composite is then readily removed from the metallic surface without any damage to the foil and without plastic build-up on the metallic plating surface. The method therefore can be operated efficiently continuously over long periods of time to produce a high quality composite product suitable for a variety of uses.

Abstract: The improved method of the invention comprises disposing a chromium oxide release layer on the surface of a thin inexpensive metal carrier, such as foil, depositing copper on the release layer to form a thin copper foil, and readily peeling the thus-formed copper foil from the release layer on the carrier. The release layer can be formed in situ from chromium metal electroplated on the carrier. The freshly prepared release layer contains numerous small sites on which electroplating of the copper can be easily carried out to produce pore-free copper foil. The method, which employs the carrier-release layer composite of the invention, is inexpensive and efficient, since readily available, inexpensive metal carriers can be used and no complicated copper foil-carrier separation steps need be resorted to. Moreover, it can increase the bondability of the thin copper foil thus produced to plastic during lamination thereof.

Abstract: The improved method of the invention includes depositing, as by electroplating, a coating of porefree copper on a clean fresh plateable layer, such as selected metal oxide, on a surface of a flexible elongated metal strip or belt to form copper foil, stripping the foil from the layer, removing the layer from the belt and reforming it, as by electro-deposition or the like, as a fresh clean layer ready to receive a copper coating as above. The steps of the method are performed in separate treating zones and the method can be continuous.At least certain of the major treating zones preferably are in duplicate so as to facilitate maintenance thereof without interrupting the continuous production of the copper foil. In one embodiment the copper foil, before it is stripped from the plateable layer, is treated to increase its bondability to plastics.

Abstract: The improved plastic-metal unitary composite of the invention formed by the present method, includes (a) a thin copper foil, for example, weighing about 1 or 2 ounces per square foot, one side of which has a rough irregular surface with improved bondability to plastic but increased propensity for staining, (b) a thin layer of metal selected from Cr, Al, Cd or a Cd alloy of Sn, Zn or Cu, or a mixture thereof, encapsulating the rough surface so as to decrease its staining characteristic without substantially descreasing its bondability, and (c) a plastic substrate bonded to the encapsulating layer. The rough irregular surface of the foil includes a plurality of discrete particles of copper and/or copper oxide adherent to the copper foil but detachable therefrom and embeddable in the plastic.