Stock material or miscellaneous articles – All metal or with adjacent metals – Foil or filament smaller than 6 mils
Reexamination Certificate
1999-08-18
2002-04-16
Jones, Deborah (Department: 1775)
Stock material or miscellaneous articles
All metal or with adjacent metals
Foil or filament smaller than 6 mils
C118S301000, C118S406000, C156S345420, C427S099300, C427S124000, C427S255250, C427S256000, C428S624000, C428S628000, C428S629000, C428S632000, C428S636000, C428S637000, C428S640000, C428S646000, C428S647000, C428S648000, C428S651000, C428S652000, C428S656000, C428S658000, C428S665000, C428S669000, C428S670000, C428S671000, C428S672000, C428S673000, C428S674000, C428S675000, C428S680000, C428S687000, C428S901000, C428S924000, C428S926000, C428S938000
Reexamination Certificate
active
06372364
ABSTRACT:
The present invention involves a nanostructure, coating surface for improved adhesion to materials. More specifically, the invention is a laminate product produced by applying a coating having a roughened surface onto a substrate, and the method of producing this product.
BACKGROUND OF THE INVENTION
In the thin film industry, it is often desirable to have a thin film attached or coated onto a thicker, substrate of the same or different material. To increase adhesion to the substrate, the surface of the thin film contacting the substrate may be roughened by etching or other processes. These processes are difficult to control and can reduce the integrity of the thin film itself, unless the film is relatively thick. In addition, the etching processes involved use environmentally unsafe, waste materials that must be cleaned, recycled and/or disposed of. One such application of thin films involves producing a copper thin film by deposition copper onto a first temporary substrate, and then transferring the thin film onto a final substrate for the production of integrated circuits, printed circuit boards and other electronic applications. In order to apply the thin film to the final product, the thin film must be capable of being easily peeled away from the temporary substrate, and at the same time must adhere to the temporary substrate well enough to remain in place during handling. The temporary substrate (often aluminum or copper) is then peeled off of the copper thin film, leaving the thin film of copper on the final substrate. While there are prior art methods of forming these thin films on temporary substrates, some of these methods require a vacuum environment, which prohibits the use of some materials and makes cooling of the substrate difficult. The present invention overcomes these disadvantages and others by using combustion chemical vapor deposition CCVD or concentrated heat deposition CHD to directly coat the thin film onto the temporary substrate. This results in a thin film that is firmly supported by a substrate for handling purposes, yet easily peeled from this substrate for use. In addition, the product produced using the disclosed methods produces a roughened exposed surface having nanostructure features that interact with the final substrate, thereby producing a stronger adhesion between the thin film and the final permanent substrate and product, while providing a desired thin continuous layer.
U.S. Pat. No. 3,969,199, issued on Jul. 13, 1976 to Berdan et al., discloses a method of coating aluminum with a strippable copper deposit. This method involves pre-treating the aluminum carrier with an alkaline, aqueous, alkali metal zincate solution containing a minor amount of water-soluble salt. The salt is selected from iron, cobalt and nickel. This temporary coating is then removed using acid. By pre-treating the aluminum carrier in this manner, the initial copper electroplated to the aluminum consists of a very high density of small copper nuclei. This results in peel strengths not greater than 2 lbs. per inch width. While the pretreating methods disclosed in this patent may be useful with the present invention, there is no discussion concerning the roughening of the exposed copper surface.
Metal-clad laminates are the subject of U.S. Pat. No. 3,984,598, issued on Oct. 5, 1976 to Sarazin et al. These laminates comprise a metal coating about 1 to 20 microns thick that is deposited on a substrate, after treating the substrate with a release agent. One example given is coating stainless steel with a copper coating after treating the stainless steel with a silane release agent. The upper side of the copper is treated by passing a high currant density and oxidizing the surface using heat. The oxidized surface is treated with a silane bonding agent and is then bonded to a glass epoxy resin laminate. The stainless steel is then removed. While a high degree of adhesion between the copper coating and the glass epoxy resin laminate is achieved using this method, a number of steps are involved, resulting in a costly process. In contradistinction, the present invention roughens the exposed copper (or other material) surface during the coating operation, thus reducing costs as well as the effect on the environment. Furthermore, the larger features associated with the oxidized surface of the copper reduces the overall conductivity per unit weight of the copper, as opposed to the product of the present invention that simply roughens a pure copper surface with smaller features, enabling thinner films, thereby requiring less copper and thus faster etching times
In U.S. Pat. No. 4,357,395, issued on Nov. 2, 1982., U.S. Pat. No. 4,383,003, issued on May 10, 1983 and U.S. Pat. No. 4,431,710, issued on Feb. 14, 1984, all to Lifshin et al., a number of transfer lamination methods and products are disclosed. The most pertinent of these methods and products is illustrated in FIG. 6 of the '395 Patent. An aluminum carrier sheet is first treated with a release agent (such as silicone dioxide, silicon oxide or soda-lime window glass). A copper coating is then applied by sputtering or other coating technique resulting in a thin film (up to 25 microns) copper layer having a relatively small grain size. The exposed surface of the copper coating is then treated electrolytically or by other methods to alter the morphology of the copper surface. This increases the mechanical interlocking of the copper when bonded to another surface. One such method involves treating the copper surface in a baths of progressively weaker concentrations of copper sulfate. The details (grain or relief sizes) of the roughened copper surface are not disclosed, however, peel strengths on the order of 8 pounds per inch are achieved. As with other known methods, the methods discussed in these patents involve many steps to produce the final product. In addition, while the final product does include a roughened copper surface, the features of the surface are non-uniform and larger when compared to the nanostructure surface of the present invention. This can result in areas having greater adhesion than other areas, as well as areas with varying current carrying capabilities. By providing a surface with nanostructure features, the present invention provides uniform adhesion across the entire surface using a minimum of additional copper or other coating material.
U.S. Pat. No. 5,057,372, issued on Oct. 15, 1991 to Imfeld et al., is directed to a multi-layer film and laminate for use in producing printed circuit boards. The multi-layer film acts as a protective carrier sheet for a metal foil such as copper. An adhesive layer is provided on the surface of the carrier sheet. The adhesive layer is heated or softened to create a releasable bond between the copper foil and the carrier sheet. After the film/foil laminate is placed in a heated press for lamination or molding to the prepreg, the carrier sheet is easily removed. Peel test between the film and foil are between 0.4 pounds/in-width and 0.005 pounds/in-width and preferably between 0.1 pounds/in-width and 0.01 pounds/in-width. This patent is directed mainly to the interface between the film and the foil, and therefore, details concerning the exposed copper surface, or the copper foil production method used, are not disclosed.
An easily peelable or chemically strippable laminate is described in U.S. Pat. No. 5,332,975, issued on Jun. 21, 1994 to Nagy et al. The laminate includes an aluminum layer with an aluminum oxide layer. A thin layer of copper foil is then electroplated on the aluminum oxide, and a thin layer of brass is electroplated on the copper. This results in a copper deposit, which exhibits a low porosity, while the brass layer provides a thermal barrier between the polymeric substrate and the copper foil. The aluminum oxide layer acts as a release agent for the aluminum carrier. The peel strength between the copper and aluminum layers is dependent on the thickness of the aluminum oxide layer and preferably ranges between 0.1 and 0.5 lb./in. While the brass la
Hunt Andrew T.
Luten, III Henry A.
Jones Deborah
Koehler Robert R.
MicroCoating Technologies, Inc.
Muratori Alfred H.
Nacker Wayne E.
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