A technique for improving the tarnish and oxidation resistance of copper and copper based alloy materials is disclosed. Copper or a copper alloy is immersed in an aqueous solution containing sodium hydroxide, zinc ions and chromium (VI) ions. While the compositional ranges may vary, the concentration of either zinc ions or chromium (VI) ions, or both, is less than 1.0 gm/l. A chromium-zinc coating is electrolytically applied. The coating provides tarnish resistance at temperatures in excess of 190.degree. C. The coating is removable by immersion in sulfuric acid. Improved results are obtained by rinsing deionized water containing a small amount of an alkaline or alkaline earth hydroxide.
This application is a continuation in part of U.S. patent application Ser. No. 07/459,846 filed Jan. 2, 1990 which is a continuation in part of U.S. patent application Ser. No. 07/421,475 filed on Oct. 13, 1989.
A method for producing organic electroluminescent components having a structured electrode, in particular displays having a structured metal electrode, includes the following steps: At least two layers are applied onto a bottom electrode which is located on a substrate. The first layer is electrically insulating and is not damaged when the second layer is applied. A defined boundary remains between the two layers. The first layer has a higher solubility rate in a liquid developer than the second layer and it is possible to structure the second layer. The second layer is structured and the structure is transferred to the first layer. At least one organic functional layer is applied onto the second layer. A top electrode is deposited onto the organic functional layer.
Aqueous electroplating solutions and methods are provided for the codeposition of zinc and chromium. The solutions include effective amounts of zinc, chromium, and hydroxyl ions. The solutions further include an effective amount of one or more ions of alkali metals, alkaline earth metals, or a combination thereof other than sodium and potassium, to in major part balance the hydroxyl ions. A preferred alkali metal is rubidium.
A method for improving adhesion from a leadframe to a metallic wire is disclosed including using a laser beam to remove selected areas of an package adhesion enhancing layer to expose a layer on the leadframe which has a higher adhesion to metallic wires. The package adhesion enhancing layer is from the group consisting essentially of aluminum oxide, anti-tarnish finishes, and dielectrics. The exposed layer on the leadframe is selected from the group consisting essentially of silver, nickel, palladium.
There is provided a method of treating a copper or copper alloy substrate to provide improved resistance to both oxidation and to chemical attack. The substrate is immersed in an aqueous solution containing both chromium (VI) ion and phosphate ions. The treatment is particularly effective for protecting imaged printed circuit boards during storage, handling and use.
Providing a layer of ZnCr intermediate a dielectric substrate and a heat spreader enhances the adhesion between the dielectric substrate and heat spreader.
