Abstract: Copper etching process and product in which a material which promotes the formation of nitrous acid is included in the copper. The copper is etched in a nitric acid solution, and the nitrous acid catalyzes the reaction between the nitric acid and the copper. The catalyst promoter is distributed within the copper to control where the nitrous acid is formed and, hence, the manner in which the copper is etched. In one disclosed embodiment, the material which promotes the formation of nitrous acid increases in concentration toward the substrate, or board to which the copper is bonded. The nitrous acid reacts vigorously with the copper, and the etch rate increases as the etch progresses through the copper toward the substrate. A polymer and/or a nitrous acid scavenger can be included in the etching solution to confine the etching reaction to the region in which the nitrous acid is formed.

Abstract: Vertical spray etch reactor and method in which a nitric acid etching solution is sprayed onto an upright workpiece in the form of low impact, large drops to produce a gentle sheeting flow of the etching solution down the workpiece. The solution is sprayed in a generally trapezoidal pattern with the greater portion of solution being sprayed onto the upper portion of the workpiece. The etching solution is delivered to the spray nozzles by a low shear positive displacement pump. As the workpiece leaves the etch chamber, it is sprayed with a solution to remove the etching solution and dissolved copper and to adsorb gaseous by-products from the etching reaction. The rinsing solution is collected and utilized to replenish the etching solution. The workpiece receives additional rinsing in a third chamber, and gases are exhausted from the system through an exhaust vent in the third chamber. Air is introduced into the etch chamber to move the gaseous by-products toward the exhaust vent.

Abstract: Copper etching process and product in which a material which promotes the formation of nitrous acid is included in the copper. The copper is etched in a nitric acid solution, and the nitrous acid catalyzes the reaction between the nitric acid and the copper. The catalyst promoter is distributed within the copper to control where the nitrous acid is formed and, hence, the manner in which the copper is etched. In one disclosed embodiment, the material which promotes the formation of nitrous acid increases in concentration toward the substrate, or board to which the copper is bonded. The nitrous acid reacts vigorously with the copper, and the etch rate increases as the etch progresses through the copper toward the substrate. A polymer and/or a nitrous acid scavenger can be included in the etching solution to confine the etching reaction to the region in which the nitrous acid is formed.

Abstract: Copper etching process and product particularly suitable for use in the manufacture of printed circuit boards. The copper is etched in a liquid etchant, and the crystal structure of the copper is selected and carefully controlled to provide an anisotropic etch and a relatively high vertical-to-lateral etching ratio. In one disclosed embodiment, the etching solution contains nitric acid, copper nitrate or sulfuric acid, a polymer and a surfactant, and the copper has a top surface crystal structure with predominantly (111) to (200) orientations and relatively little (220) orientation. In another disclosed embodiment, the etching solution contains hydrogen peroxide and sulfuric acid, and the copper foil has a top surface crystal structure with predominantly (311) and (511) orientations and/or (111) and (200) orientations.

Abstract: Copper etching process and product particularly suitable for use in the manufacture of printed circuit boards. The copper is etched in a liquid etchant, and the crystal structure of the copper is selected and carefully controlled to provide an anisotropic etch and a vertical-to-lateral etching ratio greater than 1:1. In one disclosed embodiment, the etching solution contains nitric acid, copper nitrate or sulfuric acid, a polymer and a surfactant, and the copper has a top surface crystal structure with predominantly (111) orientation. In another disclosed embodiment, the etching solution contains hydrogen peroxide and sulfuric acid, and the copper foil has a top surface crystal structure with predominantly (311) and (511) orientations and/or (111) orientation.

Abstract: Copper etching process and product particularly suitable for use in the manufacture of printed circuit boards. The copper is etched in a liquid etchant, and the crystal structure of the copper is selected and carefully controlled to provide an anisotropic etch and a relatively high vertical-to-lateral etching ratio. In one disclosed embodiment, the etching solution contains nitric acid, copper nitrate or sulfuric acid, a polymer and a surfactant, and the copper has a top surface crystal structure with predominantly (111) and (200) orientations and relatively little (220) orientation. In another disclosed embodiment, the etching solution contains hydrogen peroxide and sulfuric acid, and the copper foil has a top surface crystal structure with predominantly (311) and (511) orientations.

Abstract: Process and solution for etching copper, for example, to remove it from printed circuit boards. The etching is effected by an aqueous solution of nitric acid, a polymer which inhibits undercutting of the copper, a surfactant, and sulfuric acid and/or an alkane sulfonic acid such as methane sulfonic acid.

Abstract: Process and solution for etching nickel and nickel alloys, particularly suitable for use in the manufacture of printed circuit boards. The nickel or alloy is contacted with an aqueous solution of nitric acid, nickel nitrate, a halogen additive and a surfactant. In some embodiments, a small amount of an amino acid is included in the solution to enhance the smoothness of the edges of the etched patterns.

Abstract: Process and solution for etching copper and other metals, wherein the etching solution is regenerated and the copper or other metal is recovered in a relatively pure and useful form. The metal is contacted with an aqueous solution of nitric acid to dissolve the metal and form a nitrate of the metal, and sulfuric acid is added to the solution to convert the nitrate to nitric acid and a precipitate of the metal.

Abstract: Process and apparatus for anisotropically etching copper through a nickel-gold mask on a circuit board. An electrical connection is made between the copper and the reactor wall or another electrical conductor contacted by the etching solution. The copper is removed anisotropically, without undercutting or lateral etching of the copper beneath the nickel-gold mask.

Abstract: Nitrogen dioxide process for etching copper and other metals, using water as a catalyst/solvent. In one disclosed embodiment, a film of water is formed on the surface of the metal, and the water-covered metal is exposed to gaseous NO.sub.2 to dissolve the metal. In another embodiment, the metal is exposed to an aqueous solution of NO.sub.2 or HNO.sub.3 in water, either by immersion or by spraying, to remove the metal.

Abstract: Plasma etching process for etching aluminum-copper alloys. The aluminum is reacted with a reactive chlorine specie, and the copper is oxidized by a nitrogen compound to form a CuCl.sub.2.Al.sub.2 Cl.sub.6 complex by which the copper is readily removed.

Abstract: Process and structure for etching copper, as in the manufacture of printed circuit boards. The copper is exposed to a gaseous or liquid oxidant in the presence of a catalyst which promotes the reaction of copper with the oxidant. In some embodiments, the catalyst is carried by a medium which also serves as a receiver for oxidized copper species produced by the reaction, and in one preferred embodiment, the medium comprises a laminated structure having a first layer which contains a catalyst and a second layer which receives the oxidized copper species. The etching is substantially anisotropic, which alleviates the problem of undercutting.

Abstract: Process and structure for etching copper, as in the manufacture of printed circuit boards. The copper is exposed to a gaseous or liquid oxidant in the presence of a catalyst which promotes the reaction of copper with the oxidant. In some embodiments, the catalyst is carried by a medium which also serves as a receiver for oxidized copper species produced by the reaction, and in one preferred embodiment, the medium comprises a laminated structure having a first layer which contains a catalyst and a second layer which receives the oxidized copper species. The etching is substantially anisotropic, which alleviates the problem of undercutting.

Abstract: An alkali flame ionization detector having an independently biased activator intermediate the flame tip member and the ion collector has been found to yield ion current collector signals which will be selectively positive-going, negative-going or null in response to selected ionic species at an appropriately chosen value of bias potential. Elemental specificity has been found for those values of bias potential which produce a null signal in the presence of a sample.

Abstract: A dense film of silicon nitride is deposited by a plasma discharge in a vapor of azidotrimethylsilane (AZS) (CH.sub.3).sub.3 SiN.sub.3. AZS is less reactive and easier to handle than the previously used silane SiH.sub.4. The resulting film is more stable chemically than the silicon nitride produced by other processes. It is useful for protective and anti-reflective coatings, for insulating, and for masking, particularly on semiconductive devices.