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: Reactor and method for removing a material such as copper from a substrate such as a printed circuit board, utilizing a liquid etchant. The work to be etched is placed in a narrow channel, and the etchant is pumped rapidly across the surface of the work at a rate such that the composition of the etchant does not change significantly from one side of the work to the other.

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.