Importance

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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.

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First Claim