Composition and method for etching copper substrates
AssigneePhilip A. Hunt Chemical Corporation
InventorDonald J. Sykes
Life of this patent
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Abstract
An alkaline copper etching working bath for dissolving copper containing an etch accelerating additive selected from the group consisting of cyanamide and its precursors. The accelerating additives when added to the alkaline copper etching bath increase the etch rate and reduce undercut. The bath includes cupric ions, an ammonium salt such as a chloride and/or a carbonate, ammonium hydroxide to achieve a pH greater than 7, water, and the etch accelerating additive. The invention includes etching baths, methods for their use, the preparation of a certain etch accelerating additive and the provision of certain cyanamide precursors.
Claims28
An aqueous alkaline ammoniacal cupric etching spray bath containing an etch accelerating additive selected from the group consisting of cyanamide and its precursors, said etch accelerating additive being present in an amount sufficient to increase the etch rate of said bath by at least about 10 percent over an identical aqueous alkaline copper etching bath free of said additive.
A process of etching a copper-clad substrate having a portion of its surface masked with a resistant coating including the step of forcefully contacting both the masked and unmasked portions of said surface with a stream of an aqueous alkaline ammoniacal cupric etching solution containing an etch-accelerating-additive selected from the group consisting of cyanamide and its precursors, said etch-accelerating additive being present in an amount sufficient to increase the etch-rate of said bath by at least about 10 percent over an identical aqueous alkaline copper etching bath free of said additive and without substantially increasing the amount of undercut over the undercut obtained on a copper-clad substrate with an identical aqueous alkaline etching-bath free of said additive.
An aqueous alkaline ammoniacal cupric etching bath containing an etch accelerating additive which is selected from the group consisting of thiourea and reaction products of thiourea with cupric salts in an alkaline medium, said etch accelerating additive being present in an amount sufficient to increase the etch rate of said bath by at least about 10 percent over an identical aqueous cupric etching bath free of said additive.
A process of etching a copper-clad substrate having a portion of its surface masked with a resistant coating including the step of forcefully contacting both the masked and unmasked portions of said surface with a stream of an aqueous ammoniacal cupric etching solution containing an etch accelerating additive which is selected from the group consisting of thiourea and reaction products of thiourea with cupric salts in an alkaline medium, said etch accelerating additive being present in an amount sufficient to increase the etch rate of said bath by at least about 10 percent over an identical aqueous alkaline cupric etching bath free of said additive and without substantially increasing the amount of undercut over the undercut obtained on a copper-clad substrate with an identical aqueous alkaline cupric etching bath free of said additive.
Dependencies are inferred from the claim text.