Microetching and cleaning of printed wiring boards
AssigneeFMC Corporation
InventorNancy D. Arabinick
Life of this patent
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Abstract
The microetching and cleaning of copper clad substrates in printed wiring board production with solutions containing alkali metal persulfate and sulfuric acid is controlled to provide slower and more consistent copper etch rates by the presence of high proportions of alkali metal sulfate or an alkali metal sulfate/bisulfate mixture in the solutions, in a mole ratio of persulfate to sulfate or sulfate/bisulfate mixture of 1:0.1 to 1:10. When bisulfate is present with the sulfate, the sulfate will comprise at least about 10 mole % of the sulfate/bisulfate mixture. A surfactant may be present in the solutions to aid wettability on the copper clad substrates.
Claims40
A composition for microetching and cleaning copper clad substrates in the production of printed wiring boards, the composition comprising a dry mixture of (a) an alkali metal persulfate and (b) a metal salt component selected from the group consisting of alkali metal sulfates and mixtures of alkali metal sulfates and alkali metal bisulfates, wherein the mole ratio of (a) to (b) is in the range of 1:0.1 to 1:10, and an alkali metal sulfate comprises at least about 10 mole % of metal salt component (b).
The composition of any of claims 1-6 and 29-32 wherein the alkali metal of (a) and (b) is sodium, potassium or a combination thereof.
The composition of any of claims 1-6 and 29-32 wherein the alkali metal of (a) and (b) is sodium.
A microetchant and cleaning solution for copper clad substrates in the production of printed wiring boards, said solution comprising, dissolved in an aqueous medium in concentrations effective for microetching and cleaning action, (a) an alkali metal persulfate, (b) a metal salt component selected from the group consisting of alkali metal sulfates and mixtures of alkali metal sulfates and alkali metal bisulfates, and (d) sulfuric acid, wherein the a:b:d mole ratio is in the range of 1:0.3:0.2 to 1:10:3 and the amount of alkali metal sulfate in the mixture of (b) is at least 10 mole %.
A microetchant and cleaning solution for copper clad substrates in the production of printed wiring boards, said solution consisting essentially of, dissolved in an aqueous medium in concentrations effective for microetching and cleaning action:
- (a) an alkali metal persulfate:
- (b) a metal salt component selected from the group consisting of alkali metal sulfates and mixtures of alkali metal sulfates and alkali metal bisulfates, said mixtures containing at least 10 mole % alkali metal sulfate;
- optionally a water soluble metal salt different from metal salt component (b), said component (c) selected from the group consisting of metal sulfates, metal bisulfates, and mixtures thereof, wherein the mole ratio of (a) to (c) is in the range of 1.0:0.001 to 1:1;
- (d) sulfuric acid;
- and
- optionally a surfactant (e) in an amount effective to improve wettability of the solution on the copper clad substrate;
- wherein the a:b:d mole ratio is in the range of 1:0.3:0.2 to 1:10:3.
Dependencies are inferred from the claim text.