Ammoniated etching solution and process for its regeneration utilizing ammonium chloride addition

摘要

The addition of a small quantity of ammonium chloride to an ammonium sulfate etching solution results in shortening the regeneration time of the spent etching solution when air or oxygen is bubbled through it to reoxidize it, and it also results in accelerating the etching rate. The extent of this improvement deteriorates with increasing chlorine ion content, disappearing when the chlorine ion content substantially exceeds 0.4% by weight of the solution and still greater chlorine ion additions are distinctly undesirable. The electrolysis of the etching solution to remove etched-away metal cathodically produces enough oxygen at the anode to prevent any substantial evolution of chlorine from the electrolytic action on the small chlorine ion content.