Abstract: A method of etching copper and copper alloys by means of an ammoniacal etching solution containing chloride ions and for regenerating this etching solution during this etching process by adding an ammoniacal compound, for example, in the form of ammonium hydroxide or ammonia gas, as well as hydrochloric acid and water to the etching solution in accordance with continuous measurements of the pH-value and the specific gravity of the etching solution.

Abstract: A workpiece is passed through an etching tank, and then through at least an upstream rinsing tank and a downstream rinsing tank. In each of the tanks a respective liquid is pumped up from a sump at the bottom and sprayed over the workpiece as it passes through. Liquid is drawn out of the upstream rinse tank and mixed with regenerator chemicals to replenish liquid lost by the etcher and maintain the liquid in the etcher at full strength. Liquid lost from the upstream rinser in this manner is replenished by introduction into the downstream rinser of fresh water and passage of liquid from the downstream rinser to the upstream rinser through an overflow that maintains a higher liquid level in the downstream rinser than in the upstream rinser.

Abstract: A method of etching copper and copper alloys by means of an ammoniacal etching solution containing chloride ions and for regenerating this etching solution during this etching process by adding an ammoniacal compound, for example, in the form of ammonium hydroxide or ammonia gas, as well as hydrochloric acid and water to the etching solution in accordance with continuous measurements of the pH-value and the specific gravity of the etching solution.