Copper etchant compositions

An etchant for copper and copper alloys which comprises an alkaline ammoniacal copper sulfate solution and an etchant accelerating amount of a mixture comprising an ammonium halide, an alkali metal selenite and a thio compound selected from thiourea, dithiobiuret and dithiobiurea.

An etchant for copper and copper alloys in the form of an aqueous solution comprising from about 100 to about 400 g per liter of copper sulfate, ammonium hydroxide in an amount sufficient to provide a pH in the range of about 8.5 to 9.5, from about 0.5 to 5 g per liter of an ammonium halide, from about 0.001 g to 0.02 g per liter of sulfur, selenium or tellurium in the form of a water-soluble salt in which said sulfur, selenium or tellurium is present in the anion, from 0.001 g to 0.02 g per liter of an organic thio compound containing the grouping ##STR6## and from 0 to 0.2 g of a water-soluble salt of a noble metal.

An etchant for copper and copper alloys which comprises an alkaline ammoniacal copper salt solution and an etchant accelerating amount of a mixture comprising ammonium chloride, an alkali mixture comprising ammonium chloride, an alkali metal selenite, dithiobiuret and silver nitrate.

In a process for etching copper and copper alloys using an alkaline ammoniacal copper salt solution as etchant the improvement comprising incorporating into said etchant an etchant accelerating amount of a mixture comprising an ammonium halide, a water-soluble salt containing sulfur, selenium or tellurium in the anion, and an organic thio compound containing the group ##STR7##