Abstract: An etchant of the present invention includes an aqueous solution containing hydrochloric acid, nitric acid, and a cupric ion source. An etching method of the present invention includes bringing the etchant into contact with at least one metal selected from nickel, chromium, nickel-chromium alloys, and palladium. Another etching method of the present invention includes bringing a first etchant that includes an aqueous solution containing at least the following components A to C (A. hydrochloric acid; B. at least one compound selected from the following (a) to (c): (a) compounds with 7 or less carbon atoms, containing a sulfur atom(s) and at least one group selected from an amino group, an imino group, a carboxyl group, a carbonyl group, and a hydroxyl group; (b) thiazole; and (c) thiazole compounds; and C.

Abstract: An etchant of the present invention includes an aqueous solution containing hydrochloric acid, nitric acid, and a cupric ion source. An etching method of the present invention includes bringing the etchant into contact with at least one metal selected from nickel, chromium, nickel-chromium alloys, and palladium. Another etching method of the present invention includes bringing a first etchant that includes an aqueous solution containing at least the following components A to C (A. hydrochloric acid; B. at least one compound selected from the following (a) to (c): (a) compounds with 7 or less carbon atoms, containing a sulfur atom(s) and at least one group selected from an amino group, an imino group, a carboxyl group, a carbonyl group, and a hydroxyl group; (b) thiazole; and (c) thiazole compounds; and C.

Abstract: An etchant of the present invention includes an aqueous solution containing hydrochloric acid, nitric acid, and a cupric ion source. An etching method of the present invention includes bringing the etchant into contact with at least one metal selected from nickel, chromium, nickel-chromium alloys, and palladium. Another etching method of the present invention includes bringing a first etchant that includes an aqueous solution containing at least the following components A to C (A. hydrochloric acid; B. at least one compound selected from the following (a) to (c): (a) compounds with 7 or less carbon atoms, containing a sulfur atom(s) and at least one group selected from an amino group, an imino group, a carboxyl group, a carbonyl group, and a hydroxyl group; (b) thiazole; and (c) thiazole compounds; and C.

Abstract: An etchant for copper or copper alloys comprising 5-50 wt % of an alkanolamine, a copper ion source in the amount of 0.2-10 wt % as copper, a halide ion source in the amount of 0.005-10 wt % as halogen, 0.1-30 wt % of an aliphatic carboxylic acid, and the balance water, wherein the molar ratio of the alkanolamine to one mol of the aliphatic carboxylic acid is two or more. The etchant is free from problems such as instability of the liquid composition and unpleasant odor, has a high etching rate, exhibits only very slight corrosion even if a small amount of residue is left on the surface and is capable of producing a roughened surface when used for microetching.