Abstract: An aqueous solution for surface treatment, for treating a surface of an alloy, the aqueous solution comprising: a copper compound at a copper ion concentration of 20000 ppm or more and 50000 ppm or less; a heterocyclic nitrogen compound at a concentration of 200 ppm or more and 3000 ppm or less; and a halide ion at a concentration of 2000 ppm or more and 70000 ppm or less.

Abstract: An etchant capable of selectively etching copper and a copper alloy while suppressing dissolution of nickel, tin, gold, and an alloy thereof. The etchant contains: (A) 5-10.5% by mass of hydrogen peroxide with respect to the total mass of the etchant; (B) 0.3-6% by mass of nitric acid with respect to the total mass of the etchant; (C) at least one nitrogen-containing 5-membered ring compound selected from triazoles and tetrazoles, which may have at least one substituent selected from a C1-6 alkyl group, an amino group, and a substituted amino group having a substituent selected from a C1-6 alkyl group and a phenyl group; and (D) (d1) one or more pH adjusters selected from an alkali metal hydroxide, ammonia, an amine, and an ammonium salt, (d2) a phosphoric acid compound, or (d3) a combination of (d1) and (d2).

Abstract: The present invention relates to an etchant capable of selectively etching copper and a copper alloy while suppressing dissolution of nickel, tin, gold, and an alloy thereof. This etchant is characterized by comprising: (A) 5-10.5% by mass of hydrogen peroxide with respect to the total mass of the etchant; (B) 0.3-6% by mass of nitric acid with respect to the total mass of the etchant; (C) at least one nitrogen-containing 5-membered ring compound selected from the group consisting of triazoles and tetrazoles, which may have at least one substituent selected from the group consisting of a C1-6 alkyl group, an amino group, and a substituted amino group having a substituent selected from the group consisting of a C1-6 alkyl group and a phenyl group; and (D) (d1) one or more pH adjusters selected from the group consisting of an alkali metal hydroxide, ammonia, an amine, and an ammonium salt, (d2) a phosphonic acid compound, or (d3) a combination of (d1) and (d2).