| abstract |
The purpose of the present invention is to provide an etchant which can be used to selectively remove copper and/or a copper alloy from a substrate including copper and/or a copper alloy, and nickel and/or a nickel alloy. The etchant according to the present invention is for etching a substrate having copper and/or a copper alloy, and nickel and/or a nickel alloy, to remove the copper and/or the copper alloy, and contains an organic acid (A) and an oxidizer (B). The organic acid (A) has an acid dissociation constant (pKa) of -1.10 to 2.60. A first corrosion potential as measured using nickel as a working electrode, Ag/AgCl filled with a saturated KCl solution as a reference electrode, and the etchant as an electrolyte solution is 0.1-0.5 V. |