ETCHING SOLUTION, METHOD OF ETCHING AND PRINTED WIRING BOARD

There is provided an etching solution comprised of a cupric chloride solution and a high-concentration triazole type compound added to the cupric chloride solution and capable of forming an etching-inhibiting coating. In a process of forming a circuit pattern by etching with the etching solution, an etching-inhibiting coating is selected formed on parts of a copper foil laid under the edge of an etching resist to effectively inhibit horizontal side-etching of the copper foil from the edge of the etching resist. Also, nonuniform irregularities formed on the side wall of the circuit pattern by the etching improves the adhesion between the circuit pattern and an insulating resin layer covering the circuit pattern.