Patent ID: 8357307

Claim:
A method of forming an electronic circuit by etching a copper-clad laminate, wherein a nickel or nickel alloy layer with a low etching rate is formed on an etching side of a copper layer formed of a rolled copper foil or an electrolytic copper foil, a surface of a non-etched side of the copper layer is thereafter bonded to a resin substrate to obtain a copper-clad laminate, a resist pattern for forming a circuit is subsequently applied on the side with the copper layer and the nickel or nickel alloy layer, any unwanted portion of the copper layer and the nickel or nickel alloy layer of the copper-clad laminate other than a portion to which the resist pattern was applied is removed using an etching solution of an aqueous ferric chloride, the resist is further removed, and soft etching is additionally performed in order to remove the remnant nickel or nickel alloy layer and thereby form a circuit.