PURPOSE: To form a wiring pattern of a laminated thin film of Ti, Ni, Au, or the like by employing an etching liquid for forming a wiring pattern composed of a mixture of specified compounds.

CONSTITUTION: An etching solution for forming a wiring pattern is composed of a mixture of concentrated nitric acid, concentrated hydrochloric acid, hydrofluoric acid, and hydrogen peroxide water. A three-layer thin film(Ti/Ni/Au) can be etched concurrently with only one kind of such etching solution. Furthermore, width and film thickness of wiring pattern can be controlled easily. Relationship between dripping amount of hydrogen peroxide water and the wiring pattern width of laminated thin film and relationship between dripping amount of hydrogen peroxide water and the thickness of laminated thin film are shown on the drawing. Wiring pattern width and film thickness are regulated, respectively, at 50μm and 1μm. In an embodiment (represented by black and white circles), wiring pattern width and film thickness particularly close to the regulated values are obtained for the dripping amount of hydrogen peroxide water in the range of 10-20ml.