| 摘要 |
PROBLEM TO BE SOLVED: To provide an etchant capable of performing single liquid or package etching without selective etching multilayered films putting Ag electrode films via a Ni ground layer on a piezoelectric substrate, and to provide an electrode forming method of a quartz crystal filter. SOLUTION: The etchant is composed of phosphoric acid, nitric acid and pure water. When the volumetric ratio of the phosphoric acid to the total volume of the etchant is defined as X(%), the volumetric ratio of the nitric acid as Y(%), and the volumetric ratio of the pure water as Z(%), the etchant is so blended as to be 41<X≤55, O<Y≤5, 43≤Z<58 (where, X+Y+Z=100). COPYRIGHT: (C)2009,JPO&INPIT
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