At-cut crystal oscillating reed and method of etching the same

Year	Description
1992	Invention patented by Hideaki Nakamura and Eiji Karaki on March 29th, 1992. Abstract: An AT-cut crystal oscillating reed formed by etching an AT-cut crystal wafer is provided. The wafer has a rotational parallel cut obtained by rotating a parallel cut by an angular degree of .theta..degree. relative to the X-axis of the wafer. The etching cross-section of the AT-cut crystal oscillating reed has a surface at an angle about 90.degree. from the front or back surface of the AT-cut crystal oscillating reed. This AT-cut crystal oscillating reed exhibits uniform characteristics and excellent reliability. Also provided is an AT-cut crystal oscillating reed with a low CI value. Finally, a method of etching an AT-cut crystal oscillating reed from an AT-cut crystal wafer is provided. A corrosion resisting film with gaps coats the wafer and is used in the etching process. In a preferred embodiment, the thickness of the wafer is designated t, the width of the gaps in the corrosion resisting films is designated l, and l.gtoreq.t/tan .theta.. The corrosion resisting film may be metal and may be formed into electrodes after the crystal oscillating reed is etched. In this manner, crystal oscillating reeds may be mass produced at a relatively low cost.
Source: selected by the editor from original sources.

Invention: At-cut crystal oscillating reed and method of etching the same