The frequency adjustment method of quartz crystal unit using a quick response evaporation source

Abstract

AbstractIn the manufacture of quartz crystal units, there is a frequency adjustment process in which the individual frequencies are measured and matched to each other, resulting in a frequency adjustment method based on the use of a resistance heating evaporation source to deposit Ag, Au, and other electrode materials. The frequency measurement method used for quartz crystal units has been the oscillation method, and we proposed a transmission method based on a network analyzer and π circuit to improve measurement precision, and a standby method based on a CW sweep to increase measurement speed. We then developed a quick response evaporation source control method adapted for the proposed method. Because the CW sweep standby method sweeps only one point, measurement can be performed in a shorter time than with a linear sweep. In addition, since we were able to perform high‐precision adjustment in a short time, we implemented rate switching, starting adjustment at a high rate and finishing at a low rate, and then controlled the evaporation source so that the rate remained fixed during standby time. As a result, we were able to switch the rate in three stages for a normal frequency adjustment volume of about 1000 ppm, achieving adjustment of ±2 ppm during the deposition time of 2.5 seconds. © 2006 Wiley Periodicals, Inc. Electron Comm Jpn Pt 2, 90(1): 11–19, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecjb.20282