水晶振動子周波数調整後の周波数シフト

抄録

Quartz cristal units have been used widely for time and frequency contorol applications in many electoronics devices. A frequency of quartz cristal unit is adjusted by depositing a metal (silver or gold), measuring its frequency change in the proccess. For the demand of high-frequency band use and high accuracy of products recently, it has become necessary to measure frequencies by the transmission method with controlling the deposition rate in the frequency adjuster equipment. However, 4ppm frequency decrease of the cristal unit has occurred within 15 minutes after adjusting the frequency in the adjuster that vacuum had been performed by oil diffusion pumps. We found this frequency shift was the result from adsorption by oil moleculars on the fresh depositing surface, not from thermal radiation out of the evaporation source.