The Effect Of Surface Roughness Of Quartz Crystal On The Performance Of Resonators

Quartz crystal is one of the most important piezoelectric materials which is widely used in the manufacture of resonators due to its excellent mechanical,electrical,thermal characteristics and other key properties.Quartz crystal resonators have been used for high-frequency signal processing and precision timing and other critical functions,playing a vital role in the information and networking era.Engineers usually only consider the parameters such as blank size and configuration during the initial design of resonators,but with the aggressive miniaturization and increasing frequency of resonators,the influence of other smaller variables such as blank surface roughness becomes impossible to ignore.Over the past decades,the research of quartz crystal resonators have been expanded,and we have accumulated rich experiences in many aspects such as shapes,vibration modes,and production methods have also been continuously innovated.However,the effect of the surface roughness of quartz crystal blanks on the performance of resonators in the microscopic scale is not enough to satisfy the increasing requirements of precision resonators due to the strong randomness and uncertainty of the surface morphology distribution after the blank is processed.This research will establish a finite element model of a quartz crystal plate with a rough surface based on an 85 MHz,AT-cut smooth quartz crystal plate with COMSOL software and analyzes its vibration.Then designed the roughness effect experiment by controlling the grinding process,we obtained four sets of blanks with different surface quality and made resonator products with the identical process.From the measurement of these products,we obtained waveforms of blank and the electrical characteristics,DLD characteristics,temperature characteristics,and frequency deviation under long-term extreme environments of these resonators.By analyzing the experimental data,its shows that reducing the surface roughness of the blank will have a positive effect on the many properties of quartz crystal resonators such as suppressing the spurious modes,improving the quality factor,reducing the hysteresis effect and increasing the working stability in high and low temperature environments.These results provide a significant guideline for parameter optimization in the design and manufacturing of high-quality quartz crystal resonators.This is also a good start on the study of the surface roughness for the production of precision quartz crystal resonators.It will serve as a basis for further efforts on the high performance quartz crystal resonators of miniatured types.