The reduction of microphonics in crystal resonators

It is experimentally demonstrated that microphonics in VHF quartz resonators due to spurious flexural modes can be reduced substantially through a special support configuration that utilizes a viscoelastic adhesive cushion, which secures the resonator plate to the support posts. Resonators previously have been supported via a hard-drying epoxy formulation yielded a rigid coupling system between resonator and support posts. A number of SC-cut quartz resonators, both with the soft-supported mount and with a rigid epoxy support, were examined in an experimental study. Both were subjected to a high-level acoustic-noise spectrum up to about 20 kHz. The study included a large number of nearly identical resonators of both types and showed that the soft cushion is an effective means of reducing the spurious responses