Finite element modeling of the effects of mounting stresses on the frequency temperature behavior of surface acoustic wave devices

A general finite element method has been developed for the analysis of the effects of thermally induced mounting stresses on the first order temperature behavior of SAW devices. The present study analyzes this behavior using a finite element model to obtain an accurate description of the thermal stresses and deformations in a crystal plate that has been mounted in various configurations using an adhesive to bond the quartz into a ceramic package. This solution is then combined with an analytical solution of the SAW mode shape for an arbitrary transverse harmonic in a general perturbation procedure to obtain the frequency shift. The methods developed herein are useful for studying the sensitivity of a particular mounting scheme to thermal stresses for small temperature excursions. Examples of thermal effects on SAW propagation are presented for various mounting schemes.