An Analytical Model to Predict Extrinsic Aging in BAW Resonators

This manuscript introduces a 1D analytical model to predict the Bulk Acoustic Wave (BAW) resonator aging when it is due to package stress relaxation. Classical micro-acoustic resonator aging models rely on a logarithmic function to estimate the 10-year instability. However, this function is fitted through experiments and does not take into account the physical stress phenomenon. Instead, our proposed analytical model computes the frequency drift by relating the thermally-induced stress in BAW to the creep response of attached epoxy. To validate the model, we design an experiment in which a type of BAW resonator known as DBAR is attached to a single epoxy layer and subjected to different baking conditions.