Design, Test, and Evaluation of a Novel Die-Attach Structure for Packaging Stress Suppression of MEMS Resonant Accelerometers

An effective suppression of packaging stress is significant for MEMS-based inertial sensors in the application of high-performance navigation systems. This article proposes a novel glass gasket with an aim to cushion the die-attach thermal stress and thus improve the temperature stability of MEMS resonant accelerometers (MRAs). Both the gasket with five dedicated bosses and an auxiliary die-attach fixture (ADF) are presented to prevent adhesive overflow and ensure die-attach consistency. Three test methods are utilized to evaluate the suppression effect of packaging stress by a direct measurement and comparison of before and after die attach. The measured die warpage, resonant frequency change, and temperature drift coefficient (TDC) of resonators are presented to describe the relationship between packaging stress and frequency drift of MRAs. The experiment results show that the minimum TDC induced by the die-attach process has been reduced down to 0.0021 Hz/°C. The Allan variance results also demonstrate that the MRAs optimized with this die-attach process exhibit the improved comprehensive performance. These evaluation methods offer a solution for quantification of packaging stress effect in various MEMS resonant sensors.