Investigating the Effects of Stress on Die Deformation and on Cross-Axis Offset Drift in Mode-Split MEMS Gyroscopes

This letter explores intrinsic and extrinsic mechanical stress effects in mode-split, open-loop micro-electro-mechanical systems (MEMS) gyroscopes. First, the impact of stress on the deformation of a single MEMS die is experimentally investigated with white light interferometry. Only a small amount of the observed deformation of the MEMS die is found to be caused by soldering stress, whereas the main amount originates from the die attach film. In the second part of this letter, zero-rate offset drift across printed circuit board bending is investigated using MEMS gyroscope prototype devices in land grid array mold packages. While most of the offset drift can be attributed to changes of quadrature and mechanical phase error as expected, a smaller cross-axis offset contribution is demonstrated as well. Our investigation forms a further building block toward understanding root-causes of cross-axis sensitivity.