Nondestructive diagnosis of mechanical misalignments in dual axis accelerometers

Microelectromechanical systems production is still an immature technology compared to the classical semiconductor industry. MEMS fabrication and packaging processes may present misalignments which result in an improper placement of the internal microstructures or dies. In this work, the possibilities of diagnosing mechanical misalignments of dual axis IC accelerometers are explored. The used method dynamically correlates the two output signals in orthogonal directions. This leads to a Lissajous composition which is able to manifest the actual level of misalignment. The definition of a metric and its variation rate study allows the diagnosis procedure. Experimental results using a commercial dual axis capacitive accelerometer reveal diagnosis discrepancies as low as 1.1%, therefore showing the viability of the proposal.