Long-term Stability of Alignment of Biaxial Microelectromechanical System Accelerometers

The long-term stability of alignment precision of microelectromechanical system accelerometers was evaluated. Four commercial biaxial accelerometers (two ADXL 202E and two ADXL 203 accelerometers by Analog Devices Inc.) were tested over a period of 20 and 15 years, respectively. The experimental studies were performed using a custom computer-controlled test rig and employing gravitational acceleration as the reference. Considerable changes in the existing misalignments were observed. It was found that not only misalignments between the sensitive axes changed over time, but due to some micro-movements within the mounting of the printed circuit board with the accelerometer chip, misalignments of the sensitive axes with respect to the mounting datum changed as well. Even though no bigger than 0.6°, the observed misalignments may considerably influence the accelerometer performance, especially in the case of tilt measurements. Some ways of increasing the considered long-term stability of printed circuit board mounting are proposed.