Reliability estimation of thin film platinum resistance MEMS thermal mass flowmeter by step-stress accelerated life testing

Abstract

Assuring reliability is a key aspect of sensor quality. In this article, we introduce the reliability test results of thin film platinum resistance (TFPR) MEMS thermal mass flowmeter based on accelerated life testing (ALT). The influences of temperature stress (Ts) and temperature-voltage double-stress ((T + V)s) on sensor reliability are assessed through ageing experiments using a climatic chamber. According to the performance in ageing test, we chose output voltage as a characteristic parameter. We analyze the causes for degradation of the characteristic parameter. In addition, based on Arrhenius model and Weibull distribution (WD), we predict the lifetime and estimate the reliability of the TFPR MEMS thermal mass flowmeter. The average lifetime of Ts group is 1.826 × 104 h (2.085 years) in 85 °C test conditions; and the (T + V)s group is 1.003 × 104 h (1.145 years). The reliability of Ts group is 87 %, and the (T + V)s group is 80 %, in the first working year. The results reveal the temperature and voltage stress influences on lifetime. This research provides a good way for reliability analysis of thermal mass flowmeter units.