Empirical reliability assessment of TMR current sensors under combined environmental and electrical stresses

Tunnel magnetoresistance (TMR) current sensors are increasingly implemented in automotive systems and power grid applications; however, their durability under extreme operating conditions remains insufficiently characterized. This study presents an empirical reliability evaluation of two TMR current sensor models, M001 and M003, subjected to combined environmental and electrical stresses. A comprehensive test matrix was designed, encompassing high- and low-temperature storage, temperature-humidity bias, thermal cycling, and exposure to electrostatic discharge (ESD), electrical fast transients (EFT), and surge pulses. Sensor output parameters, including offset voltage and sensitivity, were monitored throughout the testing process, and post-stress failure analysis was conducted using X-ray imaging, scanning acoustic microscopy, and scanning electron microscopy. The results demonstrate that both sensor models retained fundamental functionality following standard stress durations. However, M003 consistently exhibited lower parameter drift and fewer failure indicators than M001 across most testing conditions. Specifically, M001 demonstrated substantially higher offset voltage drift compared to M003 under both high-temperature storage and humidity-bias stress conditions. Furthermore, under ESD and surge pulse stress, M001 devices exhibited signs of dielectric breakdown and metallization degradation, while M003 maintained operational stability with only marginal performance deviations. These findings provide a comparative reliability profile of M001 and M003, underscore the enhanced robustness of M003, and suggest critical areas for design improvement in future generations of TMR sensors.