High Withstand Voltage Pressure Sensors for Climate Control Systems

Abstract Recently, the need has greatly increased for high-pressure sensors with high withstand voltage for industrial climate control systems. Existing pressure sensors offer high breakdown voltage with complex packaging structure, which compromises their pressure sensitivity, and increases price. This paper describes the development and characteristics of a high withstand voltage pressure sensor based on specially designed silicon strain gauge elements on glass substrate with high dielectric strength. These gauges have a glass backing with high dielectric strength and a coefficient of thermal expansion curve which closely matches silicon single crystal, and a closed shape with four sides, unlike the current competitive devices. This unique design enables very reliable bonds without post-bond misalignment, provide a withstand voltage higher than 2 kV with the usual package structure, but without sacrificing performance or cost. Furthermore, the proposed glass-backed gauges provide great improvement in the electrical performance, especially the thermal drifts of offset and span of pressure sensors. The complete pressure sensor module (0 – 50 bar) containing the silicon strain gauges and conditioning electronics not only meets the high withstand voltage requirements, but also shows 12 mV/V/bar sensitivity, accuracy error of less than 0.30 % FS, 0.07 % FS linearity, 0.03 % FS hysteresis, and 0.10 % FS repeatability at 25 °C, a maximum zero shift of 0.05 % FS, and a span shift of 0.03 % FS.