Highly reliable O-ring packaging concept for MEMS pressure sensors

We present a highly reliable packaging concept for piezoresistive differential pressure sensors. The use of O-ring clamping as a hermetic sealing on coated MEMS pressure sensors provides a very powerful packaging concept applicable in various environments including wet aggressive media. Even relatively large misalignments of die and O-rings only induces an additional output offset less than 0.3% of maximum output. Furthermore, only an offset change less than 0.4% of maximum output in the applied range of O-ring compression forces. In addition, the sensor output shows a small linear dependency on absolute media pressure with a contribution less than 1.5% of maximum output. In conclusion, O-ring clamping is found to be a long-term reliable packaging concept. Many of the experimental findings are supported by 3D FE-simulations.