INFLUENCE OF THE BONDING CONDITIONS ON THE RESPONSE OF CAPACITIVE PRESSURE SENSORS

The behaviour of a capacitive pressure sensor built from a deformable silicon plate bonded to a Pyrex 7740 substrate has been simulated nume rically with finite-element calculations. The comparison of 3D simulat ions with experimental data has shown the validity of the numerical mo del used for the simulations. By carrying out st structural analysis w ith these tools, it has also been revealed that silicon and Pyrex exhi bit substantial deformations in the neighbourhood of their bonding whe n a pressure is applied on the sensor. If these deformations did not o ccur, the sensitivity of the sensor would be divided by 2.1, its measu rement range would be multiplied by 1.68 and its linearity would be si gnificantly increased. It is inferred that the response of most pressu re sensors is influenced by the deformations of the diaphragm bonding.