High-precision ceramic pressure sensor

Abstract

The invention discloses a high-precision ceramic pressure sensor which comprises a ceramic baseplate containing a concave hole and a plurality of electric-conductive through holes as well as a ceramic thin plate combined on the side of the ceramic baseplate where the concave hole is located, a measuring electrode and a first annular electrode winding the measuring electrode are disposed on a concave face of the concave hole, a moving electrode and a second annular electrode winding the moving electrode are disposed on the face of the ceramic thin plate which is opposite to the concave face, leading-out ends of the measuring electrode, the first annular electrode, the moving electrode and the second annular electrode are respectively led out from the other side opposite of the ceramic baseplate which is opposite to the concave hole via the corresponding electric-conductive through holes, the moving electrode and the measuring electrode constitute a measuring capacitor, the moving electrode and the first annular electrode constitute a reference capacitor, and the first annular electrode and the second annular electrode also constitute an isoelectric face through short circuits of the electric-conductive through holes. The high-precision ceramic pressure sensor disclosed by the invention can control an electrode spacing within a very high precision scope without introducing any second material, and has high sensitivity and good sealing effects.

Description

technical field [0001] The invention relates to a pressure sensor, in particular to a high-precision ceramic pressure sensor. Background technique [0002] The control accuracy of the spacing between two ceramic sheets is fundamental to ensure the static capacitance, application range and accuracy of this type of ceramic pressure sensor. At present, the method of controlling the spacing between two ceramic sheets relies on the introduction of a second material on the substrate to form the required spacing for parallel plates. Materials such as ceramic balls, resin balls, low temperature co-fired (LTCC) ceramic sheets, ceramic quilts, spacers, etc. are sintered together with substrates and sheets by hot pressing, and the final thickness of the introduced material is required between parallel plates. The final spacing, due to the uncertainty of the shrinkage rate in the Z-axis direction of the material due to the influence of pressure, sintering temperature and other factors, ...

AI Technical Summary

Problems solved by technology

[0002] The control accuracy of the spacing between two ceramic sheets is fundamental to ensure the static capacitance, application range and accuracy of this type of ceramic pressure sensor. At present, the method of controlling the spacing between two ceramic sheets relies on the introduction of a second material on the substrate to form the required spacing for parallel plates. Materials such as ceramic balls, resin balls, low temperature co-fired (LTCC) ceramic sheets, ceramic quilts, spacers, etc. are sintered together with substrates and sheets by hot pressing, and the final thickness of the introduced material is required between parallel plates. The final spacing, due to the uncertainty of the shrinkage rate in the Z-axis direction of the material due to the influence of pressure, sintering temperature and other factors, this method is difficult to ensure the control of the final spacing, and the sensor needs to undergo repeated pressure shocks, and the second material is easy to appear Sensor failure due to differences in parameters such as thermal expansion coefficient, elastic modulus, compressive strength, and ceramic materials

[0003] The electrode pattern design on the two ceramic bodies is another important factor affecting the output mode and accuracy of the pressure sensor. At present, the electrodes of this type of ceramic pressure sensor are printed on two pieces of ceramics, one thick and one thin, to form a parallel plate structure. The electrodes use a common Electrode, a measuring electrode, a reference electrode three-electrode structure, this structure can use single-point output, but can not eliminate the influence of stray capacitance on the reference capacitance, when the capacitance value of the sensor chip itself is small, the stray capacitance value is often higher than the chip The self-capacitance is even larger, which makes it difficult to guarantee the final output accuracy of the sensor

[0004] The ceramic pressure sensor that uses air as the medium between the two electrodes, the static capacitance value of the sensor with air as the electrode medium is small, the output capacitance change value is small under the same pressure, the sensor output sensitivity is poor, and the electrode will be damaged under the overload pressure There is an electrode short circuit phenomenon, and the occurrence of a short circuit can easily cause the signal processing circuit of the sensor to burn out

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