Key Technology Research Of LTCC High-temperature Pressure Sensor

High-temperature pressure sensor is a device which has a broad application prospects inthe area of civil industry such as automotive, aeronautics and national defense and also is oneof the main MEMS products. Compared to conventional pressure sensors, wireless passivehigh temperature pressure sensor has a huge advantage in harsh environment.High-temperature characteristics of LTCC (low temperature co-fired ceramic) wirelesspassive temperature pressure sensor and coupling distance of the wireless signal were studiedin this paper, it has an important significance in the measurement of pressure in harshenvironment.The common structure of the pressure sensor, pressure sensor principle and the basicprinciple of the wireless signal read were described based on current research. The key designprinciples of the sensor were described and the key technologies of sensor manufacturingprocess were analyzed and studied.The coupling distance characteristics of sensor wireless signal were studied in this paper.The test platform of coupling distance was designed. The impacts of the coil inner diameter,the coil outer diameter, the coil width, the number of coil turns and the shape of coil on thecoupling distance were studied when the parameters of the read antenna coil and thesensorinductance coil were same and different. The value of geometry parameters of the inductancecoil was recommended according to the experiment results. The relationship betweencapacitance, inductance, resistance and quality factor was simulated by MATLAB softwareand the impacts of capacitor, inductor and resistance on the coupling distance were verifiedthrough experiment. The coupling effect and coupling distance were enhanced by placing aferrite with a bigger area than antenna behind the antenna. Experiment results showed that themethod could enhance the coupling effect between reader antenna sensor and increase thecoupling distance.The high-temperature characteristics of sensor were studied in this paper. The test systemof high-temperature characteristics of the sensor was designed. The sensor was measured from room temperature to600℃and the test results showed that the resonant frequency of thesensor had an obvious change at elevated temperature. The reasons of the temperature drift ofsensor resonant frequency were obtained after the analysis of the test results. A test methodof temperature characteristics of LTCC material dielectric constant was proposed and theLTCC material dielectric constant was tested at elevated temperature. The sensor structure isoptimized according to the reasons of temperature drift of sensor resonant frequency. Theoptimized sensor was tested at elevated temperature and the results showed that the resonantfrequency had a smaller temperature drift. The factors affecting coupling effects betweensensor and antenna under temperature were analyzed in this paper.