Design And Research Of Ceramic Packaging HTCC High Temperature Pressure Sensor

At present,in the military,traffic management,aerospace and other fields,there are high temperature and high pressure and other harsh environments.Monitoring changes in temperature and pressure parameters is of great significance to improve efficiency and the safe operation of the system.Existing sensors are limited by material properties and signal extraction methods,and it is difficult to meet the test requirements in high temperature environments.Ceramic-based passive sensors fabricated using multi-laminate technology have great advantages at high temperatures.The research group has studied ceramic-based inductive-capacitive(LC)passive sensors for many years.The main representatives are LTCC-based sensors and HTCC-based sensors.However,when the device under investigation is tested at a high temperature,there is a problem that the signal extraction is unstable because the interrogating antenna and the sensor are difficult to fix.Therefore,in order to realize the practical application of the sensor under high temperature,this paper presented a HTCC high temperature pressure sensor packaged by ceramic,and focused on the design and research of the package structure of high temperature pressure sensor,which was of great significance to the practical application of the LC sensor.Based on the principle of LC resonance,the signal extraction method of high temperature pressure sensor was analyzed.The theoretical analysis of the plane spiral inductance model and the parallel plate capacitor model in the sensor circuit were carried out respectively.The common capacitance model of LC passive pressure sensor was introduced.The pressure sensitive principle of the sensor was analyzed.At the same time,the testing principle of the ceramic package structure was analyzed.By studying the electromagnetic theory,the structure of a high temperature pressure sensor based on HTCC was designed.The mechanical model of the pressure-sensitive element of the sensor was studied,and the theoretical calculation was proposed.At the same time,ANSYS mechanical simulation was performed on the pressure-sensitive structure.The HTCC micro-assembly process was introduced.The sintering experiment was performed on the substrate for several times and the sintering process curve was obtained.The sensor was prepared.According to the design requirements of the package structure,a ceramic package structure of a high temperature pressure sensor was designed.The encapsulated structure was prepared by a ceramic mechanical finishing process,and the sensor was encapsulated and tested for stress.From the test results,the sensor resonant frequency showed a good linearity with the pressure change,and its pressure sensitivity was about 0.458MHz/bar.From the room temperature to 700 °C,the package structure was subjected to five repeated high temperature tests.The results showed that the repeatability of multiple tests was good,which proved that the packaging structure had high reliability;and at 700 °C,the sensor still had about 7dB signal,indicating that the ceramic package structure of sensor had the potential to work in high temperature environments.