Thick Film Hybrid Integrated Pressure Sensor

The diffusion silicon pressure sensor has widely application, according to it can provide a ratiometric voltage output for detection input pressure and its sensitivity, long term stability, high accuracy. But since the temperature effcet, temperature drift of output signal occures and the performance of silicon sensor is changed, so temperature compensation is necessary in applications. At present, most pressure sensors isolate sensing element from circuit for temperature compensation and signal conditioned, it is difficult to miniaturization and long wire make it easy to be impacted by interference, the aseismatic capability and the reliability of pressure sensor is weakened. This research aims to solve above problems, through fabricating thick film hybrid integrated pressure sensor we can get a grip on the integrated technique that suits for piezoresistive pressure sensor.Firstly this paper discuss the form of zero and sensitivity temperature drift from both semiconductor principle and circuit principle. And the circuit power supply method of integrated pressure sensor is introduced, also the design project of temperature compensation and signal conditioned circuit are mentioned. The circuit diagram of thick film hybrid integrated pressure sensor is presented. After some kinds of technology that manufacture the circuit are considered, the process flow and the main technique requirements are presented in the paper.The thick film hybrid integrated pressure sensor was developed in Shenyang Academy of Instrumentation Science.The sensor circuit contains a current source for transducer excitation, and by means of two point compensation, the output of silicon sensing element is compensated for with the help of resistance network. Considered as a special IC, the pressure sensor integrates diffusion silicon sensing element, circuit for temperature compensation and signal conditioned circuit on a chip in the form of thick film hybrid IC, through using thick film technology and surface mounting technology. After analyzing the testing result, we took measures to adjust corresponding process.The testing result indicates that the sensor performance achieves proleptic goal: output voltage range is 0.25~4.75 V, effective output voltage range is 0.5~4.5 V , accuracy is betterthan 3 %FS . It proves that the design method is correct and the process is feasible.