Research On Process And Performance Optimization Of Stainless Steel Pressure Sensor Based On Thick-film Technology

Thick-film pressure sensor (TFPS) has been developed for more than40years. Duringthis period, the research on the theory of this technology goes deeper and deeper. Therefore,broader applications have been found in different fields, especially in automotive electronics,one of the most important applications. In early time, thick-film pressure sensor was mainlybased on96%Al2O3ceramic substrate, which is still widely in use nowadays. Onedisadvantage of Al2O3ceramic substrate is its brittleness..With the development ofthick-film ink system, a new type of thick-film pressure sensor, based on steel substrate, hasbeen proposed, which has not been reported due to its proprietary nature. However, effortshave been made in this direction among the domestic research organizations and companies.The relative research, in this paper, is conducted under the support of Fine MEMS Inc.On the basis of overall research on the characteristics of thick-film ink system,fabrication processes and working principle of TFSPS, researches on the processes,optimization and performance of TFPS have been carried out by the combination of finiteelements analysis and experiments. The major research is summarized below:(1) On designing of pressure sensor: Fundamental working principle is thoroughlyinvestigated, with consideration of small deflection theory, piezoresistive effect of thick-filmresistor (TFR) and Wheatstone bridge;(2) On fabrication of pressure sensor: Fabrication process is designed, advancedscreen-printing and thick-film ink system are taken consideration;(3) On the compatibility between thick-film layer and steel substrate: Analysischaracteristic of the interface between thick-film dielectric layer and steel substrate;(4) On the layout of thick-film resistors: Model the stress and strain distribution of thesteel substrate, accordingly, some samples of TFSPS have been produced; and(5) On the performance of thick-film steel pressure sensor (TFSPS): Test and analysisthe performance of TFSPS among full temperature range (-40℃~125℃). The full pressurerange of the pressure sensors have been calibrated through test results. Failure modes of the sensors have been analyzed; and we put forward some methods, aiming at optimizing theperformance of the sensors.