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Integrated Hybrid Pressure Sensor Using a Piezoresistive Thickfilm Sensor Element
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English
Abstract
High-performance electronic systems for automotive engine control largely depend on the existence of qualified sensors. Together with actuators they determine the efficiency, reliability and also the costs of the entire system.
In addition to the engine speed, the air flow through the intake manifold and the throttle-valve position, the absolute manifold pressure is an important input parameter for engine-control systems. Appropriate pressure transducers have to be made available for several pressure ranges, e. g. 100 kPa and 200 kPa, and packaged in suitable housings, especially as an on-board component for insertion into electronic control units.
On the basis of thick-film technology - well established in the production of automotive microcircuits /1/* - we present a new generation of integrated hybrid pressure sensors.
A novel thick-film process was developed, to build up self-supporting micromechanical structures of dielectric materials onto a ceramic substrate. A miniature diaphragm of about 5 mm diameter and 0.1 mm thickness can be produced by applying several screen printing and firing sequences. Together with the substrate it forms a hermetically tight, bubble-like cavity of 60 µm in height. Piezo-resistive thick-film resistors are printed on the center of the diaphragm. With a gauge factor of 15 they transform the mechanical tension, caused by changes of the ambient pressure, into an electrical signal. Both the sensor element and an electronic signal-conditioning circuit are integrated on one ceramic substrate without additional bonding. The housing, in which the hybrid circuit is mounted, consists of two parts. It is made from glass-reinforced thermoplastic material with excellent mechanical strength. The entire sensor has a weight of only 15 g.
Technology, construction details and performance of the new device are presented in this paper.
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Authors
Citation
Glas, H., Kuhnt, W., and Stecher, G., "Integrated Hybrid Pressure Sensor Using a Piezoresistive Thickfilm Sensor Element," SAE Technical Paper 870286, 1987, https://doi.org/10.4271/870286.Also In
References
- Bergfried D. E. Mayer U. Schleupen R. Werner P. “Engine Management Systems in Hybrid Technology” SAE international Congress Detroit 1986 Paper 860593
- Lee K. W. Walker B. E. “Silicon Micromachining Technology for Automotive Applications” SAE international Congress Detroit 1986 Paper 860470
- Holmes P. J. “Changes in Thick-film Resistor Value due to Substrate Flexure” Microelectronics and Reliability 12 395 1973
- Prudenziati M. Morten B. “Piezoresistive Properties of Thick-film Resistors. An Overview” Hybrid Circuits 10 20 1986
- Dell'Acqua R. Dell'Orto G. Vicini P. “Thick-film Pressure Sensors: Performances and Practical Applications” Third European Hybrid Microelectronis Conference (ISHM) Avignon 1981
- Deli'Acqua R. Dell'Orto G. Forlani F. Puzone A. Canali C. “Characteristics and Performances of Thick Film Pressure Sensors for Automotive Applications” SAE international Congress Detroit 1982 Paper 820319
- Di Flore A. Haskard M. R. “Thick film pressure transducers” Microelectronics Journal 17 35 1986