Thick-film Transducers

University of Southampton Institute of Transducer Technology

Thick-film Transducers

Sensor development continues to expand and is largely driven by the advances in the field of microelectronics. The phrase "solid state sensor" tends to conjure up the picture of silicon-based devices. Indeed, silicon planar technology is widely used in the fabrication of many of today’s sensors . It possesses many desirable characteristics for sensor applications. Standard processing techniques can be used and the technology provides a high degree of integrability into microelectronic sensor sub-systems.

Presently, the major drawback of silicon sensors concerns their ability to provide a cost-effective solution to a particular problem. If the demand is sufficiently high (in the order of several million sensors per year) then this is not the case. Low to medium volume requirements (say a few tens of thousands of sensors per year) are a different matter and can only be justified under special circumstances.

Thick-film technology was introduced about thirty years ago as a means of producing hybrid circuits. Such circuits comprise semiconductor devices, monolithic ICs and other discrete devices in addition to the thick-films themselves. A key factor distinguishing a thick-film circuit is the method of film deposition, namely screen printing, which is possibly one of the oldest forms of graphic art reproduction.

Thick-film hybrid circuits are generally regarded as being compact, robust and relatively inexpensive and have found application in areas such as televisions, calculators, telephones, automotive electronics and missile guidance systems to name but a few. Thick-film sensors are a relatively new application of the technology, with a majority of the published working appearing in the past decade. The major emphasis of the work undertaken in this group has been in the area of physical sensors. It should be noted however, that the technology is also widely used for the fabrication of chemical and gas sensors and many commercial devices exist. The integrability of the technology also allows combination with other enabling technologies, such as silicon, to provide powerful and economically viable solid state sensors. Some of the work done in this area will be described on this we site.