Papers by Author: Andreas Schönecker

Abstract: Microelectronic substrates like silicon, alumina and LTCC (Low Temperature Cofired Ceramics) allow for high robustness and reliability, 3D packaging (electrical connection, channels, cavities and membranes) as well as integration and application of electronic components whereas piezoceramic materials offer sensor and actuator operations. To combine the advantages of both, integrated solutions are of great interest. This paper deals with two approaches of monolithic integration, (i) screen printing of piezoceramic thick films on microelectronic substrates and subsequent post firing and (ii) integration of pre-fired piezoceramic components into green LTCC multilayer packages and subsequent sintering. Functionality of smart microsystems not only depends on the outer design and construction but to a great part on interaction of substrate and piezoceramic material properties. A thorough choice of materials as well as the understanding and prevention of chemical reactions are necessary to build effective systems.

Abstract: Piezoceramics are considered as key functional material in micro systems and smart structure technology. Showing superior mechanical, dielectric, pyroelectric, ferroelectric and piezoelectric properties they introduce improved functionality, e.g. sensing, actuation, energy harvesting, health monitoring or shape control. Various applications such as micro integrated valves, drives, voltage converter, piezoelectric, pyroelectric and ultrasound sensors are expected. Another field of application concerns active structures in space, automotive or machine building industry. Progress was achieved by combining flexible board and piezo technology which opens up a new class of reliable ready to use actuator and sensor modules. Tailored design and packaging are seen as key factors for progress in custom applications. Load carrying structures with embedded actuators, sensors and electronics, which are usually pre-integrated in modules, offer the opportunity for noise reduction, vibration and shape control and health monitoring. The present paper summarizes the potential of advanced, microsystems compatible piezotechnology for active structures and systems. The focus will be given to PZT film and fibre processing and the integration in silicon wafer, ceramic multilayer and polymer matrix architectures. Finally, forward-looking applications are highlighted.

Abstract: The complex, non-linear, irreversible, hysteretic behaviour of polycrystalline ferroelectric materials is the result of domain wall motion and correlates with the phase composition of the ceramic. This paper reports on our investigation of the ferroelectric polarization of PZT ceramics in dependence of temperature in the range between -175 and 150°C. We compare five commercial piezoelectric materials used in actuator applications. The obtained data, derived correlations, and material functions are very helpful for understanding the material properties in practical applications and give input values for temperature depended numerical hysteretic models [1].