Ceramic microsystems

Knitter, R., Gunther, E., Odemer, C., Maciejewski, U., Ceramic microstructures and potential applications. Microsystem Technol. 2 (1996) 135-138. 

When molded or premolded packages cannot be used for whatever reason, for example, a need for hermetic sealing, modules using ceramic substrates (or PCB-printed circuit board) offer almost unlimited flexibility. They can be used for simple multichip modules containing two or more elements (e.g., a sensing element and an evaluation circuit), may include external components, or may be used to construct complete systems. Stress-optimized package configurations for sensitive microsystems and sensors are no problem (Fig. 5.8.4). 

The present paper siunmarizes the potential of advanced, microsystems compatible piezo technologies for active structures and systems. Examples will be given related to the integration in silicon wafer, ceramic multilayer, polymer and metal matrix architectures. 

Exemplary developments of microsystems as pre-integration platform in smart structure technology are described in the present paragraph. There are two promising approaches seen allowing for the integration of piezoceramic units and electronic circuits, flexible circuits boards and active ceramic multilayer devices. 

Uchino, K. (1996). Recent developments in ceramic actuators, Proc. Workshop on Microsystem Technologies in the USA and Canada, Germany, mst news, special issue, VDIVDE , pp. 28-36. 

Adhesion and thermal expansion are very strongly linked, as the sticking properties at low temperature have certainly an effect on the ability of the catalyst layer to stick at higher temperature. Cracks in the surface, however, can stiU occur while heating the microsystem to the ap>plication temperature. The factors improving the adhesion are basically the same as for the thermal resistance. Often intermediate layers are used to adjust the chemical compatibility between the metal surface and the ceramic catalyst support. 

For the future, the development of synthesis methods aimed at improving reproducibility, reliability and stability of membrane top-layers will have a major impact in inorganic and hybrid membrane production at an industrial scale. In the case of ceramic membranes the control of porosity (micro and meso) and the production of stable nanophase structures seems to be the most challenging objectives. The more recent hybrid membranes can benefit from the recent progress in supramolecular chemistry and are candidate materials for microsystems combining separation, reaction and contactor operations at the micrometer scale. Due to its high versatihty, it is likely that the sol-gel process will remain at the center of these developments. 

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