Microsystems are a breakthrough in integration of functional devices in different industries like telecommunications, sensor technologies and others. Processing technologies are similar to IC technology but the variety of materials is still larger. Furthermore, microsystems may operate at high temperatures and in aggressive environments, like certain gas sensors, or have to withstand external forces, like pressure sensors. From a point of view of mechanics and materials science, the functional reliability of such systems is not obvious. Often highly sophisticated analysis and characterization tools are needed in order to gain a fundamental understanding of the physics of micro- and nano-structures, to control materials, packaging, and functionality during manufacturing and to perform reliability testing for lifetime estimation.