Mechanical and microstructural characterization of LTCC and HTCC ceramics for high temperature and harsh environment application

Abstract:
In many application fields for micro- and power electronic devices, ceramic materials become more and more relevant for packing of electronics with focus on high power, high temperature or harsh environmental ambient conditions. At moderate ambient conditions the material behavior of many ceramic materials is well known and data for construction design and numerical reliability estimation is available in literature. Nevertheless for high temperature usage up to 500deg C or exposure to harsh environments the thermo-mechanical material behavior as well as related failure criteria can significantly differ depending on the specific material composition. In this paper, three representative types of ceramics were characterized at temperatures up to 500deg C with respect to their thermo-mechanical behavior and potential failure modes caused by thermo-mechanical stress or degradation by harsh environmental conditions. Therefore, major engineering relevant, temperature dependent properties -like Young’s modulus, coefficient of thermal expansion, fracture strength at high temperature or after water quenching and superficial hardness- were determined allowing a better understanding of the effective mechanical robustness and potential degradation mechanism. In addition, observed degradation mechanisms were analyzed by analytical high resolution techniques like SEM, EBSD and TEM to get a better understanding of the microstructural correlation.