Understanding fracture of brittle solids: from single crystals to ceramic systems

Reference	Presenter	Authors (Institution)	Abstract
09-109	Raul Bermejo	Bermejo, R.(Montanuniversitaet Leoben);	To satisfy the demand for higher up- and download rates in modern smartphones, communication providers expand their utilized frequency bands for new generation mobile phones. The wider portfolio of used frequency bands lead to a significantly increased number of frequency filters in modern devices with increased demand for precise, efficient and cheap filter components. Two main parts of the microelectronic system are (i) the ceramic printed circuit board, and (ii) the functional (single crystal) components mounted on the board. The wide range of used material classes (e.g. polymers, metals, ceramics, single crystals) with different thermo-mechanical properties can lead to significant mechanical stresses after cooling down from production or due to thermo-cycling during qualification or service. Especially for the case of brittle materials there is always a certain chance for failure once a mechanical stress is applied. In this context, the goal of the present work is to gain a deep understanding on the failure and deformation mechanisms occurring in the brittle parts integrated in ceramic-based microelectronic systems. A combination of macroscopic and micro-scaled testing yields understanding of the effect of environment, architecture, crystal orientation and material properties anisotropy on the fracture response and reliability of the different parts of the microelectronic system. For the ceramic board, the experimental findings revealed a significant effect of humidity on the subcritical growth of defects over time as well as a crucial influence of the architecture (e.g. metallization) on the strength distribution of the ceramic material. For the single crystal functional components, the strong anisotropy in thermo-elastic properties along with the crystal orientation with respect to the loading axis dictate their mechanical behaviour.
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