Equivalent strengths for reliability assessment of MEMS structures

Abstract The scattering and inconsistency of tested strength of brittle microelectromechanical systems (MEMS) materials imposes a critical obstacle for structural reliability assessment of MEMS devices. In this article, the nature of such a discrepancy and the effort to solve this issue are discussed. A method based on equal failure probability is proposed to map the material strength obtained from test specimens to the equivalent strength for MEMS structural design. This conversion can be classified into three types to deal with difference in size, geometry, and applied loadings manner and the possible approach to form a material strength database for brittle MEMS material is suggested. The weakest link theory and Weibull statistics are adapted for illustrating the proposed data reduction process. Several examples are provided to illustrate the possible applications of this work. Finally, an equivalent safety factor concept is proposed to promote probabilistic structural design and the perspective to achieve a MEMS material strength database is discussed.

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