SIZE EFFECT ON STIFFNESS AND PULL-OFF FORCE OF THERMALLY ACTUATED GOLD CANTILEVERS
Journal Title: ROMANIAN JOURNAL OF TECHNICAL SCIENCES - APPLIED MECHANICS - Year 2017, Vol 62, Issue 2
Abstract
This paper focuses on revealing the size effect on the mechanical behavior (i.e. bending stiffness, Young modulus, pull-off force) of gold cantilevers with lengths ranging from 190 µm to 490 µm. We investigated the temperature influence (from 20°C to 100°C) on the mechanical behavior of thermally actuated microcantilevers by using an atomic force microscope. The investigated cantilevers are fabricated from gold with a width of flexible part equal by 35 µm and a thickness of 2 µm. The flexible part of cantilever is suspended at 2 µm above a silicon substrate. The beam anchor has a rectangular cross-section with the side of 110 µm and the thickness of 4 µm. A nonlinear variation of the bending stiffness of microcantilevers as a function of temperature is experimentally determined. The variation of the pull-off force between microcantilevers and substrate is monitored at different temperatures. Finite element analysis is used to visualize the thermal field in microcantilever and to compute the axial expansion. It was noted that the relaxation of the modulus of elasticity of microcantilevers with temperature is slightly higher. This investigation was found to be more versatile since it yielded additional information about the structure and material properties. The results obtained in the study are important in order to enhance the design of MEMS and to increase their reliability and the lifetime. Moreover, the results are extremely useful in understanding and controlling the mechanical characteristics of sensing/acting microcomponents under thermal operating conditions. The results are promising for applications in MEMS where accurate properties of the thermally actuated MEMS cantilevers are required within extended temperature range.
Authors and Affiliations
CORINA BIRLEANU, MARIUS PUSTAN
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