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Open AccessArticle

Transient Contact Opening Forces in a MEMS Switch Using Au/MWCNT Composite

Mechanical Engineering, University of Southampton, Southampton SO17 1BJ, UK
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Technologies 2019, 7(4), 69; https://doi.org/10.3390/technologies7040069
Received: 29 August 2019 / Revised: 15 September 2019 / Accepted: 19 September 2019 / Published: 23 September 2019
(This article belongs to the Special Issue Microswitching Technologies)
Most failures in micro electromechanical system (MEMS) switches can be attributed to the degradation of contact surfaces and sticking contacts. A wear-tolerant composite contact material, composed of a Au film supported by multi walled carbon nanotubes (Au/MWCNT), has been engineered to provide wear resistance and enhanced switching lifetime with conductive properties close to pure Au. Switching lifetimes of billions of cycles have been demonstrated, representing greatly increased performance over thin film Au. Below the arcing threshold (~12 V) the wear mechanism has been shown to be a combination of the fine transfer of contact material by the molten metal bridge (MMB) phenomenon and a delamination of the Au. In this study, the composite contact is hot switched at low current DC conditions (4 V DC and 20 mA) while the contact force is measured at the micro Newton scale in nanosecond resolution. The characteristic voltage waveform associated with the MMB is observed with forces detected as the contact softens, melts, and separates. The presence of a delamination event (DE) is also observed, where the contact opens abruptly with no MMB phenomenon apparent. The DE contact openings are associated with a transient peak force of 21.6 ± 2.3 µN while the MMBs are linked to a lower peak force of 18.1 ± 2.5 µN. View Full-Text
Keywords: MEMS switching; molten metal bridge; surface wear; DC switching; hot switching; low current switching; contact sticking; contact forces MEMS switching; molten metal bridge; surface wear; DC switching; hot switching; low current switching; contact sticking; contact forces
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Bull, T.G.; McBride, J.W. Transient Contact Opening Forces in a MEMS Switch Using Au/MWCNT Composite. Technologies 2019, 7, 69.

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