A Highly Reliable MEMS Relay With Two-Step Spring System and Heat Sink Insulator for High-Power Switching Applications

Abstract

This paper reports a highly reliable electrostatic microelectromechanical systems (MEMS) relay for high-power switching applications. The main proposal to elevate reliability is to reduce thermal damage in the contact area. Since a contact resistance is the key parameter determining the amount of Joule-heating and the corresponding thermal damage, we devised a unique spring structure to maximize the contact force (resulting in a low contact resistance) using a reasonable actuation voltage named a two-step spring system. Another important feature was applied to alleviate Joule-heating, which is to use an insulator having high thermal conductivity to dissipate the generated heat efficiently, named a heat sink insulator. The fabricated MEMS relay exhibited 2 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\text{m}\Omega $ </tex-math></inline-formula> in contact resistance, which is the lowest level reported so far with an actuation voltage of 45 V. Reliability was remarkably enhanced over ten times by the heat sink insulator. Consequently, by applying these two approaches simultaneously, the fabricated MEMS relay was successfully operated up to the <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$5.3 \times 10^{6}$ </tex-math></inline-formula> cycles at 1 V/200 mA in ambient air and hot switching condition, which is the highest reliability reported at that power level. [2015-0237]