Dynamic Behavior of Condenser Microphone Under the Influence of Squeeze Film Damping

Abstract

This paper investigates the effect of squeeze film damping on a micromechanical structure that oscillates due to the pressure distribution on moveable top plate that pair with perforated backplate. The damping characteristics are analytically evaluated to establish the optimum design that increase dynamics performance. The squeezed film damping governing equation, the Reynolds equation, is the fundamental equation of this work. The damping coefficient, air gap damping and viscous damping are calculated by using Skvor's formula. The size of perforation holes and air gap thickness that influencing the squeeze film damping were studied. Analytical solution with various holes structure are summarized. Overall, the 3μm of hole radius, 50μm of holes center-to-center distance and 4μm of air gap thickness were found to be the best in order to reduce squeeze film damping in capacitive microphone.