Mechanical and tribological characterizations for reliability design of micromembranes

This paper presents the study of mechanical and tribological behavior of micromembranes supported by serpentine hinges used in optical and communication applications. Micromembranes with different geometrical configurations, supported by two and four hinges are investigated in order to determine their static response under mechanical loadings. The micromembranes stiffness was experimentally investigated using an atomic force microscope. Widely used in micro-switches, these micromembranes are deflected until substrate to close a circuit and transmit a signal. The main failure causes of micromembranes which are directly deflected to substrate are the excessive stress in hinges and stiction. Simulation of the micromembranes mechanical behavior is important for performance optimization and to improve their reliability design. Numerical simulation of micromembranes is presented in paper to estimate the stress distribution in hinges and its maximum value. The geometrical dimensions of hinges have influence on the micromembrane´s mechanical response and on stiction. The adhesive force between micromembrane and substrate depends on the mechanical restorative force given by the hinges stiffness.