Deformation of Center-Anchored Sector Plate with Double Layer Structure Caused by Induced Thermal Residual Gradient Stress

Center-anchored sector plate is widely used as structure in micro deformable focusing mirror, stator and rotor of micro motor, and some electrodes. It is often depositing a metal layer becoming double layer structure. However, due to the mismatch of thermal expansion coefficients between structure and metal layers, residual gradient stresses are induced and make the structure become buckling. Therefore, the devices would have bad performance. In this work, effect of sizes of sector plate on deformation is investigated. There are four angles of sectors are discussed. They are 22.5, 45, 60, and 90 degrees. It is obvious that the profile in radial direction (Lines II, III, and IV) is bent upward. However, profile in axial direction (Line I) has various types. It is found, deformation would decreases as structure layer thickness increasing under constant metal layer thickness in radial direction. And deformation will increase as metal layer thickness increasing under constant structure layer thickness in radial direction. It is found that under different conditions, the profile at free end of sector in axial direction might be curved upward, downward, or even flat. It is found that, the profile at free end in axial direction (Line I) is bent downward with larger sector angles like 90 degrees and bent upward with small sector angles, for example, 22.5 degrees. However, in the center line and both sides of sector in radial direction (Lines II, III, and IV), the deformations increase along the radii and have profile bending upward.