Tham khảo tài liệu 'the mems handbook (1st ed) - m. gad el hak part 14', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | amount of backlash built into the system. A third problem relates to the ability of the hinge to pivot. Often there is not a large rotational moment to rotate the mirror out of plane when planar hinged structures are connected to planar-surface-micromachined actuators. This means that the designer must take great care to ensure that the hinge always rotates in the correct direction. Failure Mechanisms in MEMS One of the most effective ways we can learn is to learn from our own mistakes. This can be a memorable experience but in the field of MEMS it can be a very expensive and inefficient one. One reason is that the time between design completion and testing is usually measured in months and the price per fabrication run is many thousands of dollars. As of the year 2000 there were only rudimentary modeling and simulation tools available for surface-micromachined mechanisms. This section seeks to share learning obtained at the expense of others by describing some mechanical failures in surface-micromachined mechanisms. The hope is that the reader will gain a deeper appreciation for the complexities of surface-micromachined mechanism design and learn about some of the pitfalls. Vertical Play and Mechanical Interference in Out-of-Plane Structures Surface-micromachined parts typically have a thickness that is very small in relationship to their width or breadth. In the out-of-plane direction the thickness is limited to a few micrometers due to the limited deposition rates of low-pressure chemical vapor deposition LPCVD systems and the stresses in the deposited films. In the plane of the substrate structures can be millimeters across. These factors typically lead to surface-micromachined structures that have a very small aspect ratio as well as stiffness issues in the out-of-plane direction due to the limited thickness of the parts. The result is that designers of surfacemicromachines need to design structures in three dimensions and account for potential .
