Title :
Reliability of a MEMS torsional ratcheting actuator
Author :
Tanner, Danelle M. ; Walraven, Jeremy A. ; Barnes, Stephen M. ; Smith, Norman F. ; Bitsie, Fernando ; Swanson, Scot E.
Author_Institution :
Sandia Nat. Labs., Albuquerque, NM, USA
Abstract :
A new surface-micromachined actuator, the torsional ratcheting actuator (TRA), has been characterized and stress tested for reliability. The most prominent failure mechanism when running at high speeds (ratcheting frequencies of 333, 1000, or 3000 Hz) is wear on rubbing surfaces leading to adhesion between the ring gear and the alignment guide. We have also observed failure when running at low speeds (5 Hz) due to misalignment of the ring gear, preventing the ratchet pawl from engaging. A wear model was developed which closely predicts the normal force promoting the wear and is in agreement with supporting calculations. We observed multiple ratcheting in the TRA during calibration and solved the equations of motion to confirm that it was due to the moment of inertia of the large ring gear. Damping was also shown to have an effect
Keywords :
adhesion; calibration; damping; internal stresses; microactuators; micromachining; semiconductor device models; semiconductor device reliability; semiconductor device testing; torsion; wear; MEMS torsional ratcheting actuator; adhesion; alignment guide; calibration; damping; failure mechanism; high speed failure; low speed failure; moment of inertia; motion equations; multiple ratcheting; normal force prediction; ratchet pawl; ratcheting frequencies; reliability; ring gear; ring gear misalignment; rubbing surfaces; stress test; surface-micromachined actuator; torsional ratcheting actuator; wear; wear model; Actuators; Adhesives; Calibration; Failure analysis; Frequency; Gears; Micromechanical devices; Predictive models; Stress; Testing;
Conference_Titel :
Reliability Physics Symposium, 2001. Proceedings. 39th Annual. 2001 IEEE International
Conference_Location :
Orlando, FL
Print_ISBN :
0-7803-6587-9
DOI :
10.1109/RELPHY.2001.922886
