Shock Protection Using Integrated Nonlinear Spring Shock Stops

This paper reports the fabrication and testing of integrated nonlinear spring shock stops to protect micromachined devices. This approach enables a generic batch micro-packaging technology providing superior shock protection over conventional hard shock stops, and can be conveniently integrated with micromachined devices without additional fabrication processes and excessive area expansion. These advantages are demonstrated by integrating the nonlinear spring shock stops with a capacitive and with a piezoresistive MEMS accelerometer fabricated by different processes. Conducted shock tests reveal that the nonlinear stops provide substantial device survival rate (83%) compared with hard stops (8%). The device fracture mechanisms are also identified