Design and application of flexible stops for MEMS devices

As part of the reliability investigation, shock tests for first generation surface micro-machined devices have been performed which showed susceptibility regarding stiction at the stopper elements and breakage of adjacent anchor points to the substrate. This paper clearly demonstrates how the application of compliant travel stops can solve these issues but it also points out limitations of this approach. A numerical model has been developed to help understand the events during a shock load and the working principle of compliant stops. Compared to the previous work of Yoon et al., this investigation gives a practical guideline regarding application and dimensioning of flexible stops and adjacent anchors at MEMS products where available design space is limited and structural deflections are restricted. Furthermore, it gives the possibility to take viscous damping and different pulse shapes as well as durations into account.