Mechanical, Thermal, and Material Influences on Ohmic-Contact-Type MEMS Switch Operation

Microswitch performance and reliability are affected by the coupled influences of actuator properties, material and process properties, and device thermal properties. Different contact materials show large differences in immunity to contamination. Contact shape and the adherence force between contact surfaces both evolve as the contact pair is cycled, with the adherence force often reaching a maximum between 10
⁵
and 10
⁷
cycles for gold. A typical switch actuation with a step function voltage results in an contact impact force 5 times greater than the static force, increasing the adherence force and the rate of change of the shape of the contact. Heating of the conductors in the switch results in intermodulation products, which are small at a transmitted power of 1 W, but increase with increasing power levels.