Design of a customized test system to examine the effect of impact force on MEMS switch performance

Abstract

This thesis presents a test system to measure AC and DC characteristics of MEMS switches fabricated at Northeastern University as well as to examine the effect of impact force on the switch reliability. First, the test system was designed and built to be able to quickly and accurately operate a MEMS switch and measure values such as contact resistance, threshold voltage, and off-voltage. These measurements are also used to determine failure-to-open and failure-to-close criteria as well as gate shorts. The system produced has achieved a resistance accuracy of 0.5% at cycle frequencies up to 25 kHz. A commercial voltage amplifier with a slew rate of 30 V/us is used to actuate the switches, while a current buffer is used to supply currents up to 1 A. In addition to creating a universal test system, the effect of the impact force on switch performance was evaluated. A noticeable difference in resistance and off-voltage can be observed, by actuating the gate of the MEMS switch with a soft, ramped waveform with a rise time of 30 us and changing to a hard, stepped waveform with its rise time determined by the slew rate of the gate amplifier and the amplitude of the applied signal, i.e. a 62 V step will require 2 us. This result confirms the hypothesis that a large impact force will cause more adhesion which can lead to device failures sooner in the switch lifetime.