Accelerated testing of multi-walled CNT composite electrical contacts for MEMS switches

The use of gold-coated multi-walled carbon nanotube (Au/MWCNT) bilayer composite surfaces has been discussed in previous work as a method for improving the reliability of switch contacts [1, 2]. A consequence of large lifetimes means that testing to failure is time consuming. To address this we developed a MEMS-based test platform which enables testing at high frequency [3]. The MEMS devices were developed in a two stage process. In this paper the results obtained from the first stage design for a MEMS-based test platform device are discussed. Further to this, an overview of the design of the second stage device is given. Using the first-stage device, at a current of 50 mA (at 4 V), the composite yielded a lifetime in excess of 44 million hot-switching cycles [4]. At a lower load current of 10 mA, the contact maintained a stable contact for >500 million hot-switching cycles. As well as monitoring the contact resistance, SEM images of the surface before and after testing are presented. The first stage MEMS-based developmental device is a step towards a smaller integrated and packaged high-lifetime metal-contacting MEMS switch. An overview of the considerations for the redesign is given with a discussion on the predicted performance and improvement for accelerated switch testing.