The Contact Resistance Performance of Gold Coated Carbon-Nanotube Surfaces under Low Current Switching

Abstract

Multi-Walled CNT (MWCNT) are synthesized on a silicon wafer and sputter coated with a gold film. The planar surfaces are mounted on the tip of a piezo-electric actuator and mated with a gold coated hemispherical surface to form an electrical contact. These switching contacts are tested under conditions typical of MEMS relay applications; 4 V, with a static contact force of 1 mN, at a low current between 20 -50 mA. The evolution of contact resistance is considered in a newly developed test procedure. The contact resistance performance is then linked to a study of the contact changes in the surface. The contact surfaces have been shown to exhibit a transfer process over a large number of switching cycles. The continuous monitoring of contact resistance can be used for the identification of surface failure. The results show that for the surfaces presented the contact resistance remains stable for between 80 and 120 million switching cycles. Interestingly the number of bounces is related to the fine transfer failure mechanism.

Development of a MEMS test platform for investigating the use of multi-walled CNT composites electric contacts

“…For comparison, surfaces without the MWCNTs have also been tested. Further to this, the effect of contact force has been investigated; this work goes some way towards enabling a comparative discussion between new experimental results on a MEMS-type system with previous experimental work [14]. Briefly, in previous work, the contact pair consisted of a fixed gold-coated spherical contact and an Au/MWCNT composite which was adhered to a lead zirconate titanate (PZT) piezoelectricallyactuated cantilever beam [5].…”

“…Due to the long lifetimes (which are of the order of 10 6 up to 10 8 cycles [4,5]) the lifetime testing tends to be highly time consuming. In this work we discuss the design and development of an electrostatically actuated MEMS cantilever beam which enables testing at higher frequencies than our previous experimental rig.…”

Finite Element Model of a Bilayered Gold-Coated Carbon Nanotube Composite Surface

“…2 shows a nominal 300-nm coating section where the Au upper layer has separated as a result of the disruptive sectioning. The roughness (Ra) is approximately 1.3 μm with 500-nm Au coated on 30-μm CNT [8].…”

“…Other functions are unable to provide more informative results, so the determination of the elastic modulus of two layers with functions (4)- (8) are shown to be inappropriate in this paper, therefore adjusting factors are used to simulate the experimental results.…”

Mechanical characterization of a Au coated carbon nanotube multi-layered structure

“…The application of multi-walled carbon nanotubes (MWCNTs) as contact surfaces was first investigated in [6], and then improved with gold-coated surfaces where a forest of CNTs is used to create a compliant under layer to the metallic film. Early studies [7][8][9][10] show that a carbon nanotube coated surface has potential as a contact material for MEMS switches, and can significantly improve the device lifetime.…”