Evaluating the influence of current on the wear processes of Au/Cr-Au/MWCNT switching surfaces

Wear processes of the switching contact pair consisting of a gold layer on multiwall carbon nanotubes (Au/MWCNT) and a chromium and gold coated hemispherical ball (Au/Cr) are evaluated over a range of current conditions. The switching experiments were conducted using typical conditions for a MEMS relay application, i.e. 4 V, with static contact force 1 mN with currents level of 20 - 200mA. The Au coated MWCNT substrate exhibited a transfer process over a large number of switching cycles. On the assumption that the transfer process was a combination of a fine transfer and delamination processes; a previous experimental investigation was considered by dividing the wear processes into four stages of a failure behavior. It is observed that the fine transfer process dominates in the unstable and stable contact resistance stage and then the delamination dominates in the rising stage and a failure process. The increase of contact resistance was used to identify contact failure