Experimental validation of external load effects on micro-contact performance and reliability

This paper presents a follow-on study previously presented at the Holm Conference. In the previous work, it was theorized that micro-switch performance and reliability was directly related to the type of external load that was connected. In particular, unintended capacitive loads may discharge at unpredictable times during switch operation and severely degrade or destroy micro-contact surfaces while properly configured loads may actually enhance performance. The severity of this potential vulnerability can be mitigated by purposely including specific circuit elements in various load configurations. This current study is to experimentally investigate and analyze this phenomenon. Using microelectromechanical systems (MEMS) based devices, we have the ability to efficiently and inexpensively fabricate large numbers of identical micro-contact pairs and then connect them to external loads of interest. Using this approach, it was demonstrated that both performance and reliability can be drastically affected by loading. In all cases tested, series inductance and parallel capacitance resulted in premature failure of the micro-contacts tested. Various protective configurations were also tested and all such devices lasted to the targeted 10M cycles of operation with little sign of imminent failure.