Contact materials for microrelays

The design of a microrelay actuator has to be based on the characteristic data of the contact material used. These data were determined experimentally at Au, AuNi5 and Rh switching electric contacts. The samples were cleaned with good result using the "Schaltreinigung" procedure. A new precision measurement technique was developed that enables investigations of electric contacts at contact forces varying continuously in the range from 0.1 mN to more than 10 mN. It was found that AuNi5 and Rh are contact materials well suited for microrelays, whereas Au is not appropriate due to its high adherence. Stable contact and reliable opening are provided by forces altogether as low as 0.6 mN. The experimental data were used successfully in dimensioning the moving wedge actuator used in silicon microrelays.