FIRST RESULTS ON A MONOSTABLE THERMALLY ACTUATED PARAFFIN-BASED SPST SWITCH FOR COPLANAR WAVEGUIDES
M. Sc. JOHAN BEJHED, A. RYDBERG, H. KRATZ

Abstract. Performance evaluation of switches has been mainly concerned with switching time, power handling, cold or hot switch function, material stability e.g. electromigration, frequency range, insertion loss, return loss, isolation, actuation power e.g. pull-down voltage, and reliability. In the case of high power handling switches, selfactuation i.e. changes of the switch state initiated spontaneously and wrongly by the device itself is a major concern. Presented in this paper is a SPST switch based on a thermal actuation mechanism with large actuation distance, more than 20 μm, enabling a low influence on the transmission line if the switch is in the OFF state. The actuator type has previously proved to be of high force and hence an excellent metal to metal connection between the switch and the substrate metallization is enabled. Mechanical problems such as fatigue found in e.g. copper bridges are avoided with this choice of actuator. Encapsulated paraffin in bonded monocrystalline silicon, where actuation is provided by the volumetric expansion of paraffin at the melting point, is a mechanical structure lacking most of the classical problems of fatigue in other types of actuation mechanisms.