The present invention is a thermally controlled switch with high thermal or electrical conductivity. Microsystems Technology manufacturing methods are fundamental for the switch that comprises a sealed cavity formed within a stack of bonded wafers, wherein the upper wafer comprises a membrane assembly adapted to be arranged with a gap to a receiving structure. A thermal actuator material, which preferably is a phase change material, e.g. paraffin, adapted to change volume with temperature, fills a portion of the cavity. A conductor material, providing a high conductivity transfer structure between the lower wafer and the rigid part of the membrane assembly, fills another portion of the cavity. Upon a temperature change, the membrane assembly is displaced and bridges the gap, providing a high conductivity contact from the lower wafer to the receiving structure.