Electrosurgical devices are disclosed herein in which one or more electrodes are separated from adjacent portions of the device by a phase change material. The phase change material can be a solid at room temperature that melts at operating temperatures, forming intimate contact at the interface between the electrode and the adjacent portion of the device to produce low thermal resistance. The phase change material can have a high dielectric strength which electrically isolates the electrode from adjacent portions of the device while simultaneously providing low thermal resistance. Above a predetermined threshold temperature, the phase change material can change into a molten state and wet the joint surfaces to create a thin, low thermal resistance interface. The phase change material can be thixotropic and can be relatively viscous when in liquid form such that the material does not flow or otherwise migrate from the interface during operation.
