Thermal contact resistance of electrical insulation material at broad temperature and contact pressure

The current lead is an essential component for delivering current to the superconducting devices, and its performance affects the devices’ stability and performance. Enhancing the current lead’s performance necessitates high electrical insulation and low thermal contact resistance (TCR) at the joint with the cryocooler. Therefore, measuring the TCR of electrically insulated joints is necessary under actual conditions. A specimen holder is designed and fabricated to control contact pressure and temperature, and accurately measure heat flow. AlN, Al2O3, and Kapton film, common materials for electrically insulated joints, were chosen for the measurement. The TCR of each specimen increases as the temperature and contact pressure decrease. When providing the same electrical insulation ability, the TCR of AlN and Al2O3 was up to 25 times smaller than that of Kapton film.