Thermal boundary resistance of mechanical contacts between solids at sub-ambient temperatures

The experimental values of the thermal boundary resistance occurring at interfaces between two solids at sub-ambient temperatures are reviewed. New data are presented in the temperature range from 4 K to 300 K for the thermal resistance between different metals (Cu, stainless steel), interlayered by various cryogenic bonding agents (Apiezon-N, Cryocon grease, In and InGa), or mechanically connected (dry) contacts. Depending on the contact materials, the thermal conductance varies between and at room temperature, and decreases approximately linearly by one order of magnitude between 200 K and 20 K. Our experimental data agree well with the data reported in the literature for the temperature range below 4 K and measurements near room temperature.