Thermal conductance of indium solder joints at low temperatures

The thermal conductances of two indium solder joints were measured between 2 and 130 K. One joint was between two copper pieces and the other joint between beryllium and copper. Both joints gave nearly the same results even though beryllium is much more difficult to wet with indium. The thermal conductances of the joints at 4 K were considerably higher than those of joints using alloy solders such as lead–tin. The maximum conductance per unit area was about 100 W/cm2 K, which occurred at about 20 K.