Electrical resistance measurements at 4.2 K have been made for various screw-fastened thermal joints used at ultra-low temperatures below 100 μK. The measured contact resistance for a gold-plated joint varied in inverse proportion to a tightening torque of the screw. With a maximum tightening torque for a 4-mm stainless-steel screw, several types of the joints revealed to have contact resistances below 10 nΩ. A current-decay method used to measure a small variation of contact resistance of less than 0.1 nΩ is also described.
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Okamoto et al. (1990) studied this question.