We present two different techniques for achieving low resistance (<20 n\(\Omega \)) contacts between copper and aluminium at cryogenic temperatures. The best method is based on gold plating of the surfaces in an e-beam evaporator immediately after Ar plasma etching in the same apparatus, yielding resistances as low as 3 n\(\Omega \) that are stable over time. The second approach involves inserting indium in the Al/Cu joint. For both methods, we believe key elements are surface polishing, total removal of the aluminum oxide surface layer, and temporary application of large (typ. 11 kN) compression forces. Such contacts are not demountable. We believe the values for gold plated contacts are the lowest ever reported for a Cu/Al joint of a few \(\mathrm{cm}^{2}\). This technology could simplify the construction of thermal links for advanced cryogenics applications, in particular that of extremely low resistance heat switches for nuclear demagnetization refrigerators.

我们介绍了两种不同的技术，可在低温下实现铜和铝之间的低电阻（<20 n （（Ω）））接触。最好的方法是基于在同一设备中进行Ar等离子刻蚀后立即在电子束蒸发器中进行表面镀金，从而产生低至3 nΩ （Ω）的电阻，该电阻随时间稳定。第二种方法涉及在Al / Cu接头中插入铟。对于这两种方法，我们认为关键因素是表面抛光，完全去除氧化铝表面层以及暂时施加较大的（通常为11 kN）压缩力。此类触点不可拆卸。我们认为，镀金触点的值是有史以来最低的，铜/铝接头中只有几个\（\ mathrm {cm} ^ {2} \）。这项技术可以简化用于高级低温应用的热链接的结构，特别是用于核退磁冰箱的极低电阻热开关的结构。