Future of the next camera onboard space observatories implies a major enhancement in number of pixelsand a very low operative temperature (below 0.1 K). In this evolution, the large number of output wiresfrom the cool detector is often responsible of the most important thermal load onto the cold bath(cryostat).In this context, the thermal insulation between the different detection circuits is the bottleneck for thesecameras. An innovative technological component, protected by a patent, has been developed to tackle thisproblem. This device has both an excellent electrical resistivity and a very high thermal resistivity.The proposed solution is a stack of thin superconducting layers at electrical interconnections.The thermal resistance at each interface relies on the elastic properties of the materials used, the quality ofthe interfaces and temperature. The AMM model used in conjunction with the measured materialcharacteristics allows a theorical estimation of the thermal resistance per interface. The measurementsundertaken with superconducting connections with very high thermal resistivity are very well describedby this AMM model. We have measured thermal resistances as high as 3.3 105 K/W @ 200 mKfor a multilayer of 62 interfaces built with titaniun nitride and niobium alternatively on a 16 mm2 array.In the conditions foreseen for a 4000 micro-calorimeters camera operating at 50 mK in X-rays,this multilayer technique should allow a thermal load onto the cold bath that is much lower that 1 mWfor more than 8000 contacts.
microcalorimètre,rayonnement X,Conductivité thermique aux interfaces,diaphonie,basses températures,