Controlled Impedance Termination for High-Density Multicoax Assemblies in Cryogenic Environments: Mitigating Thermal Contraction

As quantum computing systems scale up and qubit counts must increase to achieve practical quantum computing, integrators have favored solderless ganged coaxial approaches. However, departing from traditional SMA coaxial technology to the planar design of solderless ganged coaxial solutions risks electrical performance degradation due to coaxial cable expansion and contraction through thermal cycles. TR Cryo (TRC), Amphenol Ardent Concepts’ (AAC) iteration on a high density multicoax solution for cryogenic temperatures, was born from a need for greater mechanical stability at near absolute zero temperatures while maintaining strong signal integrity performance without sacrificing density. Thermal contraction is inevitable when cooling a system from room temperature down to near absolute zero, and to battle this inspiration can be taken from traditional SMA coaxial connectors. The back (and front of the female connector) allows for axial slippage of the mating coaxial center conductor and the fingers relative to the cylindrical geometry of the connector. This concept has been adapted for use in the TRC, allowing for internal slippage without loss of connection due to thermal changes. This presentation will share failure analysis data, SolidWORKS simulations, Ansys HFSS signal integrity analysis, and direct measurement correlation at >4K.