X-IFU Focal Plane Assembly Development Model design upgrade and critical technology developments

This paper describes the redesign performed on the X ray Integral Field Unit Focal Plane Assembly (X-IFU FPA) Development Model (DM) in preparation of the instrument PDR and MAR, with a focus on the mechanical modifications of the T0 detector stage. A new, flight sized detector is used, as well as flight scalable interconnections to route the TDM signals to the MUX chip and subsequent cold electronics. In addition the development of several critical technologies within the DM1.1 are described. These include fixation of the main TES array to the metal support, a dedicated wire bonding process of the main TES array to the side panel MUX carrier chips and interconnection of the super-conducting Nb flex cables to the connecting Printed Circuit Boards (PCB).