Flexible Printed Circuit design and testing for the High-Granulary Timing Detector for the Phase II upgrade of the ATLAS calorimeter system

The High-Granularity Timing Detector (HGTD) will improve the performance of the ATLAS detector for the Phase II upgrade of the HL-LHC by providing precise timing information. The basic unit detector consits of a hybrid module of a 2 cm x 4 cm Low Gain Avalanche Detector (LGAD) bump-bonded to two ASICs and wire-bonded to a Flexible Printed Circuit (FLEX cable). The latter transmits high-speed signals (1.28 Gbps) for data readout while providing power and HV to the module. Its design mul fulfil the HGTD requirements both mechanically and electrically, combining different signal types. The design and the testing plan of the initial prototype are presented.