Design and testing results of a long flexible printed circuit for the ATLAS high granularity timing detector

The high granularity timing detector for the ATLAS upgrade is under construction to meet the challenges of the HL-LHC. The silicon detectors along with the electronics are installed in two double-sided disks per end-cap and consist of basic units (called modules) connected to the peripheral electronics by flexible printed circuit cables. The complexity of the system impacts on the requirements of having high number of interconnections for the power delivery network, the data-links for the high-speed readout as well as the inputs for the system control. This and other constraints on the topology, the reduced space between disks and mechanical robustness led to the development of a flexible printed circuit cable. We present the design and test of a two-layer flexible cable of a maximum connection distance for the module.