Electrical Qualification of the Pre-production of Analogue Opto-Hybrid Circuits for the CMS Tracker Inner Barrel and Inner Disks.

A pre-production of 50 analogue opto-hybrid (AOH) circuits to be used in the front-end electronics of the CMS tracker was extensively tested before the incoming start of the massive production. A total of 4000 AOHs are required for the tracker inner barrel (TIB) and inner disk (TID) construction. The electrical response of the TIB/TID AOH pre-production was tested at 25°C both for the static and dynamic behavior. A subset of five AOHs was cooled and tested at -10°C and -15°C. A passive thermal cycle test from -20°C to 25°C was done on a sample of 22 pre-production AOHs, including the previous subset, to measure the mechanical response at possible variations of the nominal tracker temperature of -10°C. Four AOHs from the subset were also kept at -15°C for 20 hours in order to check the long-term stability of the response. The measurements were obtained with the automatic test equip ment (ATE) built for the fast qualification during the massive AOH production and with a custom setup dedicated to the additional tests foreseen only in the pre-production phase. Results of the tests at 25°C are reported and show the very good agreement with the specifications required for the AOH circuit. No mechanical stress, nor electrical response variations were observed after the passive thermal cycles and the AOH behavior at low temperature was also very good and stable.