The End-of-Substructure card for the ATLAS ITk Strip Upgrade: Lessons learned from the full production

The ATLAS Strip Tracker for HL-LHC consists of so-called modules that host the silicon sensors and the front-end electronics. These units are then mounted on mechanical structures, the so-called staves and petals, which are hosting up to 14 modules per side. An End-of-Substructure (EoS) card connects up to 28 data lines from the modules to and up to 12 lines from the lpGBT ASIC. The lpGBT then does (De-)Serialization and connects to the VL+ ASICs which then provides a 10 GBit/s optical data transmission to the off-detector systems respectively. The EoS is powered by a dedicated Dual-Stage DC-DC converter unit. As the both staves and petals host modules on both sides, two EoS are required for each stave and petal, however to reduce cabling, they are sharing a single voltage connector. While schematically the EoS cards are very closely related, especially for the barrel each layer requires a distinct layout, which adds complexity also for testing. As the EoS production of almost 2000 EoS cards and the accompanying 2000 DC-DC converters is going to be completed in fall 2024, we report on the production experience including detailed QC statistics. We conclude with a few lessons learned during the project duration.