Factory Acceptance Test for Serenity-S1, a CMS Phase-2 back-end card

Abstract

The CMS Phase-2 upgrade for the High-Luminosity LHC requires the replacement of the back-end electronics in several sub-detectors. For this purpose, the Serenity consortium has developed Serenity-S1, a versatile ATCA-based FPGA processing card adopted by seven CMS sub-detector systems. With a total production of more than 700 boards, an efficient and reliable quality-assurance process is essential. This paper presents the Factory Acceptance Test (FAT), an automated test system that extends the assembly and electrical integrity checks performed by the PCB manufacturer and assembler, enabling comprehensive functional testing of each board directly at the production site in less than ten minutes. The FAT leverages on-board controllers and existing board-control frameworks, integrating them into a Python-based Pytest environment to structure and sequence test runs. A dedicated test PC runs the control software that orchestrates the test system, generates detailed reports with database upload, and offers two intuitive graphical interfaces for visualising the results. Experience from using the FAT during pre-series production demonstrates its capability to enable early fault detection, short repair cycles, and consistent board quality across multiple test sites.