Hexaboard Visual Inspection Pipeline for the CMS High Granularity Calorimeter

The Compact Muon Solenoid (CMS) is an experiment at the Large Hadron Collider at CERN. In the near future, CMS will incorporate the High Granularity Calorimeter (HGCAL) as a major upgrade to its detector system. HGCAL will be constructed modularly from many hexagonal-shaped computer boards (hexaboards) attached to silicon sensors. For this, many thousands of hexaboards will need to be tested for quality. One such test is visual inspection to ensure quality of wire bonding, no glue leakage, and no damaged or missing components. Performing these inspections manually requires expertise, expensive equipment, and time. To accelerate this task, we introduce a hardware and software solution. For the hardware solution, we developed a rail-mounted camera system to capture images of the hexaboards. Those images of the hexaboards are then processed and analyzed to flag potential defects. This solution is automated, efficient, and produces high-quality scans comparable with systems on the order of 20 to 100 times more expensive.