Front-end hybrids for the strip-strip modules of the CMS Outer Tracker Upgrade

The CMS Outer Tracker planned for the HL-LHC Upgrade contains strip-strip and pixel-strip silicon modules. Each of them includes two high-density front-end hybrid circuits, equipped with flip-chip ASICs, passives, connectors and mechanical structures. Several strip-strip hybrid prototypes have been produced using the CBC2 front-end ASIC. Feedback from these developments helped improving the hybrid's testability and the production yield. The availability of the concentrator ASIC's footprint and of the new CBC3 front-end ASIC enables the design of all strip-strip hybrid variants. In this work, the development milestones and the final designs are presented together with chosen solutions.