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.