DF40C(2.0)-50DS-0.4V(51) from Hirose Electric Co Ltd is a fine-pitch board-to-board mezzanine receptacle designed for compact electronic assemblies that need reliable interconnect density in limited PCB space. With a 0.40 mm pitch, 50 positions, 2-row layout, and 2 mm mated stacking height, it is well suited for portable devices, industrial control modules, embedded computing boards, imaging equipment, and other space-constrained designs where low-profile signal routing is important. Its surface-mount format and gold contact finish support stable mating performance for precision applications. Within the Connectors, Interconnects > Rectangular - Board to Board Connectors - Arrays, Edge Type, Mezzanine category, this part fits designs that prioritize miniaturization and board stacking efficiency. Lifecycle status is currently listed as information not available, so engineers should confirm ongoing production directly with Hirose or authorized sources before committing to long-term programs. RoHS compliance information is also not explicitly provided in the available data and should be verified through official manufacturer documentation.