DF37NC(1.5)-40DS-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, 40 positions, dual-row layout, surface-mount termination, and 1.5 mm mated stacking height, it is well suited for portable devices, embedded modules, industrial controls, communication hardware, and other space-constrained designs. Engineers typically select this connector family when low-profile stacking, stable contact performance, and precise board alignment are important. Based on the provided supply and demand status, market availability appears normal, supporting ongoing procurement planning. Lifecycle status is currently listed as unknown, so design teams should confirm current manufacturer status before committing to long-term programs. RoHS compliance information is not available in the provided data. Because this is a modern board-to-board connector category commonly used in global electronics, engineers should verify RoHS and any REACH declarations directly from Hirose documentation before release to production.