DF40C-100DS-0.4V(51) from Hirose Electric Co Ltd is a fine-pitch rectangular board-to-board receptacle designed for compact electronic assemblies where connection density and low profile are critical. With 100 positions, 0.40 mm pitch, dual-row layout, and SMT mounting, it is well suited for mobile devices, portable instruments, industrial control modules, embedded computing boards, and other space-constrained designs that require reliable signal interconnection between stacked PCBs. The active product status supports its use in ongoing production, while the connector category generally aligns with longer market lifecycles than many semiconductor devices. Lifecycle status beyond the provided active listing is not separately confirmed, so engineers should still verify current manufacturer support for long-term programs. RoHS compliance information is not explicitly provided in the supplied specifications, so compliance should be treated as information not available pending official documentation. For regulated applications, buyers should confirm RoHS and related material declarations directly with Hirose or authorized distribution sources before release to production.