DF40C-100DS-0.4V(58) from Hirose Electric Co Ltd is a fine-pitch board-to-board mezzanine receptacle designed for compact electronic assemblies where space savings, signal density, and reliable interconnect performance are important. With 100 positions in a 2-row, 0.40 mm pitch format and surface-mount termination, it is well suited for portable devices, industrial control modules, embedded computing boards, display assemblies, and other high-density PCB stacking applications. Engineers typically choose this connector family when they need low-profile interconnection between parallel boards while maintaining precision alignment and compact mechanical packaging. Based on the provided product status, this part is listed as Active, which is generally favorable for ongoing design use. However, lifecycle monitoring is still recommended as supply conditions can change over time. RoHS compliance information is not available in the provided data, so designers and compliance teams should confirm the latest environmental status directly through the official datasheet, manufacturer documentation, or authorized sourcing channels before release to production.