DF40HC(3.5)-30DS-0.4V(58) from Hirose Electric Co Ltd is a 30-position board-to-board mezzanine receptacle designed for compact electronic assemblies that need fine-pitch interconnect density and reliable surface-mount integration. With a 0.40 mm pitch, 2-row layout, and 3.5 mm mated stacking height, it is well suited for space-constrained products such as portable devices, industrial control modules, embedded computing boards, display interfaces, and communication equipment. Gold contact finish supports stable signal transfer and dependable mating performance in designs where connector reliability matters. Based on the provided specifications, the part is listed as Active, which is a positive indicator for ongoing design use, although long-term lifecycle planning should still be verified through the manufacturer. RoHS compliance information is not explicitly provided in the supplied data, so engineers and procurement teams should confirm current RoHS and any related REACH status using official Hirose documentation before release to production or regulated markets.