DF40HC(2.5)-40DS-0.4V(51) from Hirose Electric Co Ltd is a fine-pitch board-to-board mezzanine receptacle designed for compact electronic assemblies where space, stack height, and connection density are critical. With 40 positions, 0.40 mm pitch, dual-row layout, and a 2.5 mm mated stacking height, it is well suited for portable devices, industrial control modules, embedded computing boards, medical electronics, and other high-density interconnect designs. The gold contact finish supports reliable signal transfer in applications that require stable mating performance in compact form factors. Based on its connector category, this part fits designs that prioritize miniaturization and precise board alignment. Lifecycle status is currently listed as information not available, so engineers should confirm product status directly with Hirose or the latest authorized channel data before locking it into new designs. RoHS compliance information is also not available in the provided data, and compliance should be verified through official manufacturer documentation before procurement for regulated markets.