DF40HC(3.5)-80DS-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 high-density interconnection. With 80 positions, 0.40 mm pitch, dual-row configuration, and a 3.5 mm mated stacking height, it is well suited for portable devices, industrial control modules, communication equipment, embedded computing platforms, and other space-constrained PCB designs. Engineers typically choose this style of connector when signal routing density, low-profile assembly, and repeatable board stacking are important design priorities. The gold contact finish supports dependable mating performance in precision interconnect applications. Based on the provided data, the part is supplied in tape and reel and currently shows normal supply and demand status, which is favorable for ongoing procurement. Lifecycle status is listed as unknown, so designers should confirm long-term availability directly with Hirose or an authorized source before committing to new programs. RoHS compliance information is not available in the provided specifications and should be verified through official manufacturer documentation.