DF37NC-20DS-0.4V(53) from Hirose Electric Co Ltd is a fine-pitch rectangular board-to-board receptacle designed for compact electronic assemblies where low profile and reliable interconnect performance matter. As part of the DF37 series, it is suited for space-constrained products such as portable devices, embedded control boards, industrial modules, medical electronics, and other high-density PCB stacking applications. Engineers typically select this type of connector for its 0.40 mm pitch, SMT mounting format, gold contact finish, and mezzanine-style architecture that supports dense layouts and stable signal paths in small form factors. Lifecycle status for this part is currently listed as unknown, so design teams should confirm long-term availability directly with Hirose or an authorized source before locking it into new programs. RoHS compliance information is not explicitly provided in the supplied specifications, so compliance should be treated as information not available pending official manufacturer documentation. For regulated builds, engineers should verify current RoHS and REACH declarations before procurement.