DF40C-90DS-0.4V(51) from Hirose Electric Co Ltd is a surface-mount rectangular connector receptacle in the DF40 family, designed for compact board-to-board interconnect applications where high contact density and reliable mating performance are important. With 90 positions and gold-plated center strip contacts noted in the provided specifications, it fits space-constrained designs such as industrial control modules, portable electronics, embedded computing platforms, and communication equipment. For engineers selecting interconnects in the Connectors, Interconnects > Rectangular Connectors category, this part is positioned as a fine-pitch SMT solution for dense PCB layouts and automated assembly. Lifecycle status is currently listed as unknown, so teams should assess long-term design risk carefully, especially since supply and demand status is marked limited and estimated production lead time is 25 weeks. REACH status is listed as unaffected, but RoHS compliance information is not explicitly available in the provided data; engineers should confirm current RoHS status directly with Hirose documentation before release.