The Hirose DF40C-24DS-0.4V(51) is a 24-position receptacle with center strip contacts from the DF40 series, a family of fine-pitch board-to-board mezzanine connectors.
Position Count and Stack Height — Which Variant Fits Your Board
Within the DF40C sub-family, the 24-position DF40C-24DS-0.4V(51) sits between the 20-position DF40C-20DS-0.4V(51) and the 30-position DF40C-30DS-0.4V(51) at the same 0.40mm pitch and 1.5mm stack height — the choice is purely a circuit-count match. For a taller stack, the DF40C(2.0)-20DS-0.4V(51) lifts the mated height to 1.95mm while keeping the same 0.40mm pitch and 20 positions; that variant trades a lower profile for a slightly taller envelope if your board spacing allows.
The thin gold layer provides corrosion resistance on the mating surface without the cost of a heavy-gold deposit; it handles the few dozen cycles typical of a board-to-board mezzanine connection during assembly and rework. This is not a connector rated for repeated field disconnect or high-current power delivery — the 0.40mm pitch physically limits per-contact ampacity well below what the plating could sustain.