90-Position, 0.40mm Pitch Mezzanine Receptacle
The Hirose DF40HC(4.0)-90DS-0.4V(51) is a 90-position receptacle from the DF40 series, designed for board-to-board mezzanine stacking. The SMT termination suits automated pick-and-place assembly.
4mm Stack Height — Board Spacing Constraint
This is a fixed value for this variant — the DF40 series offers other heights (3mm, 4.5mm) through different suffix codes. If your enclosure or module height budget is tighter than 4mm, check the DF40 family for a lower-profile option.
Position Count vs. Siblings
At 90 positions, this is a high-density member of the DF40 series. If your BOM calls for 80 signals, that part saves 10 positions of board area; if you need 90, this is the one.