The Hirose DF37NB-70DS-0.4V(51) is a 70-position receptacle from the DF37 series, using center strip contacts on a 0.40mm pitch across two rows.
What the 0.40mm pitch and 70 positions mean for your board
The 0.40mm pitch is the tightest in the DF37 line — it drives the PCB fab capability needed: standard 0.5mm-pitch routing rules don't apply here. You'll need controlled impedance traces and via-in-pad or microvia escape routing for the inner rows. The 70 positions make this the highest circuit-count member of the DF37 series; against the 50-position DF37NB-50DS-0.4V(53) or the 40-position DF37NB-40DS-0.4V(51), the only meaningful difference is position count. Pitch, height, contact finish, and mounting are identical across all three, so the selection comes down to matching the exact circuit count on your BOM line.
Mating and stacking
The mated stack height of 0.98mm means the board-to-board gap is fixed at just under a millimeter; there's no adjustment. The SMT pads and solder retention features are designed for standard reflow profiles, and the gold-on-gold contact interface keeps resistance stable through the rated mating cycles. The connector is keyed by its center strip contact geometry — it only mates one way, so you won't reverse the stack.
It's RoHS Compliant per, so it meets the material restrictions for EU-market equipment.