0.40mm Pitch Mezzanine Receptacle for Tight Board Stacks
The Hirose DF40HC(3.0)-40DS-0.4V(51) is a 40-position receptacle from the DF40 series, designed for board-to-board mezzanine connections at a 0.40mm pitch. It uses a dual-row, center strip contact arrangement and surface-mount termination, with gold-plated contacts rated for repeated mating cycles.
Stack Height and Footprint Constraints
The 3mm mated stacking height is the single most important dimension for mechanical fit — it determines the clearance between boards in a mezzanine stack. At 0.40mm pitch, the trace escape from the inner rows requires micro-vias or blind vias in the pad; standard through-hole vias between pads won't fit without necking the trace width below the fab's tolerance. The 2.90mm height above board gives the component profile on the receptacle side, which matters for the keep-out zone on the opposite board.
Contact Plating and Mating Duty
Gold contact finish at 2.00µin thickness is a flash plating — adequate for the moderate mating cycle counts typical of internal board-to-board connections in consumer and portable devices. The gold layer prevents oxidation on the mating interface during storage and initial mating, but the thin deposit means the connector is not rated for frequent field-service disconnect cycles. The center strip contact geometry keeps the signal path short and the inductance low, which helps maintain signal integrity at the data rates this pitch class supports.