0.50 mm Pitch Mezzanine Header, 40 Positions, 5 mm Stack
The Hirose DF12D(5.0)-40DP-0.5V(81) is a 40-position header from the DF12 series, designed for board-to-board mezzanine stacking. The connector is surface-mount and includes an integrated board guide to help locate the mating receptacle during assembly.
Hirose has marked the DF12D(5.0)-40DP-0.5V(81) as Obsolete. This means the factory no longer manufactures it as a standard catalog item.
The 0.50 mm pitch drives the PCB footprint: each signal pad sits on a 0.50 mm grid, which limits trace escape width between pads to roughly 0.20 mm on outer layers with standard PCB fab capabilities. The 5 mm mated stack height sets the standoff between the two boards — check that the mating receptacle (the DF12 series receptacle half) also specifies a 5 mm stack height to achieve the correct mated dimension. The board guide feature adds a pair of alignment posts that engage before the contacts, reducing the risk of stubbing the fine-pitch terminals during manual or automated assembly.
Contact Finish and Duty
The outer shroud contacts provide a ground-return path and some EMI containment around the signal pins, though the primary signal integrity benefit is the controlled impedance environment the shroud creates between the two boards.