Ultra-Compact 0.35 mm Pitch Header for High-Density Mezzanine Interconnects
The Hirose BM28B0.6-50DP/2-0.35V(51) is a 50-position, dual-row header from the BM28 series, designed for board-to-board mezzanine stacking where PCB real estate is at a premium. Its defining feature is the 0.014" (0.35 mm) pitch — one of the tightest in the Hirose lineup — which allows 50 signal lines to route through a footprint roughly the width of a grain of rice.
What the 0.35 mm Pitch and 0.6 mm Stack Height Mean for Your Layout
The 0.35 mm pitch drives the board layout more than any other spec. It dictates the receptacle's contact spacing and forces tight trace routing between pads — expect to work with 0.15 mm to 0.18 mm trace/space on the inner layers if you're running all 50 signals out. The 0.6 mm mated stack height is the total z-height from the host board top surface to the top of the mated receptacle; the header itself sits just 0.018" (0.46 mm) above the board, which leaves almost no clearance for components on the underside of the mezzanine board. The dual-row arrangement packs the 50 positions into a narrow body, but the outer shroud contacts mean the mating receptacle must align precisely — there's no floating contact beam to compensate for misregistration.