0.35 mm Pitch, 0.6 mm Stack — BM28 Mezzanine Header
The Hirose BM28B0.6-50DP/2-0.35V(53) is a 50-position header from the BM28 series, a board-to-board mezzanine connector family built around a 0.014" (0.35 mm) pitch and a 0.6 mm mated stacking height. It uses a header with outer shroud contacts, arranged in two rows, and terminates via surface mount with solder retention features.
Pitch and Positioning
At 0.35 mm pitch, this is the finest contact spacing in the BM28 line. That pitch drives the PCB footprint — trace routing between pads is tight, and the mating receptacle must match the same 0.35 mm pitch. The 50 positions give 25 circuits per row, a count that sits between the 40-position (BM28B0.6-40DP/2-0.35V(53)) and 58-position (BM28B0.6-58DP/2-0.35V(53)) siblings in the same 0.6 mm stack height group. Choose the position count to match the signal I/O count on the BOM — no headroom for unused pins at this density.
Stack Height and Z-Budget
The 0.6 mm mated stacking height is the lowest option in the BM28 series. At 0.018" (0.46 mm) above the board, the header sits nearly flush with the PCB surface after reflow.
Contact Finish and Duty
That is a flash gold — adequate for the moderate mating cycle counts typical of internal device interconnects (50 to 100 cycles) in controlled indoor environments. For applications requiring high-cycle field service or exposure to corrosive atmospheres, a thicker gold finish on the mating half may be needed to maintain contact resistance stability.
No through-hole posts; alignment during placement relies on the solder-paste stencil and pick-and-place accuracy. The Tape & Reel packaging (Cut Tape option available) feeds directly into an SMT line.