Board-to-Board Mezzanine Fit — 0.35mm Pitch, 0.8mm Stack
The Hirose BM23PF0.8-42DS-0.35V(895) is a 42-position receptacle with center strip contacts from the BM23 series, designed for board-to-board mezzanine stacking where the z-height budget is tight. The 0.014" (0.35mm) pitch and 0.031" (0.80mm) height above board set the mated stack height at 0.8mm — that is the clearance from one PCB to the other once the mating plug is engaged.
The BM23PF0.8-42DS-0.35V(895) sits between the 40-position BM23PF0.8-40DS-0.35V(895) and the 46-position BM23PF0.8-46DS-0.35V(895) in the same BM23 family. All three share the 0.35mm pitch, 0.8mm stacking height, gold plating, and solder retention. The choice comes down to the signal count on the board — 42 circuits match the BOM line exactly; the 40-position variant is the closest drop-in for a lower channel count, while the 46-position version adds four more lines without changing the footprint pitch. No other spec differences exist between these three — the footprint length scales with the position count.