Board-Stacking Receptacle for Tight Z-Height Budgets
The Hirose BM20B(0.6)-20DS-0.4V(53) is a 20-position receptacle from the BM20 series, designed for board-to-board or FPC-to-board stacking where the vertical gap is at a premium. Its 0.016" (0.40mm) pitch and dual-row layout pack 20 circuits into a compact footprint, while the 0.6mm mated stacking height — stated directly in the order code — sets the clearance between parallel PCBs.
What the 0.6mm Stack Height Means for Your Assembly
The 0.6mm mated stack height is the defining dimension for this connector — it dictates the gap between the two boards or between a board and an FPC. At that height, the connector sits nearly flush, so the design must account for component keep-outs on the opposing board. The 0.024" (0.61mm) height above board tells you how much the receptacle itself stands off the PCB before mating; the mating half (a male header or FPC plug from the same BM20 series) fills the rest of the gap.
This is not a high-cycle field-service connector; the gold layer protects the base metal during the first few mates and then the contact relies on the underlying nickel barrier. For designs requiring repeated reconnection, consider a thicker gold option in the BM20 family, if available.