The Hirose BM20B(0.8)-34DS-0.4V(51) is a 34-position receptacle with center strip contacts, part of the BM20 series of fine-pitch board-to-FPC mezzanine connectors. At a 0.016" (0.40mm) pitch and a mated stacking height of 0.031" (0.80mm), it sits in the ultra-low-profile segment of the series — designed for parallel PCB stacking where the z-height budget is under a millimeter. The gold-plated contacts and dual-row layout suit signal-density applications in compact portable electronics, camera modules, and display interconnects where the FPC is installed once and rarely re-mated.
Pitch and Board Footprint
The dual-row layout packs 34 circuits into a body roughly 7.5 mm wide, so the keep-out zone on the board is narrow enough to route traces under the connector on inner layers.
Mated Stack Height and Z-Axis Clearance
The 0.80mm mated stack height — listed as both 0.031" and 0.8mm — is the total z-height from the mounting board surface to the top of the mated FPC. That leaves no room for components on the opposing board under the connector footprint. The opposing board must have a bare keep-out zone or a thin PCB stack to avoid mechanical interference. For a 0.8mm mated height, the typical PCB thickness on each side is 0.6mm or thinner, keeping the total assembly under 2.0 mm.
The gold contact finish thickness is 2.00µin (0.051µm). For repeated reconnection, consider variants with thicker gold.