0.35mm Pitch, 0.6mm Stack — the BM29 Header for Ultra-Thin Assemblies
The Hirose BM29B-2DP/2-0.35V(53) is a 4-position (2 + 2 Power) header from the BM29 series, designed for board-to-FPC stacking in tight z-height budgets. Its 0.014" (0.35mm) pitch packs signal and power into a dual-row footprint, while the 0.6mm mated stack height keeps the overall assembly thin enough for handheld or embedded modules. Gold-plated outer shroud contacts mate with the matching BM29 receptacle, and the 0.016" (0.41mm) height above board leaves clearance under the flex circuit.
Why the 0.35mm Pitch Drives the Board Layout
At 0.35mm pitch, the trace escape from each pad is tight — expect micro-via or fine-line routing between pads. The 2-row arrangement doubles the density per linear mm of board edge, but the 0.35mm spacing means the footprint is not forgiving of misregistration in the solder paste stencil. Gold plating on the contacts handles the low-insertion-force mating cycles typical of FPC interconnects, where tin fretting would be a risk over repeated flex.
4 Positions — Two Signal, Two Power
The 4 positions are split as 2 signal and 2 power contacts, a common arrangement for powering a small sensor or display module while passing a differential pair. The outer shroud contacts provide mechanical alignment and shielding continuity when mated with the BM29 receptacle. No current rating is listed in the spec table, but the gold finish and fine pitch suggest per-contact current in the sub-1A range — treat the power pair as a low-current bus, not a main rail.
No last-time-buy or phase-out notice has been issued.