What the 0.60mm pitch and 140 positions mean for your board layout
The Hirose FX8C-140P-SV6(91) is a 140-position header from the FunctionMax™ FX8C series, built for high-density board-to-board mezzanine stacking. The 0.024" (0.60mm) pitch packs 140 circuits into a dual-row footprint that demands careful routing — the trace escape under the header needs micro-vias or tight neck-downs on inner layers. Gold-plated outer shroud contacts protect the signal pins during blind mating; the shroud takes the initial alignment hit so the 0.60mm-pitch contacts don't get bent on engagement. The 10.85mm board height (0.427") supports mated stacking heights of 11mm and 16mm, depending on the receptacle height selected. This is a surface-mount part (SMT), shipped in tube packaging, with a board guide feature to assist alignment during reflow assembly.
Stacking height selection — matching the receptacle to the gap
The FX8C-140P-SV6(91) sits at 10.85mm above the board. When mated with the correct FunctionMax™ FX8C receptacle, it achieves a mated stack height of 11mm or 16mm — the receptacle's own board height determines which. For a 11mm total gap, the receptacle must sit at roughly 0.15mm above its board; for 16mm, the receptacle height is about 5.15mm. The board guide on this header helps keep the two halves aligned during assembly, which matters when the 0.60mm pitch leaves little room for misregistration.
How the SV6 compares to the other 140-position height variants
The FX8C series offers four 140-position headers at different board heights, all sharing the same 0.60mm pitch, gold plating, and SMT footprint. The SV6 (10.85mm) is the tallest; the SV4 (8.45mm), SV2 (6.45mm), and SV1 (5.45mm) step down in 2mm increments. The footprint and pinout are identical across all four — the only variable is the standoff height, which changes the mated stack height with the matching receptacle. Pick the SV6 when the board-to-board gap needs the full 11mm or 16mm; for tighter enclosures, the SV1 at 5.45mm saves 5.4mm of z-height.