What this connector is
The Amphenol FCI 78511-117HLF is the 17-position member of the BERGSTIK II unshrouded male header series — a single-row 0.100 inch (2.54 mm) pitch board-to-board stacking header. The push-pull male pin is phosphor bronze with 30.0 µin (0.76 µm) gold plating on the mating face and an 0.318 inch (8.08 mm) mating length that gives the contact beam enough engagement to survive vibration without a locking shroud. The LCP insulator is rated UL94 V-0 and operates from -65 to 125 °C, so it holds up in industrial and automotive environments where the thermal cycling would crack a lesser housing material.
How the ratings drive the fit
The 5 A per circuit current rating at 110 V is the key number for power or mixed-signal board-to-board use — at 2.54 mm pitch the contact density is moderate, so the rating is contact-limited rather than thermally limited. The 30.0 µin gold plating over bronze gives the contact wear life needed for the push-pull mating style; if this were a tin-plated variant the reconnection count would drop significantly. The 0.100 inch insulation height sits at the same dimension as the pitch, which means in a dual-row stacking arrangement the board planners need to confirm the z-height budget clears the connector shoulder before committing.