The Amphenol FCI 93939-454HLF is a 54-position, dual-row BERGSTIK® II unshrouded header with a 0.100" (2.54mm) pitch — the standard grid for legacy and cost-sensitive board-to-board interconnects. All 54 positions are loaded, so the footprint matches the circuit count one-to-one.
Tin plating and mating cycles
The 100.0µin (2.54µm) tin finish on the mating surface is a heavy-duty layer — thicker than the typical 30-50µin flash tin found on commodity headers. For a header that mates once in assembly and stays connected, the tin plating keeps the per-unit cost down while delivering adequate contact resistance over the product life.
Board layout and footprint
The 0.100" row spacing matches the mating pitch, so the PCB footprint is a straightforward 2 x 27 grid of 0.040" square pins. The 0.120" (3.05mm) post length after the board surface gives enough solder tail for a standard 0.062" PCB with through-hole wave soldering.
The BERGSTIK® II series is a broad, multi-sourced platform, so alternate pin counts and plating options exist within the same footprint family if a BOM revision is needed.