Design Engineering Note: 54-Position Unshrouded Header
The FCI 79821-454HLF is a 54-position, dual-row unshrouded header from the BERGSTIK® II series, designed for board-to-board interconnects. With a 0.100" (2.54 mm) pitch and matching row spacing, it follows the standard 0.100-inch grid that dominates prototyping and production PCB layouts. Rated for 5 A per contact, the current capacity is typical for this pitch class — adequate for signal and moderate power distribution. The tin-on-tin contact interface (100.0 µin mating finish) is a cost-optimized choice for applications with limited mating cycles, such as internal board stacking or permanent harness connections.
Footprint and Fit
Through-hole termination with a 0.200" (5.08 mm) post length provides a solid mechanical anchor into the PCB. The overall contact length of 0.730" (18.54 mm) and mating length of 0.430" (10.92 mm) define the stack height when mated with a compatible receptacle. The unshrouded design means the pins are exposed after mating — no polarization or keying, so the mating half must be aligned by the board layout or a separate alignment feature. The push-pull fastening type relies entirely on contact friction for retention; vibration-sensitive assemblies may need additional mechanical support.