The Amphenol FCI 93939-428HLF is the 28-circuit member of the BERGSTIK II board-to-board header series. It mates with the matching BERGSTIK II female receptacle and is populated across both rows at the full position count — all 28 contacts are loaded. The dual-row layout at 0.100 inch row spacing sits at the same pitch as standard 0.050-inch-centre ribbon cable, so the header pairs cleanly with IDC sokets in harness-assemblies that run from board to board. Rated 5 A per contact at 110 V, the 93939-428HLF carries tin plating on both the mating interface and the solder tail — 2.54 µm (100 µin) thick on the mating face — which governs long-term contact resistance and solder-wetability on the through-hole post. The housing is UL94 V-0 rated and the push-pull fastening type refers to the header's friction-fit engagement with the mating receptacle, not a separate mechanical lock. The insulation stands 0.190 inch above the board surface when mounted.
What the ratings mean for selection
Pitch and footprint: 0.100 inch (2.54 mm) on 0.100 inch row spacing gives a two-column grid — the most common low-density board-to-board footprint in industrial control and instrumentation. The right-angle orientation mounts parallel to the daughter board edge, so it consumes board depth but leaves the mating face perpendicular for a perpendicular daughter-card entry. Current: 5 A per circuit is the per-contact headline. With both rows carrying signal or light-power circuits, the header suits applications where circuit count — not power density — is the primary driver. Voltage: 110 V is modest relative to the pitch — the spacing limits voltage before current does in high-voltage instrumentation. Applications above 100 V board-level should verify creepage on the specific board layout, not just the connector rating. Contact finish: Thick tin on both mating and post surfaces. There is no gold-plated variant of this specific order code — if the application requires gold for frequent mating cycles or elevated signal integrity, the BERGSTIK II gold-plated options in the same series must be evaluated separately. Termination: Through-hole solder posts at 0.120 inch (3.05 mm) post length and 0.160 inch (4.06 mm) mating-side engagement length give solid mechanical anchoring in FR4 or composite board. The square pin shape suits wave or reflow solder but does not self-align in the same way a round press-fit tail would.