What this connector is
The Amphenol FCI 79821-140HLF is a 40-position dual-row board-to-board header in the BERGSTIK II series. It terminates via through-hole solder pins and uses a push-pull fastening type rather than the friction-fit typical of this pitch class — the retention mechanism is designed to hold the mated pair without jack-screws or latching hardware. Contacts are phosphor bronze with 30.0 µin (0.76 µm) gold plating on the mating interface, and the insulation body carries a UL94 V-0 flammability rating. The 0.100" (2.54 mm) pitch and 0.100" row spacing put this squarely in the classic dual-row footprint used across industrial control, instrumentation, and communications boards — the same grid that decades of legacy equipment were designed around.
Key ratings and what they mean
5 A per contact at 110 V: the voltage rating for this pitch is conservative relative to some higher-pitch families — 110 V is appropriate for signal and low-power distribution on the board stack rather than anything approaching mains or higher rail voltages. If the application sits near that ceiling, verify the working voltage against your creepage and clearance budget. 30.0 µin (0.76 µm) gold plating: at this thickness the contact finish supports significantly more reconnection cycles than a tin-plated or thin-flash gold part. For test-fixture or field-service applications where the header sees repeated mating, this is the primary cycle-life enabler — not the base contact material. All 40 positions are loaded — every site on the header is populated, so there is no partial-load option within this exact MPN. Insulation height of 0.100" (2.54 mm) sets the post-protrusion above the board surface and constrains what receptacle housing or wire-to-board plug can accept the post length without bottoming out. The post extends 0.200" (5.08 mm) below the board and 0.430" (10.92 mm) above it, giving a combined contact length of 0.730" (18.54 mm) — verify your mating half's pin-entry depth against this.
Where this connector is used
Board-to-board stacking and right-angle transition are the primary use cases for this style — the unshrouded header mates with the matching IDC receptacle or socket housing in the same series. The push-pull fastening is common in test-and-measurement equipment and in industrial modules where field technicians need to connect and disconnect the board stack without tools. The UL94 V-0 housing rating makes it suitable for equipment subject to UL or CE flammability requirements — a baseline material property rather than an IP sealing claim, since this is an unshrouded connector with no stated ingress protection.
Lifecycle and sourcing
Listed as Active. The 79821 is the base product number; the 40-position count is fixed in this exact MPN. A different position count in the same series footprint is the cross-reference candidate if the BOM requires a change. Sourced to order against BOM quantity — confirm position count against your board stack design before committing. The mating half (receptacle housing or IDC socket) is ordered separately; a mismatched housing will not accept the full post length without bottoming out.