Board-to-Board Mezzanine Plug for Tight Stack Heights
The Molex 5055514020 is a 40-position plug from the SlimStack 505551 series, designed for parallel board-to-board mezzanine connections. With a 0.016" (0.40mm) pitch and a mated stacking height of 0.8mm, this connector is built for dense, low-profile interconnects where board spacing is at a premium.
What the 0.40mm Pitch and 0.8mm Stack Height Mean for Your Layout
The 0.8mm mated stack height is the key dimension for the z-axis budget: it sets the gap between the two PCBs, so the mating receptacle (the 505551 series receptacle, same pitch and row count) must be paired to achieve this height. The two-row, 40-position layout gives 20 contacts per row, which is a dense signal count for a board edge that measures roughly 8mm along the mating axis.
On a part this small (0.68mm above board), the retention tabs prevent tombstoning and keep the connector aligned through the solder paste reflow cycle. The surface mount termination suits standard pick-and-place assembly; the Tape & Reel packaging (Cut Tape option also available) feeds directly into the feeder.
Mating Connector and Compatibility
The 5055514020 mates with the matching SlimStack 505551 series receptacle — the same 40-position, 2-row, 0.40mm pitch configuration. The receptacle is the female half with the same outer shroud design, ensuring the plug's contacts are protected during mating. There is no official cross-reference or replacement on record; the 505551 series is the current active line for this form factor. If you need a different stack height, the SlimStack family includes other members with varying heights, but the pitch and contact arrangement are series-specific.