The TE Connectivity 5-1735480-6 is a 140-position receptacle from the Free Height (FH) series, built for parallel board-to-board mezzanine stacking. At 0.031" (0.80mm) pitch and a 17mm mated stack height, it connects two PCBs at a fixed gap — think line cards to backplanes, or processor modules to baseboards where you need dense signal routing through a tall, air-gapped interface.
What the 17mm stack height and 0.80mm pitch mean for your board layout
The 0.80mm pitch is tight enough that you'll need a 4- or 6-layer PCB to route all 140 signals out from under the connector without resorting to blind vias. Check your enclosure's z-height budget before committing; this is not a low-profile mezzanine.
Gold contacts and surface-mount termination
The SMT tails reflow onto the board pads; there's no through-hole to solder, so you get a clean bottom-side without protruding leads.
It is ROHS3 compliant.