Part 20 - Plated gold edge connectors
Channel: Eurocircuits
Date: 2014-05-08

For edge-connectors we electroplate hard gold.  First the operator puts protective tape on the board above the connectors.  Then he mounts the panel on a horizontal electroplating bath.  Electroplated gold is needed for edge connectors on printed circuit boards which will require repeated insertion and removal..  Electroless gold gives good solderability but is too soft to withstand repeated abrasion.  For this you require a hard electroplated gold.  For edge connectors we electro-plate 1 -- 1.5 microns of gold over 4 -- 5 microns of plated nickel.  So if your PCB will be repeatedly inserted into a connector, you should specify hard gold plate on the edge connectors.

http://www.eurocircuits.com/index.php/making-a-pcb-eductional-movies/48-plated-gold-edge-connectors