Plating Hard Gold onto printed circuit boards is typically done to provide contact points and PCB edge connectors.
Gold contact surfaces are often used on circuit boards with membrane switches which are a technology of choice for industrial, commercial and consumer products. When PCBs will be repeatedly installed and removed, electroplated gold is used for edge-connector contacts or as they are more commonly known: Gold fingers. The plating thickness of a PCB gold finger is typically a mere 300 micro-inch. At this thickness the hard gold is expected to survive 1,000 cycles before wear through.