The nickel-gold plating-surface is abrasion-resistant and corrosion free and therefore it is often used for components with increased mechanical stress (male).
The resist coated circuit board is first provided with an electroplated nickel layer> 3μm as a diffusion barrier (preventing that the subsequent gold gradually "disappears" by diffusion). After the nickel plating followes by the actual galvanic golding. Gold layer between > 0.4μm to 2μm are deposited. This depends of the purpose. For plugs the number of jacking cycles is applied.
0,4 μm: 20 jacking cycles
0,7 μm: 50 jacking cycles
1,3 μm: 200 jacking cycles
2,0 μm: 500 jacking cycles