Since early 1990s the alloy surface (nickel / phosphorus & gold) is one of the most versatile surfaces. In this method, a nickel layer forms the diffusion barrier between copper and solder alloy. The gold is dissolved in the solder joint and the liability / IMC formation is done with the nickel layer. Electroless nickel-gold requires an upstream copper activation to start the nickel deposition. The nickel layer increases mechanical vias and increases the abrasion resistance.

Not every surface is equally suitable for every use.

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.