The PCB surface bond gold is a collective term for bonding-capable surfaces, usually a gold surface (see bonding). For bonding are applied: immersion gold (ENIG, reductively) for bonding aluminum wire (Al), electroplated soft gold for bonding gold wire (Au) and ENEPIG (Electroless Nickel Electroless Palladium Immersion Gold), which is suitable for both bonding methods.
The thickness of the gold layer is with chemical (immersion) bond gold about 0.3-0.6µm, with electroplated (soft-) bond gold about 1.0-2.0µm and about 0.05-0.1µm gold plus 0.05-0.15µm palladium for ENEPIG. The gold layers are based on approximately 3.0-6.0µm nickel (see printed circuit board surfaces).
As bonding surface (bond gold), we recommend ENEPIGGlossary because this surface is all-purpose and very stable. Please speak in doubt always with your assembly partner!