Hard Gold PCB: including Full Body and Selective Hard Gold Plating
The Hard Gold surface finish, also known as Hard Electrolytic Gold, is composed of a layer of gold with added hardeners for increased durability, plated over a barrier coat of nickel using an electrolytic process. Hard gold is extremely durable, so during PCB Fabrication this finish is usually applied to high-wear areas, such as edge connector Gold Fingers and keypads, since the hardness of the finish can withstand repeated use; however, due to the high cost of hard gold, and its relatively poor solder-ability, it is very rarely applied to solder-able areas.
Full Body Hard Gold is generally a rarely-chosen surface finish, where the full body of the PCB board is plated with hard gold. In order to apply a Full Body Hard Gold surface finish, an electrolytic process using an electric current or an immersion process is needed, depending on the PCB design. For Complete PCB Assembly projects, where we fabricate and assemble the boards, we will also need to consider the poor solderability of this finish; a very active flux will be required to solder effectively to the hard-gold-plated pad