Just pure gold (100 percent) or 24 karat gold is way too soft for a metal. This softness allows gold’s ductility (ability to be drawn into wires) and malleability (ability to be hammered into sheets).

Yes, you can use any of the final finishes available for rigid PCBs, but whether you should use them depends on the application. Some standard finishes used on rigid PCBs are not suitable for flex ...