The electroplating process uses an electric current to dissolve metal and deposit it onto a surface. The process works using four primary components:
Anode: The anode, or positively charged electrode, in the circuit is the metal that will form the plating.
Cathode: The cathode in the electroplating circuit is the part that needs to be plated. It is also called the substrate. This part acts as the negatively charged electrode in the circuit.
Solution: The electrodepositing reaction takes place in an electrolytic solution. This solution contains one or more metal salts, usually including copper sulfate, to facilitate the flow of electricity.
Power source: Current is added to the circuit using a power source. This power source applies a current to the anode, introducing electricity to the system.
Once the anode and cathode are placed in solution and connected, the power supply supplies a direct current (DC) to the anode. This current causes the metal to oxidize, allowing metal atoms to dissolve in the electrolyte solution as positive ions. The current then causes the metal ions to move to the negatively charged substrate and deposit onto the piece in a thin layer of metal.
As an example, consider the process of plating gold onto metal jewelry. The gold plating metal is the anode in the circuit, while the metal jewelry is the cathode. Both are placed in solution and DC power is supplied to the gold, which dissolves in solution. The dissolved gold atoms then adhere to the surface of the base metal jewelry, creating a gold coating.
While this process is constant, three factors can impact the quality of the plating. These factors are the following:
Bath conditions: Both the temperature and the chemical composition of the bath impact how effective the electroplating process is.
Part placement: The distance the dissolved metal needs to travel will affect how effectively the substrate is plated, so the placement of the anode relative to the cathode is important.
Electrical current: Both the voltage level and the application time of the electrical current plays a role in the efficacy of the electroplating process.