Electroplating theory analysis

Plating principle contains four areas: plating solution, plating reaction electrode and reaction principle, the metal electrodeposition process.
First, the molybdenum plating solution has six elements: main salt, complexing agent, the salt, buffering agents, anode activator and additives.
The electrochemical reaction in the plating reaction: The figure is a schematic view of a plating apparatus, the parts to be plated as the cathode, the cathode is connected to the DC power supply, the metal anode coupling the positive DC power supply, an anode are immersed in the bath with the female. When an electric potential is applied between the anode and cathode, then the following reaction occurs at the cathode: electrode from the bath and the bath diffuses into the interface of metal ions from the cathode to obtain Mn + n electron, reduction to the metal M. On the other hand, occurs at the anode and the cathode opposite reaction that occurs on the interface anode dissolution of the metal M, the release of metal ions n electron generating M n +.
Electrode and the reaction mechanism
A, electrode potential
When the metal electrode is immersed in a solution containing the metal ions when, there is a balance of the metal loses electrons and the reaction mixture dissolved in the solution of metal ions and precipitation of the metal in the electronic reverse reaction should exist: Mn + + ne = M
Equilibrium potential of the nature and the metal temperature of the solution concentration. For accurate comparison substance to balance the potential of nature, it is required when the solution temperature is 250C, the metal ion concentration was 1mol / L, the measured potential is called the standard electrode potential. A more negative standard electrode potential of the metal are easy to lose electrons are oxidized, and the standard electrode potential value larger metal are easy to obtain electrons is reduced.
B, polarization
The so-called polarization refers to a current through the Tungsten eletrode, the potential deviation from the equilibrium electrode potential of the phenomenon. So, again the current - potential curve is called polarization curves. The polarization effect was mainly due to electrochemical polarization and concentration polarization.
(1) electrochemical polarization
Since the electrochemical reaction rate is less than the cathode external power supply to the speed of electrons, so that the electrode potential in the negative direction of the movement caused by the polarization.
(2) the concentration polarization
As liquid layer adjacent to the electrode sheet bulk of the solution concentration and the concentration polarization arising differences occur, said concentration polarization, which is due to diffusion of ions in the solution caused by the movement speed is less than e.
Plating metal ions in the bath under the action of an external electric field, the electrode reaction and the reduction of the metal atoms on the cathode metal deposition process.
Electroplating is simple terms, that is plated in the presence of salts want a solution to the matrix metal to be plated as the cathode, through the electrolysis, the bath in the plating metal cation want metal deposited on the surface of the base, the formation of deposits.