Knowledge of electroplating baths that affect electroplating quality
The main salt is a salt in the plating solution that can deposit the desired metal on the cathode for the purpose of providing metal ions. The concentration of the main salt in the bath must be in an appropriate range, and the concentration of the main salt increases or decreases, and will affect the electrodeposition process and the final coating structure when the other conditions are constant. For example, the main salt concentration increases, the current efficiency increases, the metal deposition rate is accelerated, the coating grain is coarse, the solution dispersion ability decreases.
In some cases, if the metal salt of the main salt in the plating solution is a simple ion, the coating grain is coarse, and therefore, a complex ion plating solution is used. The method of obtaining complex ions is by adding a complexing agent, i.e., a substance capable of complexing the metal ions of the main salt to form a complex. A complex is a "molecular compound" formed by the interaction of simple compounds. In the solution containing the complex, the effect of the plating effect is mainly the relative content of the main salt and the complexing agent, that is, the free amount of the complexing agent, not the absolute content.
Additives are substances that do not significantly alter the conductivity of the coating and can significantly improve the coating properties. According to the role played in the bath, the additives can be divided into: brightener, leveling agent, and anti-fog agent.
Buffer refers to the substance used to stabilize the pH of the solution. These substances are generally composed of weak acid and weak acid salt or weak base and weak base salt, can make the solution encountered alkali or acid, the solution of the pH value of the reduction of the range.
The anode activator is the substance that promotes the activation of the anode. The role of the anodic activator is to increase the current density at which the anode begins to passivate, thereby ensuring that the anode is in an activated state and can be dissolved normally. When the amount of anode activator is insufficient, the anodic dissolution is abnormal and the content of main salt decreases rapidly, which affects the stability of the bath. Serious, the plating can not be normal.
Factors that affect the quality of plating
PH value, additives, current density, current waveform, temperature, stirring speed and so on.
Electroplating can be used with different metal plating, galvanized, nickel, chrome and so on.