What is electroplating?
Electroplating is the process of depositing metal or alloy on the surface of the substrate using the principle of electrolysis to form a uniform, dense and good binding force metal layer. The function is to prevent metal oxidation (such as rust), improve wear resistance, electrical conductivity, reflective property, corrosion resistance (copper sulfate, etc.) and improve beauty.
In addition to electrical conductors, electroplating can also be used on specially treated plastics. The main uses of electroplating, such as chromium plating, zinc plating, copper plating, nickel plating, etc., include preventing metal oxidation (such as rust) and decoration. The outer layer of coins, for example, is electroplated.
The most common electroplating is chromium plating, which can form a beautiful and bright surface layer on the surface of the component. The surface layer of electroplated chromium is blue-white metallic color, which is not easy to discolor and oxidize in the air.
The surface layer of electroplated nickel is reddish metallic color, which is easier to oxidize after a long exposure time in the air and will become reddish brown metallic color.
The plating process
- Connect the plated metal to the positive electrode, or add the soluble salt to be gold-plated in the tank.
- The object to be plated is connected to the negative electrode.
- The positive and negative electrodes are connected by an electrolyte solution composed of positive ions of the plated metal.
- After the direct current power supply, the positive metal will release electrons, and the positive ions in the solution will be reduced (to obtain electrons) into atoms at the cathode and accumulate in the cathode surface
The use and advantages and disadvantages of common electroplated metals
- Copper
- Uses: Printed circuit board, anti-carburizing, increase electrical conductivity, friction reduction during extrusion, repair parts size, conduction
- Advantages: Good electrical conductivity, low stress, improve the adhesion ability of the coating, and corrosion resistance
- Disadvantages: Copper is easy to oxidize, and post-treatment needs to be done to prevent oxidation
- Nickel
- Uses: electrode material, decorative and protective coating, primer.
- Advantages: good plasticity, easy to press, has good mechanical processing and mechanical properties, good stability, oxidation resistance, corrosion resistance, nickel plating deformation is small, roughness is low, wear resistance.
- Disadvantages: nickel is easy to passivation, it is necessary to complete the plating as far as possible, and the intermediate power failure is easy to layer the coating.
- Gold
- Application: Used in electronics industry, aerospace, aviation, microelectronics technology and decoration technology, conductive, wire.
- Advantages: Excellent chemical stability. Soft gold is soft, very good ductility, strong binding force; Hard gold wear resistance is good, beautiful. Used to improve conductive contact impedance and enhance signal transmission.
- Cons: High cost.
The factors affecting the quality of electroplating
There are many factors affecting the quality of electroplating film, including current density, electric field distribution, line width, plating solution composition, circulation mode and so on.
From the power supply
- The current density affects the crystallization effect of the coating
- The current waveform has an effect on the crystalline structure, brightness, dispersion and covering ability of the plating solution. Now use more pulse current
- The shape, size and position of the electrode affect the distribution effect of the coating
Base parts
- The better the clean and smooth substrate surface coating effect
- Shape affects current distribution and position positioning
