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The purpose of circuit board Nickel Plated

Nickel, the chemical element symbol is Ni. Nickel has excellent physical, mechanical and chemical properties, so it has many applications in engineering and industry, such as anti-corrosion, increased hardness, wear resistance and other applications. It is mainly used in alloy formulations such as nickel steel, nickel-chromium steel, nickel-copper, etc. to increase its ability to resist corrosion and oxidation.

In fact, the activity of nickel itself is also very high for oxygen, which means that nickel itself is also very easy to oxidize, but because the oxides (NiO, Ni(OH)2) generated by itself have excellent fineness, they can form a layer of film to cover itself to isolate it from continuing contact with air, so it can resist oxidation, that is to say, nickel will first oxidize itself to form a protective film to protect itself and the bottom metal from continued oxidation.

Therefore, nickel is often used to electroplate other metal surfaces to protect the underlying metal from contact with air and cause oxidation problems. However, its plating layer must achieve defect-free to achieve certain protection. In the early nickel plating process, because the process is not very mature, small holes often occur, so that the bottom metal material under the plating layer cannot be completely sealed, resulting in the problem of bottom metal oxidation after nickel plating. The nickel plating process has gradually matured, and a sealing agent is usually added to the plating bath to solve the problem of porosity.

In addition to the effect of preventing oxidation on the metal surface, nickel plating can also enhance the following mechanical properties:
1、Tensile strength
2、Elongation
3、Hardness
4、Internal
5、Fatigue life
6、Hydrogen embrittlement

In addition, nickel plating also has good resistance to chemical corrosion, and is often used in the chemical, petroleum, food and beverage industries to prevent corrosion, prevent product pollution, and maintain product purity. However, it should be noted that when the oxide protective film of nickel is invaded by the chloride solution, it will form pinhole-shaped corrosion. Generally, the nickel plating layer will not have much problems in neutral or alkaline solutions, but it will be corroded when encountering most of minerals.

What is the purpose of nickel plating on circuit boards?

Nickel plating on the circuit board, its main purpose is to prevent the migration and diffusion between copper and gold, as a barrier layer and anti-corrosion protective layer to protect the copper layer from oxidation, and also prevents the electrical conductivity and solderability cracking. According to IPC-4552's recommendation for ENIG (Electroless Nickel Immersion Gold), its thickness must be at least 3µm/118µ", then can play a protective role. In the process of solder or SMT reflow, the nickel layer will combine with the tin in the solder paste to form a Ni3Sn4 Inter Metallic Compound(IMC), although the strength of this IMC is not as good as Cu6Sn5 that generated by OSP surface treatment, but it is enough to meet the needs of most of today's products.