Eight surface treatments for circuit boards

Eight surface treatments for circuit boards

In addition to the light plate, the circuit board will do surface treatment, the root cause is to better preservation, to prevent the oxidation of the circuit board surface, to lay the foundation for the customer behind the patch. Today by the hour to introduce some of our tongchuangxin precision circuit co., LTD often do some surface treatment methods.

1. Hot air leveling (tin spraying)

Hot air leveling, also known as hot air solder leveling (commonly known as tin spraying, at the same time there is no lead tin spraying process, it is in the PCB surface coated with molten tin solder and heated compressed air blowing process, so that it forms a layer not only resistant to copper oxidation, but also can provide good solderability coating. Tin - sprayed solder and copper form copper - Sikkim intergeneric compounds at the junction.

2. Organic solderability protective agent (OSP)

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OSP is a process for surface treatment of copper foil on printed circuit board (PCB) in accordance with the RoHS  directive. OSP is short for Organic Solderability Preservatives. Simply put, OSP is the chemical process of growing an Organic membrane on a clean, bare copper surface. This film has oxidation resistance, heat shock resistance, moisture resistance, to protect the copper surface in the normal environment will not continue to rust (oxidation or sulfurization, etc.);However, in the subsequent welding high temperature, the protective film must be easily removed by the flux quickly, so that the exposed clean copper surface can be immediately combined with the molten tin to form a solid solder joint in a very short time.

3. The whole plate is plated with nickel gold

Nickel-gold plating on the surface of the PCB conductor is first plated with a layer of nickel and then a layer of gold, nickel plating is mainly to prevent the diffusion of gold and copper. There are now two types of electroplated nickel-gold: soft gold (pure gold, with a dull surface) and hard gold (smooth and hard, wear-resistant, containing other elements such as cobalt, with a bright surface).Soft gold is mainly used for making gold wire in chip packaging. Hard gold is mainly used for electrical interconnections in non-welded areas. The price of full gold plating is very expensive, it is generally not recommended to use this treatment without special needs.

4, immersion gold

Gold is a layer of copper surface wrapped in a thick, electrical good nickel gold alloy, which can protect the circuit board for a long time; In addition, it also has environmental tolerance that other surface treatment processes do not have. In addition, immersion gold can also prevent the dissolution of copper, which will be beneficial for lead-free assembly. It generally lasts for three months, longer than OSPS and tin sprays, is more durable and resistant to oxidation, but is also more expensive than other surface treatments.

5, immersion tin

Since all current solder is based on tin, the tin layer can match any type of solder. immersion Tin sinking process can form flat copper-sik kim inter compound, this property makes the tin with hot air leveling as good solde raility, but not hot air leveling headache flat; immersion Tin plate can not be stored for too long (generally about 1 month), assembly must be carried out according to the order of the tin.

6．immersion silver

The silver technology is between organic coating and electroless nickel plating/ immersion tin. Silver retains good solderability even when exposed to heat, humidity, and pollution, but loses its luster. immersion silver does not have the good physical strength of electroless nickel plating/gold deposition because there is no nickel underneath the silver layer.

7. Chemical nickel palladium gold

The chemical nickel palladium has an extra layer of palladium between nickel and gold compared with the submerged gold, which can prevent the corrosion caused by displacement reaction and make sufficient preparation for the submerged gold. Gold is tightly coated with palladium, providing good contact.

8. Electroplating hard gold

In order to improve the wear resistance of products, increase the number of inserts and electroplating hard gold.

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