Several PCB Surface Finish Methods

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The current surface finish methods are the following:

1. Hot air solderleveling (HASL)

During the process of applying molten tin-lead solder to the surface of the Printed Circuit Board (PCB) and leveling it with heated compressed air, a coating is formed that is resistant to copper oxidation and provides good solderability. This process is known as hot air leveling flat soldering. The coating is about 1 to 2 mil thick and is formed at the junction of copper and tin metal compounds.

2. Organic antioxidant(OSP)

On a clean bare copper surface, a layer of organic film grows chemically, which has anti-oxidation, thermal shock resistance, and moisture resistance properties. This film protects the copper surface from rusting (oxidation or sulfide, etc.) in normal environments. Moreover, during subsequent high-temperature welding, the film assists in quickly removing the flux for welding.

3. Chemical nickelplating gold

Wrapping a thick layer of copper on the surface using a nickel-gold alloy provides good electrical properties and long-term protection of the PCB. Unlike OSP (organic solderability preservatives), which is only used as a rust barrier, the nickel-gold alloy can be useful during long-term PCB use and achieve good electrical performance. Additionally, it has other surface treatment processes that are not patient in the environment.

4. Chemical silver

The process of OSP and electroless nickel/gold immersion is relatively simple and fast. The OSP and electroless nickel/gold immersion processes provide good electrical properties and solderability even in heat, humidity, and contaminated environments but are tarnished. However, because there is no nickel below the silver layer, silver does not have the same physical strength as electroless nickel/gold immersion.

Several PCB Surface Finish Methods

5. Nickel plating

Conductors on a PCB's surface require a nickel plating layer over a layer of gold plating. This is done to prevent diffusion between the copper and gold. There are two types of nickel plating available - soft and hard gold. Soft gold, which is not very shiny, is used for gold lines on chip packages. Hard gold,which has a smooth and hard surface, contains cobalt and other elements and looks shinier. This type is mainly used for non-welding electrical interconnections (such as gold fingers).

6. PCB mixed surface finish technology

For achieving a better surface finish, there are various surface treatment methods available, such as nickel gold with anti-oxidation, nickel-plated gold, nickel-plated hot air leveling, and nickel-plated gold with hot air leveling.

RoHS is a mandatory standard set by the EU legislation with the full name "Restriction of Hazardous Substances in the Use of Electrical and Electronic Equipment Directive" (Restriction of Hazardous Substances). The standard was implemented on July 1, 2006, to standardize electrical and electronic products, materials, and process standards, making them more conducive to human health and environmental protection. The purpose of this standard is to eliminate six substances, namely lead, mercury, cadmium, hexavalent chromium, polybrominated biphenyls, and polybrominated diphenyl ethers in motor and electronic products. The standard also stipulates that the content of lead should not exceed 0.1%.

Why Choose China PCBA Supplier KSPCBA as Your PCB Surface Finish Manufacturer?

– Experienced and skilled team

– State-of-the-art equipment

– Strict quality control

– Excellent customer service

– Competitive price