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Instruction about PCB surface finish


There are several different surface finish in PCB manufacturing, customers can select the one which most suitable their products, we introduced a few types as following:


1.HASL hot air leveling


Tin spraying is a common processing method in the early days of PCB board proofing. Now divided into lead-sprayed tin and lead-free tin-sprayed. The advantages of tin spraying: After the PCB is completed, the copper surface is completely wetted (the tin is completely covered before soldering), suitable for lead-free soldering, the process is mature and the cost is low, suitable for visual inspection and electrical testing, and it is also a high-quality and reliable PCB board One of the proofing processing methods.


2. Chemical Nickel Gold (ENIG)


Nickel gold is a relatively large-scale PCB board sample surface treatment process. Remember: the nickel layer is a nickel-phosphorus alloy layer, which is divided into high-phosphorous nickel and medium-phosphorous nickel according to the phosphorus content. The application is different. the difference. The advantages of nickel nickel: suitable for lead-free soldering; the surface is very smooth, suitable for SMT, suitable for electrical testing, suitable for switch contact design, suitable for aluminum wire bonding, suitable for thick plates, and strong against environmental attacks.


3. Gold plating


Nickel gold electroplating is divided into "hard gold" and "soft gold". Hard gold (such as gold-cobalt alloy) is commonly used on gold fingers (contact connection design). Soft gold is pure gold. Nickel electroplating is widely used on IC carrier boards (such as PBGA). It is mainly used for bonding gold and copper wires. However, it is suitable for electroplating on IC carrier boards. The area where the gold fingers are bound requires additional conductive wires to be plated. The advantages of electroplating nickel gold PCB board proofing: suitable for contact switch design and gold wire binding; suitable for electrical testing




Nickel-palladium gold (ENEPIG) is now gradually starting to be used in the PCB board proofing field, and has been used in semiconductors before. Suitable for gold and aluminum wire binding. The advantages of proofing with nickel-palladium gold pcb board: applied on IC carrier board, suitable for gold wire bonding and aluminum wire bonding. Suitable for lead-free soldering; compared with ENIG, there is no nickel corrosion (black disk) problem; the cost is cheaper than ENIG and electric nickel gold, suitable for a variety of surface treatment processes and exists on the board. 

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