PCB factories use different surface treatment methods for circuit board proofing. Each surface treatment method has its own unique characteristics. Taking chemical silver as an example, its process is extremely simple. It is recommended for lead-free soldering and smt, especially for The effect of fine lines is better. The most important thing is to use chemical silver for surface treatment, which will greatly reduce the overall cost and lower the cost. Today we will introduce several common surface treatment methods for PCB board proofing.
1. HASL hot air leveling (that is, often said tin spray)
Tin spraying is a commonly used processing method in the early days of PCB board proofing, and it is now divided into lead spraying tin and lead-free spraying tin. 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
Nickel gold is a relatively large-scale PCB board sample surface treatment process. Remember: the nickel layer is a nickel-phosphorus alloy layer. It 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. Nickel plating
Electroplated nickel gold 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 suitable for bonding gold and copper wires. However, it is suitable for electroplating on IC carrier boards. The area where the gold fingers are bound needs additional conductive wires to be electroplated. The advantages of electroplated nickel-gold PCB board proofing is that it is suitable for contact switch design and gold wire bonding, suitable for electrical testing.
4. Nickel palladium
Nickel palladium is now gradually beginning to be applied in the PCB board proofing field, and has been used in semiconductors before. Suitable for gold and aluminum wire binding. The advantage of using nickel-palladium-gold PCB board proofing is that it is applied on IC carrier board, suitable for gold wire bonding, aluminum wire bonding, and 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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