There are up to 20 processes involved in PCB design and production. Poor soldering can be a significant challenge. Insufficient tinning on the circuit board can lead to issues such as circuit voids, broken traces, “dog-bone” defects, open circuits, and more. If the hole plating is too thin, the hole may not be properly plated; similarly, if the hole copper is too thick, it can also result in plating problems. As a result, poor soldering often necessitates rework or, in the worst cases, discarding previous efforts and starting over. Understanding the causes of poor soldering is therefore crucial in the PCB industry.
The appearance of poor soldering is typically linked to the cleanliness of the PCB surface. If the surface is clean and free of contamination, poor soldering issues are less likely to occur. Another common cause is inadequate flux or improper temperature during the soldering process. The most common soldering defects in printed circuit boards are generally related to the following issues:
1. Particulate impurities in the plating layer or grinding debris remaining on the surface of the circuit during the substrate manufacturing process.
2. The board surface is contaminated with grease, impurities, and other debris, or there may be residual silicone oil.
3. There are areas on the board surface lacking tin, and particulate impurities are present within the plating layer.
4. The high-potential coating is rough, exhibiting signs of burning, and there are areas on the surface without tin.
5. The tin surface of the substrate, or certain areas, has severely oxidized, and the copper surface appears dull.
6. The plating on one side of the board is intact, while the other side shows poor plating, with distinct bright edges around the low-potential holes.
7. The low-potential holes have clear bright edges, and the high-potential coating is rough with signs of burning.
8. Insufficient temperature or time during the soldering process, or improper flux usage, may be contributing factors.
9. Tin plating fails to cover large areas at low potential, the board surface appears slightly dark red or red, with a complete coating on one side and a poor coating on the other.
The causes of poor tinning on circuit boards are generally attributed to the following:
1. The bath composition is unbalanced, the current density is too low, and the plating time is insufficient.
2. The anodes are too few in number and unevenly distributed.
3. The concentration of the tinting agent is either too low or excessively high.
4. The anode is too large, the current density is too high, the pattern’s wire density is too thin in certain areas, and the light agent is not properly adjusted.
5. There is residual film or organic matter remaining on the board before plating.
6. The current density is too high, and the plating solution is not adequately filtered.
The following outlines the improvement and prevention strategies for PCB electro-tinning defects:
1. Regularly conduct chemical analyses and adjust the syrup composition in a timely manner to increase current density and extend plating time.
2. Monitor anode consumption periodically and add anodes as necessary.
3. Perform Hearst cell analysis and adjust the content of the light agent accordingly.
4. Adjust the anode distribution rationally, reduce the current density appropriately, design the wiring or board connections properly, and fine-tune the light agent.
5. Strengthen pre-plating treatments.
6. Reduce the current density and maintain the filter system regularly or carry out weak electrolysis treatment.
7. Strictly control the storage time and environmental conditions during the storage process, ensuring adherence to production process standards.
8. Use solvents to clean debris; for silicone oil, use a specialized cleaning solvent.
9. Control the temperature during the PCB soldering process to be between 55-80°C, ensuring sufficient preheating time.
10. Use soldering flux properly.
The above summarizes the key points related to poor tinning in PCB design.
The appearance of poor soldering is typically linked to the cleanliness of the PCB surface. If the surface is clean and free of contamination, poor soldering issues are less likely to occur. Another common cause is inadequate flux or improper temperature during the soldering process. The most common soldering defects in printed circuit boards are generally related to the following issues:
1. Particulate impurities in the plating layer or grinding debris remaining on the surface of the circuit during the substrate manufacturing process.
2. The board surface is contaminated with grease, impurities, and other debris, or there may be residual silicone oil.
3. There are areas on the board surface lacking tin, and particulate impurities are present within the plating layer.
4. The high-potential coating is rough, exhibiting signs of burning, and there are areas on the surface without tin.
5. The tin surface of the substrate, or certain areas, has severely oxidized, and the copper surface appears dull.
6. The plating on one side of the board is intact, while the other side shows poor plating, with distinct bright edges around the low-potential holes.
7. The low-potential holes have clear bright edges, and the high-potential coating is rough with signs of burning.
8. Insufficient temperature or time during the soldering process, or improper flux usage, may be contributing factors.
9. Tin plating fails to cover large areas at low potential, the board surface appears slightly dark red or red, with a complete coating on one side and a poor coating on the other.
The causes of poor tinning on circuit boards are generally attributed to the following:
1. The bath composition is unbalanced, the current density is too low, and the plating time is insufficient.
2. The anodes are too few in number and unevenly distributed.
3. The concentration of the tinting agent is either too low or excessively high.
4. The anode is too large, the current density is too high, the pattern’s wire density is too thin in certain areas, and the light agent is not properly adjusted.
5. There is residual film or organic matter remaining on the board before plating.
6. The current density is too high, and the plating solution is not adequately filtered.
The following outlines the improvement and prevention strategies for PCB electro-tinning defects:
1. Regularly conduct chemical analyses and adjust the syrup composition in a timely manner to increase current density and extend plating time.
2. Monitor anode consumption periodically and add anodes as necessary.
3. Perform Hearst cell analysis and adjust the content of the light agent accordingly.
4. Adjust the anode distribution rationally, reduce the current density appropriately, design the wiring or board connections properly, and fine-tune the light agent.
5. Strengthen pre-plating treatments.
6. Reduce the current density and maintain the filter system regularly or carry out weak electrolysis treatment.
7. Strictly control the storage time and environmental conditions during the storage process, ensuring adherence to production process standards.
8. Use solvents to clean debris; for silicone oil, use a specialized cleaning solvent.
9. Control the temperature during the PCB soldering process to be between 55-80°C, ensuring sufficient preheating time.
10. Use soldering flux properly.
The above summarizes the key points related to poor tinning in PCB design.
