Reasons and prevention solutions for poor tin on PCB
Today we will talk about the reasons for bad tin on PCB and the prevention plan.
First of all, if the PCB is not tinned well during the SMT production process, generally speaking, the reason is related to the cleanliness of the bare PCB surface. If there is no dirt, there will be basically no poor tinning. Secondly, poor soldering flux itself is also a reason. In addition, improper temperature setting will also lead to poor tinning. So what are the common tin defects in PCB production and processing? How to solve this problem?
1. The PCB coating has granular impurities, or there are abrasive particles on the circuit surface during the substrate manufacturing process.
2. There are grease, impurities and other sundries on the surface of the board, or there is residual silicone oil
3. There are flakes of tin-free on the surface of the board, and there are granular impurities in the coating of the board.
4. The high-potential coating is rough and scorched, and the surface of the tin-free board is peeled off.
5. The tin surface of the substrate or parts is severely oxidized, and the copper surface is dull.
6. The coating on one side is intact, and the coating on the other side is poor. There are obvious bright edges on the edge of the low potential hole.
7. There are obvious bright edges on the edge of the low potential hole, and the high potential coating is rough and burnt.
8. Insufficient temperature or time is not guaranteed during the soldering process, or the flux is not used correctly
9. Low potential cannot be tinned in a large area, the surface of the board is slightly dark red or red, the coating on one side is complete, and the coating on the other side is poor.
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PCB electrical tin defect improvement and prevention solutions:
1. Regularly carry out chemical analysis and syrup composition analysis, add it in time, increase the current density, and prolong the plating time.
2. Check the anode consumption from time to time, and add anodes reasonably.
3. Hexceles analysis to adjust light agent content
4. Reasonably adjust the distribution of the anode, properly reduce the current density, rationally design the wiring or joints of the circuit board, and adjust the light agent.
5. Strengthen the pre-plating treatment.
6. Reduce the current density, regularly maintain the filter system or carry out weak electrolysis treatment.
7. Strictly control the storage time and environmental conditions of the storage process, and strictly operate the production process.
8. Use a solvent to clean the debris. If it is silicone oil, you need to use a special cleaning solvent to clean it
9. The temperature of the PCB welding process is controlled at 55-80°C to ensure sufficient preheating time
10. Use flux correctly.