Causes and Measures for Poor Tinning in PCB Design

There are 20 processes in the PCB design and manufacturing process. The bad tinning is really a headache. The poor tin on the circuit board may lead to sand holes, line collapse, line dog teeth, open circuit, and line sand hole lines. If the copper is thin, the hole is copper-free; if the copper is thin, the hole is copper-free. If the copper is thin, the hole is copper-free. If the tin is not clean, the number of times of returning tin will affect the quality of the coating. The problem, therefore, the failure to meet the tin often means that it needs to be re-welded or even abandoned, and needs to be re-made. Therefore, in the PCB industry, it is important to understand the reasons for the bad tin.

The occurrence of poor tinning is generally related to the cleanliness of the surface of the PCB. If there is no pollution, there will be no defects in the tin. Secondly, the flux itself is poor, and the temperature is high. Then the common electrical tin defects in printed circuit boards are mainly reflected in the following points:

1. The plate coating has particulate impurities, or the substrate has polished particles left on the surface of the line during the manufacturing process.
2. The board is covered with grease, impurities, etc., or there is silicone oil residue.
3. There is a sheet of electricity on the surface of the board, and there is grain impurities on the surface of the board.
4. The high-potential coating is rough, and there is a phenomenon of burning the plate.
5. The tin surface oxidation of the substrate or part and the darkening of the copper surface are serious.
6. One side of the coating is complete, one side is poorly plated, and the low potential hole has obvious bright edges.
7. The low potential hole has a bright edge phenomenon, the high potential plating is rough, and there is a burning phenomenon.
8. There is no guarantee of sufficient temperature or time during the soldering process, or the flux is not being used properly.
9. Low-potential large-area plating is not tinned, the surface of the board is slightly dark red or red, one side is completely plated, and one side is poorly plated.

The reasons for the poor soldering of the circuit board are mainly reflected in the following points:

1. The bath solution is out of tune, the current density is too small, and the plating time is too short.
2. The anode is too small and unevenly distributed.
3. A small amount or excess of tin light agent.
4. The anode is too long, the current density is too large, the local wire density of the pattern is too thin, and the light agent is out of adjustment.
5. There is a residual film or organic matter locally before plating.
6. The current density is too large and the plating solution is insufficiently filtered.

We have summarized the improvement and prevention of the poor electrical condition of PCB board:

1. Periodic analysis of the composition of the syrup should be added in time to increase the current density and extend the plating time.
2. Check the anode for a reasonable amount of supplemental anode.
3. Hach's groove analysis adjusts the light agent content.
4. Reasonably adjust the distribution of the anode, reduce the current density in an appropriate amount, reasonably design the wiring or panel of the board, and adjust the light agent.
5. Strengthen the pre-plating treatment.
6. Reduce current density, regular maintenance of the filtration system or weak electrolytic treatment.
7. Strictly control the storage time and environmental conditions of the storage process, and the production process is strictly operated.
8. Use solvent to wash debris. If it is silicone oil, then it needs to be cleaned with special cleaning solvent.
9. Control the temperature during the PCB soldering process at 55-80°C and ensure sufficient warm-up time
10. Proper use of flux.