Cause analysis of solder joint with tin
1. The welding temperature is low, so that the viscosity of the molten solder is too large.
2.PCB preheating is low, the component and PCB absorb heat during welding, so that the actual welding temperature is reduced.
3. The activity of the flux is poor or the proportion is too small, resulting in the solder concentrated in a piece can not be spread out.
4. Poor weldability of welding pad, cartridge hole or pin, insufficient infiltration, resulting in bubbles wrapped in the solder joint.
5. The proportion of tin in solder decreases, or the composition of Cu increases, the consistency of solder increases, and the fluidity of tin becomes worse.
6. Too much solder slag causes solder alloy wrapped tin slag to stay on the solder joint, so the solder joint becomes larger.
Solder joint tin improvement measures
1. Adjust the welding peak temperature and welding time.
2. Set the preheating temperature according to PCB size, board layer, number of components, and whether there are attached components.
3. Replace the flux or adjust the appropriate proportion.
4. Improve the processing quality of PCB board, components first in first out, do not store in humid environment.
5. Adjust the solder alloy composition.
6. Clean up tin residue before each shift ends.
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