How to reduce the generation of reflow solder beads on circuit boards

To reduce the generation of reflow solder beads, the following measures can be taken:

1. Control the preheating temperature. The temperature during the preheating stage should be between 120 and 150 degrees Celsius, which can remove volatile solvents in the solder paste, reduce vibration on the components, and then reduce the force generated by internal gasification of the solder paste. This will reduce the amount of solder beads produced by a small amount of solder paste flowing off the solder pad. At the same time, the preheating temperature should not be too high, otherwise the preheating speed will be faster, increasing the internal gasification of the solder paste and forming solder beads. So temperature control is very important.

2. Check the quality of the solder paste. The quality of solder paste should be qualified, such as metal content, metal oxidation degree, etc., which should be within the standard range. The metal powder and flux should not be layered.

3. Control the thickness of the solder paste on the PCB board to be moderate, and ensure that the proportion of solder flux in the solder paste is properly mixed and the activity of the solder flux is moderate.

4. Ensure that the PCB board is dried to avoid incomplete evaporation of moisture and solvents, which may cause boiling and splashing of solder beads when reaching the reflow soldering temperature zone.

5. Ensure that the solder paste does not enter too much water vapor during use or place it in a dry environment to prevent water vapor from entering.