Particle Ejection
Rapid ejection of molten droplets occurs when gas pressure builds up inside a solder joint. The phenomenon of solder spattering is often caused by the moisture or volatiles in the flux escaping too violently. These tiny beads of metal land on the board surface and can create unexpected electrical paths.
This defect is a sign of an incorrect thermal profile or poor material storage.
Contamination Risk
Metallic debris on the circuit board poses a threat to the long-term reliability of the device. Solder spattering creates loose particles that might move during the life of the product and cause a short circuit. These beads are often so small that they are difficult to see with the naked eye.
Such contamination requires a thorough cleaning process to remove the hazardous debris.
Defect Mechanism
High heating rates in the preheat zone are the primary cause of this explosive vapor release. To minimize solder spattering, the ramp rate must be controlled to allow gases to escape gradually. This prevents the pressure from reaching the point where it forcibly ejects the molten metal.
Proper handling of the solder paste also ensures that it does not absorb excess moisture from the air. The presence of these spatters is a clear indicator of a process that is out of control.
