Pollutants are defined as any surface sediments, impurities, residues and adsorbents that reduce the chemical, physical or electrical properties of PCBA to an unqualified level. The main points are as follows:
1. components of PCBA, pollution or oxidation of PCB will bring pollution to PCBA panel.
2. In the production and manufacture of PCBA, solder paste, solder and solder wire are needed to be used for welding. In the process of welding, solder flux will produce residues on the PCBA plate surface, which is the main pollutant.
3. Handmarks will be produced during manual welding. There will be some footprints of wave soldering claws and welding pallets (fixtures) during wave soldering. There may also be other types of contaminants on the PCBA surface, such as blocking glue, residual glue of high temperature tape, hand marks and flying dust.
4. Dust, vapor, smoke, micro-particulate organic matter of water and solvent, and the pollution of charged particles adhering to PCBA caused by static electricity.