There are two types of circuit board assembly and welding processes, namely "washing process" and "no-cleaning process". The initial process needs to be washed with water, that is, after the circuit board goes through "Surface Mount or "Wave soldering", pure water or detergent is used to wash off the no-clean pb-free solder paste and solder on the circuit board. With the continuous development of technology, the design of electronic parts on the circuit board is becoming more and more diverse, and the volume is getting smaller and smaller, and some problems have gradually appeared in the washing process. In addition, the cleaning process of the PCB board is really too much. Trouble, in most cases of choosing no-clean solder paste, there is no need to carry out the cleaning process. One less process can not only improve production efficiency, but also save costs.