In the process of PCBA processing, solder paste and flux will produce residues, which contain organic acids and decomposable ions. Among them, organic acids have corrosive effect, and the residual ions in the pad will cause short circuit. Moreover, these residues on the PCBA board are dirty and do not meet the customer's requirements for product cleanliness. At the same time, it will also affect the stability of the PCBA board. Therefore, it is necessary to clean the PCBA board.