When the residue remains on the PCBA, it is easy to cause the adsorption and condensation of moisture and dust, and may also cause poor contact in the ICT test, which affects the accuracy of the test result. Under high temperature conditions, the flux residue may be rearranged directly. Cause a short circuit or leakage. For high-frequency and high-speed circuits, even if the circuit is normal, the decomposition of solid polymer will lead to changes in leakage current, dielectric constant and loss coefficient. This will result in weakened signal integrity and power loss, which will eventually lead to product failure. In order to ensure product quality, we need to use flux to clean PCBA to avoid affecting product testing and life cycle. Therefore, alcohol must be used to clean the PCBA board. The cleaning method can immerse the cleaning brush in alcohol and brush the area containing the flux. Do not use too much pressure, as this may trigger damage to the solder display. If necessary, repeat the above steps to eliminate residual flux deposits. The control and cleaning of flux residues have become a research hotspot in the electronics assembly industry. Whether it is OEM equipment manufacturers or CEM, whether flux manufacturers or end users, they are improving flux performance, expanding flux process parameters and controlling the impact of residues on products.