Moisture, dust and salt spray are the important factors that cause PCBA failure. The electronic circuit board components can be coated with three anti - salt spray, anti - humidity and anti - mold paint to resist the impact of harsh environment on the circuit and components, and increase the mechanical strength and reliability, to prevent any condensation temperature changes abruptly when the leakage between the printed wiring short circuit breakdown, even for work under the condition of high voltage and low pressure of PCB can improve creepage between wires, breakdown phenomenon, So as to improve the reliability of products.
The PCB needs to be cleaned before PCBA triple spray. To reach the cleanliness index, the commonly used cleaning methods are alcohol, gasoline, trichloroethylene or water cleaning process, recommended to use water cleaning technology, the cleaning process is green and environmental protection, the use of this process can completely and effectively remove the flux residue. The power module in the PCB module containing the power module is usually pouted with silicone oil substances. The biochemical reaction is likely to occur when the power module is soaked and cleaned in solvents such as alcohol and gasoline, and the surface of the PCB is contaminated by silicone oil substances. When PCBA is polluted by organosilicon, the coating will produce discontinuous area, resulting in the coating can not be uniformly attached to the surface of the board and affect the protection performance. For the printed board with power module devices, the practical work is usually carried out by dipping in the solvent for local scrubbing, to avoid the silicone oil in the power module seepage pollution of the board surface, resulting in non-stick paint affect the protection performance.
To investigate the protective effect of the coating is actually to investigate the bonding degree of the coating and the solder resistance film. Different solder resistance films are not consistent with the bonding force of the coating due to the difference in composition and content. The adhesion degree of the coating is closely related to the molecular polarity of the PCB solder film and the coating.
