The water cleaning process of PCB circuit board uses water as the cleaning medium. A small amount (usually 2% to 10%) of surfactants, corrosion inhibitors and other chemicals can be added to the water. The PCBA cleaning process is completed by washing, washing and drying the source of pure water or deionized water several times.
The advantage of water cleaning is that the cleaning medium is generally non-toxic, does not endanger the health of workers, and is non-flammable and non-explosive.
Good safety, water cleaning has a good decontamination effect on particles, rosin-based flux, water-soluble pollutants and polar pollutants. The rubber parts and coatings are not swelled or cracked, so that the marks and symbols on the component surface can be kept clear and complete, and they will not be washed off. Therefore, water cleaning is one of the main processes of non-ODS cleaning.
The disadvantage of water washing is that the entire equipment investment is large, and it is also necessary to invest in water production equipment of pure water or deionized water. In addition, it is not suitable for non-hermetic devices, such as adjustable potentiometers, inductors, switches and other water vapor entering the device is not easy to discharge, and may even damage the components.
Water washing technology can be divided into two processes: pure water washing and adding surfactant in water. The typical PCBA process is as follows:
Water + surface activity → water → pure water → ultrapure water → hot air → washing → washing → rinsing → rinsing → drying
Generally, an ultrasonic device is added in the washing stage, and an air knife (nozzle) device is added in addition to the supersonic wave in the cleaning stage. The water temperature is controlled at 60-70 ° C, the water quality requirement is very high, and the resistivity is 8-18MQ · cm. This alternative technology is suitable for PCB manufacturers with large batches production and high product reliability requirements. For small batch cleaning, small cleaning equipment can be selected.
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