-How to clean PCB with alcohol

The spray paint of circuit board does not dissolve in alcohol and will not melt and fall off due to alcohol cleaning. Alcohol does not contain electrolyte, so it will not produce conductive short circuit. Alcohol can wipe off greasy and deposited dust to make the circuit board bright and clean as before. Alcohol is easy to volatilize. It will dry out in a few minutes in a ventilated place without residue.

Cleaning method: after the circuit board is removed, it is better to blow away the floating dust with a blower first, and then use a soft hair brush to remove the adhered dust and the dust in the corner, and then use alcohol cotton yarn to gently wipe and dry in the ventilation place. By the way, do not use water or other solvents to clean and do not soak, so as not to damage the components on the circuit board.

-How to clean the wet PCB

Generally, some of the drags and reels removed from the mounter are stored in a dry environment until they are used again. This storage must consist of a drying chamber or a resealed drying bag with desiccant. Many assembly manufacturers believe that the time that parts are exposed in dry storage is terminated. In fact, once the parts have been exposed for a certain time (more than one hour), the absorbed moisture will remain in the package and spread to the central interface, which may cause harm. For this reason, the standard does not say to stop the timing of exposure time.

Recent findings clearly show that for components sensitive to high humidity (levels 4-5a), the time for dry storage is as important as before production exposure. From an example cited in paper 1 on the subject, it is shown that PLCC classified as level 5 (usually 48 hours of production life) after only 16 hours of exposure and then dry storage for 70 hours still exceeds the critical moisture level. Anyway, it is a good way to put the components into dry storage. The drier the environment, the slower the moisture absorption process. If the parts stay in the dry environment for enough time, the process will reverse and the parts will start to dry again. Also, if the exposure time is limited, the entrained moisture will be removed in a relatively short time. IPC / JEDEC standard stipulates that the exposure time can be reset to zero for parts exposed for less than 8 hours in dry environment for 5 times. Once again, the real problem is to provide a workable working procedure for the production operator.

Part of the measurement of drying control can be achieved by regular inspection. The frequency of inspection largely depends on the sensitivity level and the number of product transitions and related feeder settings. In fact, it means that the production operator has to perform additional date and time calculations based on the previous records and eventually remove the component from the mounter before it expires.

-How to clean the corroded PCB

1) Clean the corroded PCB with water repeatedly. Wipe off the paint with banana water and wash it several times to make the PCB clean without any corrosive liquid. Apply a layer of rosin solution and drill after drying.

2) Clean the corroded circuit board with anhydrous alcohol first, and clean the back of the same location. Then remove the leaking battery. Remove the battery and clean the circuit board again. Then solder the corroded IC pin again. Check whether any circuit is corroded after soldering. If it is broken, connect the flying wire. After confirming that the circuit is correct, the battery can be welded. You can test it there is no problem.

3) After corrosion, it shall be taken out in time and washed with water. Drill holes in the pad, polish the copper foil with fine sandpaper, and then coat it with rosin alcohol solution. When it's cool and dry, it's finished.