How to Clean a Printed Circuit Board?

Preparation before Cleaning

Before cleaning, all connectors on the circuit board including jumper, card board, battery and IC must be carefully unplugged one by one. The potentiometer, transformer and solenoid coil (inductance coil) must also be removed from the circuit board. . [Note: Non-electronic professionals should not perform this operation, because if you do not have electronic expertise, it is easy to damage the parts and circuit boards during disassembly. Fortunately, computer-related circuit boards basically do not have these components].

Therefore, once water enters the components, the water droplets in the gaps or between the turns are difficult to be swept out by the compressed air and the moisture is difficult to be dried. The disassembly must be recorded one by one to ensure that there will be no mistakes in the restoration after cleaning. At the same time, check whether the electrolytic capacitor on the circuit board is leaking or bulging on the top. If so, remove it and mark the spot so that it can be replaced with a new product of equivalent value after the circuit board is cleaned.

For the circuit board of the computer power supply, you should also check whether there are cracks or unsoldering between the pads of the printed circuit and the component feet, especially the high-power components. If there are cracks or unsoldering, they should be repaired immediately. Repair the cracks right when you find it, otherwise it is easy to miss these cracks and unsoldering.

Cleaning Method

1. Before cleaning, use a clean soft paint brush (1 inch wide brush is better) and dry compressed air with a pressure of about 0.1Mpa (that is, 1kg/cm2) to remove the dust on the circuit board.

2. For cleaning, a special cleaning fluid (commonly known as board washing water) for washing circuit boards can be used. This fluid can be found at a specialized store. If there is no board washing water, you can do as follows: (now we generally don’t use board washing water) rinse with tap water first, pay attention to the water flow to be soft, not too strong, carefully brush with a soft brush while flushing, do the same for both sides of the circuit board .

3. Then use a soft brush with neutral soap to carefully and gently clean every part of the circuit board, especially the jumper plugs, the inside and bottom of the slots (CPU slot, AGP slot, PCI slot, memory slot). The bottom of the IC socket, the north-south bridge chip, the BIOS chip and the bottom of each other IC chip, the bottom of the large capacitor, etc. should be carefully cleaned, and the small capacitors and other components that are installed upright should not be touched when operating; if the soap foam is very dirty, it must be rinsed with clean water and then scrubbed with soap again until the soap foam is white.

4. Then slowly rinse the circuit board thoroughly with clean water. Note: The soapy water must be rinsed thoroughly.

5. After washing, use dry compressed air with a pressure of about 0.1Mpa [i.e. 1kg/cm2] to blow away the water droplets, especially jumper plugs, slots (CPU slot, AGP slot, PCI slot, memory slot). The inside and bottom, the bottom of the IC socket, the north-south bridge chip, the BIOS chip and the bottom of each other IC chip, the bottom of the large capacitor, etc., should be air dried from different directions, and try to blow any water droplets in the gap away. If you don’t have compressed air, you can use a rubber hand pump that is especially for watch and camera repair professionals, but this stuff can be tiring.

6. Use double distilled water or anhydrous alcohol to wash the circuit board once more time (make the side where the components are soldered face up, place the circuit board diagonally, and use a clean oil paint brush of No. 10 to 12 to dip it in anhydrous alcohol. From top to top and  to the ground for cleaning). Carbon tetrachloride is more effective, but it is toxic, and you must be careful when using it. Don’t use it unless it is necessary. It is generally recommended not to use carbon tetrachloride.

At this point, the cleaning process is completed. This cleaning method does not only clean the boards thoroughly, saves money, and is environmentally friendly and healthy.

As a professional FPC soft board manufacturer, XPCB Limited is so honored to have worked together with many of you. At XPCB Limited we are always more than ready to assist our new customers in any way we can.  Please feel free to contact us at any time if you have any question.