Why need to clean PCB – how to clean？

In the PCBA production process, solder paste and flux will also produce residual substances, residues that contain organic acids and decomposable ions, among which organic acids have corrosive properties, ionic adhesion in the pad will also cause short-circuit failures, and these residues in the PCBA board is still relatively dirty, and do not meet the user’s standards for product cleanliness. Therefore, PCBA board cleaning is very necessary.

Why Clean a Circuit Board?

Since cleaning a circuit board is not always in most companies’ maintenance routine and adds time and expenses to the manufacturing and repair processes, it is essential to understand why you should regularly clean these devices.

1 .Enhance Aesthetic Appearance of PCB

If you are a PCB engineer, designer, or manufacturer, your products’ visual presentation tells the world much about your work. A greasy-appearance residue on solder joints may spark questions from the quality assurance officers.

2. Improve the Reliability of Circuit Boards
The nature of the end products mostly influences reliability demands. For example, pacesetter devices’ requirements- where PCB malfunctioning can directly cause loss of life- are more strict. Cleaning is needed post assembly, and you should exhaustively test the process for efficiency.

3 .Prevent PCB Component Corrosion
Flux remains on PCBs are acidic. If you fail to remove them, they can absorb moisture from the air and cause corrosion.

4 .Prevent Adhesion Issues with Conformal Coating
When you leave flux on a board before coating, the coating will lift from your PCB’s surface. Adhesion is more common in well-spaced pockets within the solder joints. Furthermore, layers are semi-permeable and can easily let moisture clog the flux deposits, and eventually cause corrosion.

5. Avoid Dendritic Growth from Ionic Residues
Ionic particles resulting from flux deposits, when they come in contact with moisture and when current is flowing, can form a dendritic chain. Since these chains are conductive, they can cause accidental traces that leak current.

What are the contaminants in PCBA production and processing?

Pollutants are defined as all the chemical, physical or electrical properties of PCBA reduced to substandard levels of surface build-up, debris, slag, and adsorption. There are mainly the following aspects:

1.Comprised of PCBA electronic components, PCB’s own pollution or oxidation, etc. will produce PCBA surface pollution;.

2.PCBA in the production process, to use solder paste, solder, solder wire for welding, which the flux in the welding operation will lead to residues on the surface of the PCBA pollution, is the most important pollutant;.

3.Manual welding will lead to hand prints. Wave soldering welding operations will appear . Lots of wave soldering claw foot prints and welding tray (jig) prints. The PCBA surface may also have a certain degree of other types of contaminants, such as plugging holes in the adhesive, high-temperature adhesive tape residue glue, hand prints and dust, etc.; 4, the dust of the working environment, the working environment, dust.

4.The dust of the working environment, water and solvent vapors, smoke, tiny particles of organic compounds, and its electrostatic charged particles caused by PCBA are attached to the environmental pollution.

What are the ways to clean the circuit board?

1. Compressed Air
One of the safest cleaning agents for working on circuit boards is compressed air since you can remove rust from a distance. It can also remove any extra dust or debris from your circuit board since you are using high-pressure air.

2. Baking Soda
Since baking soda contains sodium bicarbonate, it even works on tough grime and breaks down the corrosion into smaller pieces. You can then easily clean all the corrosion and debris from your circuit board.

3. Distilled Water
Instead of using tap water, it is recommended to use distilled water for cleaning circuit boards since it does not damage any of the components of your circuit board. This can be great for cleaning your circuit board after you have used a chemical-based cleaning agent.

4. Isopropyl Alcohol
Speaking of chemical-based cleaning agents, isopropyl alcohol or rubbing alcohol can remove all kinds of dirt, debris, flux, and rust from your circuit boards. It is recommended to go with 90% isopropyl alcohol for cleaning circuit boards since it offers the best results.

A Step-by-Step Guide on How to Clean a Circuit Board

Step 1: Disassemble your equipment- The first thing you need to do is disassembling your gadget with a screwdriver to access the PCB. You may also need to detach cables from the PCB. If you are not well familiar with the device’s assembly, take pictures to assist you in the reassembling process.

Step 2: Make a cleaning solution by mixing baking soda and distilled water- You need a quarter cup of distilled water and two tablespoons of baking soda. Mix them until you get a thick paste.

Step 3: With the help of a PCB cleaning brush, start cleaning your board with the solution you made in step 2. Gently apply the mixture to each corroded part and give it 30 minutes to dry.

Step 4: After your cleaning reagent has dried, rinse it well with distilled water.

Step 5: Apply a phosphate-free household cleaner on your PCB and allow it to be still for about 15 minutes. With the help of the cleaner and a PCB brush, remove all remaining corrosions.

Step 6: Use a lint-free towel to clean off all remaining debris and water droplets/moisture. Do not wipe it down to avoid creating scratches.

Step 7: Preheat your oven to 1700, switch it off, and place the PCB inside for almost three hours to dry any remaining moisture.

Step 8: Reassemble your PCB and test whether it is properly functioning.