What Should We Pay Attention To When Clean Assembled PCB?

We need to know that during the PCB assembly production, solder paste and flux usually produce residual substances. The residue contains organic acids and decomposable ions. Among them, organic acids have corrosive effect, and the residual ions on the pads can cause short circuits. Moreover, these residues are dirty on the assembled PCB and do not meet the customer’s requirements for product cleanliness. Therefore, it is very necessary to clean the assembled PCB.

Assembled PCB should be cleaned as soon as possible after soldering. Since the flux residue gradually hardens over time and forms corrosives such as metal halides, it is necessary to thoroughly remove residual flux, solder and other contaminants from the PCB. Cleaning is the dissolution removal process of a solder residue. Its purpose is to extend the life of the product in essence by ensuring good surface resistance and preventing leakage. What should be paid attention to in PCBA cleaning?

When cleaning: Prevent harmful cleaning agents from entering the components that are not completely sealed to avoid direct or potential damage to the components.

After cleaning: PCBA should be placed in a 40~50 * C oven for 24 to 30 minutes.

The touching on device with naked hand is not applied until the cleaning parts is dried. Moreover, cleaning should not affect components, markings, solder joints, and PCBs. Generally, the PCB assembly of electronic products needs to go through the SMT+THT process, and it must also undergo wave soldering, reflow soldering, manual soldering and other soldering processes. Regardless of the type of soldering, the assembly (electrical assembly) process is the primary source of assembly contamination.

From the evolving electronics market, we can see that today’s and future electronic products will become more and more miniaturized, and the requirements for high performance and high reliability will be stronger than ever. Thorough cleaning work is a very important and technical that directly affects the working life and reliability of electronic products, as well as the protection of the environment and human health.

Therefore, we must re-understand and solve the welding cleaning problem from the perspective of the entire production process system. Not only the implementation of the solution should be matched with the use of soldering materials such as flux, solder paste, solder wire, etc., but also to match organic solvents, inorganic solvents and their mixed solvents or water washing.In this way, the residue of the PCB assembly can be effectively removed, making the cleanliness easier to meet customer expectation.