The circuit board is only a compound from the manufacture of a layer of copper foil.For non-functional circuit troubleshooting or bad performance, engineers can usually run simulation or other analysis tools from a matter of schematic circuit, so in order to avoid the impurities in the pcba board affect the short circuit boards, degradation and beautiful, need to clean them to pcba board, the circuit board of oil and other factors that affect printing and etching after removed.Then start printing the protective film on it.What’s left is the circuit.The excess is removed with a caustic acid and base.In the wash.For future anti – welding paint and paint printing.
Many people think that there will be a lot of foam in the process of cleaning, which will often affect the efficiency of the PCBA board cleaning process. In such cases, the solution is: use the defoaming agent or tianxingjian defoaming machine to deal with the foam.However, I personally think it is better to choose the latter, because the latter has the advantage of improving product yield.
Some boards are marked as free of cleaning, but in the FASTPCBA factory it is considered that free of cleaning should also be cleaned. According to the current standard, the word “free of cleaning” means that the residue of the board is chemically safe, will not have any impact on the board and can stay on the board.Corrosion, SIR, electromigration, and other specialized detection methods are mainly used to determine the halogen/halide content, and thus to determine the safety of the non-cleaned assembly pieces after assembly.
However, even with the use of a low-solid, non-cleaning flux, there will still be more or less residue, and for products with high reliability requirements, no residue or contaminants are allowed on the circuit board.For military applications, even disposable electronic assemblies are required to be cleaned.
When do you need to clean the circuit board?
1. Need for three protective coatings.Resin residues that are not cleaned before surface coating can lead to lamination or cracks in the protective layer;The surfactant residues may cause electrochemical migration beneath the coating, resulting in the failure of the coating’s rupture protection.The study shows that the adhesive rate of coating can be increased by 50% by cleaning.
2. Appearance and electrical performance requirements.The most direct impact of PCBA pollutants is the appearance of PCBA. If it is placed or used in a high-temperature and high-humidity environment, the residual moisture absorption and whitening may occur.As a large number of lead-free chips, miniature BGA, chips-level packages (CSP) and 01005 are used in the components, the distance between the components and the circuit board is reduced, the size is miniaturized, and the assembly density is increasing.If the halide is hidden below the element and cannot be cleaned, local cleaning may result in disastrous consequences due to the release of the halide.
The above is the professional knowledge provided by FASTPCBA, Hope can help you!
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