“Cleaning” is often ignored in the PCBA manufacturing process of circuit boards, and it is considered that cleaning is not a critical step. However, with the long-term use of the product on the client side, the problems caused by the ineffective cleaning in the early stage cause many failures, repair or The recalled products have caused a sharp increase in operating costs. Below, Heming Technology will briefly explain the role of PCBA cleaning of circuit boards.
The production process of PCBA (printed circuit assembly) goes through multiple process stages, and each stage is polluted to different degrees. Therefore, various deposits or impurities remain on the surface of the circuit board PCBA. These pollutants will reduce the product Performance, and even cause product failure. For example, in the process of soldering electronic components, solder paste, flux, etc. are used for auxiliary soldering. After soldering, residues are generated. The residues contain organic acids and ions. Among them, organic acids will corrode the circuit board PCBA. The presence of electric ions may cause a short circuit and cause the product to fail.
There are many kinds of pollutants on the circuit board PCBA, which can be summarized into two categories: ionic and non-ionic. Ionic pollutants come into contact with moisture in the environment, and electrochemical migration occurs after electrification, forming a dendritic structure, resulting in a low resistance path, and destroying the PCBA function of the circuit board. Non-ionic pollutants can penetrate the insulating layer of PC B and grow dendrites under the surface of the PCB. In addition to ionic and non-ionic pollutants, there are also granular pollutants, such as solder balls, floating points in the solder bath, dust, dust, etc. These pollutants can cause the quality of solder joints to be reduced, and the solder joints are sharpened during soldering. Various undesirable phenomena such as pores and short circuits.
With so many pollutants, which ones are the most concerned? Flux or solder paste is commonly used in reflow soldering and wave soldering processes. They are mainly composed of solvents, wetting agents, resins, corrosion inhibitors and activators. Thermally modified products are bound to exist after soldering. These substances In terms of product failure, post-welding residues are the most important factor affecting product quality. Ionic residues are likely to cause electromigration and reduce insulation resistance, and rosin resin residues are easy to adsorb Dust or impurities cause the contact resistance to increase, and in severe cases, it will lead to open circuit failure. Therefore, strict cleaning must be carried out after welding to ensure the quality of the circuit board PCBA.
In summary, the cleaning of the circuit board PCBA is very important. “Cleaning” is an important process directly related to the quality of the circuit board PCBA and is indispensable.