Is It Important To Clean The Circuit Board Before PCBA Processing?

"Cleaning" is often overlooked in the PCBA manufacturing process of the circuit board, and it is considered that cleaning is not a critical step. However, with the long-term use of the product at the client, the problems caused by the ineffective cleaning in the early stage caused many failures, and the repair or recall of the product caused a sharp increase in operating costs. Now Tecoo and everyone discuss the role of PCBA cleaning of circuit boards.

There are multiple process stages in the PCBA production process, and each stage is polluted to different degrees. Therefore, various deposits or impurities remain on the surface of the PCBA of the circuit board. These pollutants will reduce 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, and residues are generated after soldering. The residues contain organic acids and ions, among which organic acids will corrode the circuit board PCBA, and the existence of ions may cause a short circuit.

There are many kinds of pollutants on the circuit board PCBA, which can be classified into two categories: ionic and non-ionic. When ionic pollutants come into contact with moisture in the environment, electrochemical migration occurs after electrification, forming dendritic structures, resulting in low-resistance paths and destroying the function of the circuit board. Non-ionic contaminants can penetrate the insulating layer of the PCB and grow dendrites under the surface of the PCB. In addition to ionic and non-ionic contaminants, there are also particulate contaminants, such as solder balls, floats in solder baths, dust, dust, etc., which can lead to poor solder joint quality, solder joint sharpening during soldering, resulting in Air holes, short circuits and many other undesirable phenomena.

With so many pollutants, which ones are the most concerned? Flux or solder paste is commonly used in reflow and wave soldering processes. They are mainly composed of solvents, wetting agents, resins, corrosion inhibitors and activators. There must be thermally modified products after soldering. These substances It dominates all pollutants. In terms of product failure, post-weld residues are the most important factor affecting product quality. Ionic residues can easily cause electromigration and reduce insulation resistance, and rosin resin residues are easy to adsorb. Dust or impurities will cause the contact resistance to increase, and in severe cases, the open circuit will fail. Therefore, strict cleaning must be carried out after welding to ensure the quality of the circuit board PCBA. Therefore, "cleaning" is an important process directly related to the quality of the circuit board PCBA, which is indispensable.