“Cleaning” is often overlooked during board (PCB) PCBA manufacturing and is considered to be 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 caused many failures, and the rework or recall of the product caused a sharp increase in operating costs. Below, Heming Technology will briefly explain the role of PCBA cleaning of circuit boards (circuit boards).
PCBA (Printed Circuit Assembly) has a number of process stages in the production process, and each stage is contaminated to varying degrees. Therefore, various deposits or impurities are left on the surface of the PCB of the circuit board (circuit board), which will reduce the performance of the product. And even caused the product to fail. For example, in the process of soldering electronic components, solder paste, flux, etc. are used for auxiliary soldering, and residues are generated after soldering, and the residue contains organic acids and ions, etc., in which organic acids corrode the circuit board (circuit board) PCBA, and The presence of electrical ions can cause short circuits and cause product failure.
There are many kinds of contaminants on PCB (PCB) PCBA, which can be classified into two types: ionic and non-ionic. The ionic pollutants are exposed to moisture in the environment, and electrochemical migration occurs after energization, forming a dendritic structure, resulting in a low resistance path and destroying the PCBA function of the circuit board (circuit board). Non-ionic contaminants can penetrate the insulating layer of PC B 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, floating spots in solder baths, dust, dust, etc. These contaminants can lead to reduced solder joint quality, sharp solder joints during soldering, and Porosity, short circuit and many other undesirable phenomena.
With so many pollutants, which ones are the most concerned? Fluxes or solder pastes are commonly used in reflow and wave soldering processes. They are mainly composed of solvents, wetting agents, resins, corrosion inhibitors and activators. Thermally modified products must be present after soldering. In all the pollutants, the post-weld residue is the most important factor affecting the quality of the product. The ionic residue tends to cause electromigration to reduce the insulation resistance, and the rosin resin residue is easy to adsorb. Dust or impurities cause an increase in contact resistance, and in severe cases, open circuit failure, so strict cleaning must be performed after welding to ensure the quality of PCBA of the circuit board (circuit board).
In summary, the cleaning of the circuit board (PCB) PCBA is very important, and “cleaning” is an important process that is directly related to the quality of the PCB (circuit board) PCBA, which is indispensable.