1. What is the white spot problem often mentioned in PCBA processing

　　Some PCBA processed products may encounter the problem of white spots? White spots generally occur during the soldering process or the post-solder cleaning process, and are mainly manifested as white spots or white residues on or around the surface of the PCB, pins and solder joints. pcba OEM and electronic materials purchase structural parts to produce SMT processing, PCBA manufacturing, complete machine assembly, complete machine testing, with a strong engineering team, providing a complete set of IT structure and supply chain and scientific quality management system, committed to Meet different types of manufacturing requirements of OEMs/customers. The composition of vitiligo substances can be reactive substances such as crystalline rosin, rosin mutants, organic and inorganic metal salts, radical fluxes, fluxes or cleaners, and other chemicals produced during high temperature soldering. However, most rosin or water-soluble acids are chemically altered from the flux, making them more difficult to dissolve in cleaning agents than their original ingredients.

　　Generally, pine resin residues can be cleaned and removed by selecting different solvent combinations to achieve swelling and dissolution according to similar dissolution principles and dissolution coefficients. However, organic acids react with metals such as tin and lead and their metal oxides to form carboxylates, and the higher the temperature, the longer the formation time. This hard metal salt cannot be removed by general solvents and requires ultrasonic-assisted cleaning. Therefore, the generation of such residues can be reduced by lowering the temperature and shortening the time. In addition, the denaturation of organic matter after soldering brings difficulties to cleaning the composition of the flux. In addition, there are many types of PCB fluxes, which are chemically interfered in the PCB production process. The intervention of some solvents in the flux destroys the original surface quality of the flux. The phenomenon of vitiligo emerges in an endless stream, only targeted selection of cleaning agents. In view of the existence of various types of vitiligo in PCBA processed products, which have a certain impact on product quality, it is necessary to find out the reasons for different types of vitiligo. White spots appear in wave and reflow soldering. The composition of vitiligo is very complex, and its causes are not easy to predict. Due to the complexity of wave soldering process control and the difficulty of white spot identification, the quality of wave soldering can be determined by the following steps in the production process.

　　PCB circuit board patch

　　PCB circuit board patch

　　2. Identification method of white spot components in PCBA processing

　　① Welding logo repeats the flux logo, but skips the wave soldering step. If there is no white spot, it is related to too high soldering temperature or too long soldering time.

　　②Cleaning agent/cleaning process identification

　　After standard assembly processes, PCBA processing extends the time interval between soldering and cleaning until the temperature drops to room temperature. If there are no white spots, the problem is related to the cleaning process temperature.

　　③PCB Identification Remove several unplugged bare boards from the problem batch and pre-wash with the usual cleaning procedure for flux removal. Pre-washed bare boards are cleaned after the standard assembly process. If the pre-washed board goes through the same procedure without white spots, the problem is that the light board is contaminated. Confirm whether there is any problem with the manufacturing process of the light plate.

　　④Flux identification Take out a few uninserted bare boards from the problem batch, do not add flux, but follow the standard assembly process. OEM has a group of high-quality management personnel and skilled employees, and has international advanced production equipment and complete testing technology and scientific quality management system, committed to meeting the needs of OEM manufacturers/customers of different types. Manufacturing requirements, provide a full range of services from product component procurement to production assembly and technical support. If there are no white spots, the problem is with the flux and solder.

　　⑤Other reasons To identify other reasons for the residue on the surface of PCBA processing, it can be detected by optical methods, and it can also be observed by solvents such as dripping water or ethanol. If it dissolves in water, it is expressed as an inorganic residue, if it dissolves in alcohol, it is expressed as an organic residue. Types, causes, and cleaning methods of PCBA vitiligo Conventional PCBA cleaning methods may have limited impact on some of the refractory vitiligo covered in this article.

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