What is SMT?(十四) -- Assembly process -- Cooling after welding
author: Hellen
2022-10-13
A cooling station is usually added at the end of the wave soldering machine. To limit the tendency of copper-tin intermetallic compounds to form solder joints, another reason is to accelerate the cooling of the assembly and avoid board displacement when the solder is not fully cured. Rapid cooling of the assembly to limit the exposure of sensitive components to high temperatures. However, the hazards of thermal shock to components and solder joints from aggressive cooling systems should be considered. A well-controlled, "soft and stable", forced gas cooling system should not damage most components. There are two reasons for using this system: the ability to quickly handle the board without hand clamping, and the assurance that the component temperature is lower than the temperature of the cleaning solution. The concern is the latter reason, which may be the cause of some solder residue blistering. Another phenomenon is that sometimes there is a reaction with some flux float phenomenon, so that the residue "can not be cleaned off". There is no formula for ensuring that the data set up at the soldering station meets the requirements of all machines, all designs, all materials used, and the material conditions and requirements of the process. It is important to understand each step of the entire process.4 Conclusion In summary, to obtain the best solder quality and meet the needs of the user, it is necessary to control each process step before and during soldering, because each step of the entire assembly process of SMT is interrelated and interacts with each other, and a problem in any step will affect the overall reliability and quality. The same is true for the soldering operation, so all parameters, time/temperature, solder volume, flux composition and transfer speed should be strictly controlled. Defects in welding should be identified early, analyzed, and measures taken to nip in the bud the various defects that affect quality. In this way, we can ensure the production of products.
What is SMT?(十五) -- Failure reduction methods
What is SMT?(十三) -- Assembly process -- Wave peak
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