Friends who have been in the placement factory know that the general PCB will be baked in the oven before placement (except for special plates). What is the use of this? Next, the editor will analyze them one by one for everyone.

In the production process of SMT chip processing, there are many details that need to be paid attention to by the chip processing plant and implemented in the processing and production process. Baking the long-term stored PCB before processing is one of them. The purpose of baking the PCB is mainly to remove moisture and moisture. If the PCB stored for a long time is not in a vacuum package state, it will inevitably come into contact with the air, and the water molecules contained in the air are the key factors affecting the circuit board.

When the content of water molecules exceeds the relevant regulations and enters the reflow furnace, wave soldering furnace, hot air leveling or hand welding process above 200 ℃ during the SMT chip processing or welding process, the internal water Molecules will be heated and atomized into water vapor. As the temperature rises, the volume of water vapor will expand rapidly. When the temperature is higher, the volume of atomization will increase. At this time, when the water vapor cannot be removed from the board immediately If it escapes from the inside, it has a good chance to expand the PCB and break the vias between the layers of the circuit board. Sometimes it may cause the separation of the PCB layers, and even the surface of the circuit board can be seen more seriously. Phenomenon such as blistering, swelling, and cracking, sometimes even if the above phenomenon is not visible on the outside of the PCB, it is actually internally injured. Over time and aging will cause the function of electrical products to become unstable and eventually cause product failure.

And during the baking process, there are also places that need to be paid attention to. For example, the PCB after baking is deformed. Such a board will have offset or uneven thickness during the solder paste printing process of the PCBA patch. , Which will cause a large number of welding short-circuits or empty welding and other defects during the subsequent reflow.