Why should PCB processing bake? Those engaged in PCB processing industry know that copper clad plate has a baking process in the process of processing into PCB circuit board, and the main purpose of PCB baking is to remove dampness Tide, remove the water gas contained or absorbed from the outside world, because some of the material used by PCB itself is easy to form water. Secondly, the purpose of PCB drying board before drilling is mainly dehumidification. PCB drying board before drilling is to remove the moisture in the plate, reduce the internal stress, and seal resistance welding behind the press, including characters need to be baked. Before shipping packaging, there is also the process of baking pressure plate, also in order to remove moisture, after the baked printed circuit board has a great improvement in warping.

The baking mentioned above can eliminate the internal stress of PCB circuit board, that is, to stabilize the size of PCB circuit board. Its most significant advantage is that it can dry the water in the welding pad after baking, strengthen the welding effect, reduce the virtual huang, repair rate and so on. However, baking will make a change in the PCB board color, and affect the appearance. Usually baking in general 100-120℃, baking about 2H, do not bake for too long! If exposed to the air in a day need to use up, otherwise it is easy to oxidation phenomenon, of course, this is not absolute, but also depends on the production capacity of PCB manufacturers, some OSis relatively a longer storage time. The following collar Ucreate on the PCB processing process of baking conditions and time setting instructions are as follows?

1. If the PCB is well sealed within 2 months of the manufacturing date, unsealed and placed in a temperature and humidity controlled environment (S30℃ / 60% RH, according to IPC-1601), it shall be baked at 120 ± 5℃ for 1 hour before launching.

2. The PCB is stored for 2~6 months after the manufacturing date, and it shall be baked at 120 ± 5℃ for 2 hours before launching.

3. Store PCB for 6~12 months, bake at 120 + 5℃ for 4 hours before launching,

4. PCB storage is more than 12 months, and it is basically not recommended, because the glue force of multilayer board will age with time, and quality problems such as product function instability may occur in the future, increasing the probability of market repair, and the production process also has the risk of poor plate blasting and tin eating. If it has to be used, it is recommended to bake at 120 + 5℃ for 6 hours first, and test print a large number of tin paste before production to determine that there is no solder problem before continuing production. Another is not recommended to use stored too long PCB because its surface treatment will gradually failure, with ENIG, the industry storage period for 12 months, after the limitation, depending on the thickness of the gold layer, thickness, if thin, the nickel layer may appear because of diffusion in the gold layer and form oxidation, influence trust, not careless.

5.All baked PCB must be used within 5 days, and the unadded PCB must be baked at 120 + 5℃ for another 1 hour before launching.

The baking time varies with the degree and size of the PCB, and the thin or large size PCR has to be pressed under the plate after baking, in order to reduce or avoid the tragedy of the bending deformation of the PCB due to the stress release during the cooling period after baking. Because of the daily deformation of PCB circuit board, there will be deviation or uneven thickness when SMT printing tin paste, which will cause a large number of welding short circuit or empty welding and other adverse occurrence during the back welding.