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Why PCB need to be baked

2020-06-29

Everyone who is engaged in the PCB manufacturing industry knows that copper-clad boards are covered with a piece of copper foil on the insulating material, and then baked. If you look closely, you will see that there will be shrinkage during the drying process, and stress in all directions will be generated. This is the source of the stress. Secondly, the purpose of the baking board before the PCB drilling is actually dehumidification. In order to remove the moisture in the board and reduce the internal stress; there is also printing resistance welding after the pressing, including characters, etc., need to be baked. There is also a baking platen process before shipping and packaging, which is also to remove moisture. The baked plate has a relatively large improvement in warpage.


 


The baking mentioned above can eliminate the internal stress of the PCB board, which stabilizes the size of the PCB. The most obvious advantage is that it can dry the moisture in the pad after baking, strengthen the welding effect, and reduce the virtual welding and repair rate. However, baking will cause a change in the color of the PCB board and affect the appearance.

 

Generally, 100-120 ° C for baking, about 2H for baking, don't bake too long time! If exposed to the air needs to be used up within a day, otherwise it is easy to oxidize.

 

1. If the PCB is sealed and unpacked for more than 5 days within 2 months of the manufacturing date, please bake at 120 ± 5 ℃ for 1 hour.

 

2. If the PCB exceeds the manufacturing date 2 months, please bake at 120 ± 5 ℃ for 1 hour before going online.

 

3. If the PCB exceeds the manufacturing date by 2 to 6 months, please bake at 120 ± 5 ℃ for 2 hours before going online.

 

4. If the PCB exceeds the manufacturing date from 6 months to 1 year, please bake at 120 ± 5 ℃ for 4 hours before going online.

 

5. The baked PCB must be used within 5 days (input into IR REFLOW), after the bit is used, it needs to be baked for another hour before going online.

 

6. If the PCB is more than 1 year after the manufacturing date, please bake at 120 ± 5 ℃ for 4 hours before going online, and then send it to the PCB factory to re-spray tin before going online. 


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