July 15, 2022
After the PCB is manufactured, it has a shelf life. If the shelf life is exceeded, the PCB needs to be baked. Otherwise, it is easy to cause the PCB to explode when the PCB is produced on the SMT line.
There are industry specifications for the storage time of PCBs, as well as the temperature and time for baking PCBs in industrial ovens. The details are as follows:
1. Unpacking and storage of the PCB
(1) The PCB board can be directly used online within 2 months of the unopened manufacturing date.
(2) The manufacturing date of the PCB board is within 2 months, and the unpacking date must be marked after unpacking
(3) The manufacturing date of the PCB board is within 2 months, and it must be used online within 5 days after unpacking
2. PCB baking
(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 by 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 by 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 (put into IR REFLOW), and it needs to be baked for another 1 hour before it can be used online.
(6) If the PCB exceeds the manufacturing date for 1 year, please bake it at 120±5℃ for 4 hours before going online, and then send it to the PCB factory for re-spraying before it can be used online.
3. PCB baking method
(1) Large PCBs (more than 16 PORT including 16 PORT) are placed horizontally, with a maximum number of 30 pieces in a stack. Open the oven within 10 minutes after baking, take out the PCB and lay it flat for natural cooling (requires anti-panwan fixtures)
(2) Small and medium-sized PCBs (below 8PORT including 8PORT) are placed flat. The maximum number of a stack is 40 pieces, and the number of vertical ones is not limited. Open the oven within 10 minutes after the baking is completed, take out the PCB, and place it flat and let it cool naturally.
Preservation and baking of PCBs in different regions
The specific storage time and baking temperature of the PCB are not only related to the production capacity and production process of the PCB manufacturer, but also have a great relationship with the region.
PCBs made by OSP process and pure immersion gold process generally have a shelf life of 6 months after packaging. Baking is generally not recommended for OSP process.
The preservation and baking time of PCB have a lot to do with the region. In areas with heavy humidity, it is rainy every day, and it is very humid at this time. The PCB must be used up within 24 hours after being exposed to the air, otherwise it is easy to oxidize. After normal opening, it is best to use it up within 8 hours. For some PCBs that need to be baked, the baking time is longer. In areas where the weather is relatively dry, the preservation time of the PCB will be longer, and the baking time can also be shorter. The baking temperature is generally 120 ± 5 ℃, and the baking time is determined according to the specific situation.
Regarding the storage time, baking time and temperature of the PCB, it is necessary to analyze the specific problems in detail. It is necessary to make specific choices based on the PCB management and control specifications, according to the production capabilities, processes, regions and seasons of different manufacturers.
Of course, if it is just an experiment, it can be adjusted between the room temperature of 25 and the extreme high temperature resistance of general electronic products of 120. It should be noted that in the electronics industry, it is generally calculated that the life is doubled for every 10 degrees. If it is a batch product, it means that after dipping the insulating varnish (drying insulating varnish), put it in the oven, the temperature is 80 degrees, and bake for 2 hours.
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