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.
Baking can eliminate the internal stress of the PCB, which is to stabilize the size of the PCB. The baked board has a relatively large improvement in warpage.
Advantages of baking: After baking, the moisture in the pad can be dried, the welding effect is enhanced, and the welding and repair rate are reduced.
Disadvantages of baking: The color of the PCB board may change, affecting the appearance.
The main purpose of PCB baking is to remove moisture and remove moisture from the PCB.
First, the specification of PCB management
1, PCB unpacking and storage
(1) PCB board seal can be directly used online within 2 months of unopened manufacturing date
(2) PCB board manufacturing date is within 2 months, the date of unpacking must be marked after unpacking
(3) PCB board manufacturing date is within 2 months, after opening, it must be used within 5 days.
2, PCB baking
(1) If the PCB is sealed and unsealed for more than 5 days within 2 months of the date of manufacture, please bake at 120 ± 5 °C for 1 hour.
(2) If the PCB is more than 2 months from the date of manufacture, please bake at 120 ± 5 °C for 1 hour before going online.
(3) If the PCB is more than 2 to 6 months from the date of manufacture, please bake at 120 ± 5 °C for 2 hours before going online.
(4) If the PCB is more than 6 months to 1 year before the date of manufacture, please bake at 120 ± 5 °C for 4 hours before going online.
(5) The baked PCB must be used within 5 days (input to IR REFLOW). After the bit is used, it needs to be baked for another hour before it can be used.
(6) If the PCB exceeds the manufacturing date of 1 year, please bake at 120 ± 5 °C for 4 hours before going online, and then send it to the PCB factory for re-spraying before it can be used.
3, PCB baking method
(1) Large PCB (16 PORT and above including 16 PORT), placed in a flat format, with a maximum of 30 sheets in a stack, and the oven is opened within 10 minutes after baking. The PCB is placed in a flat and natural cooling (requires pressure to prevent the bay fixture)
(2) Small and medium-sized PCB (8PORT below 8PORT) is placed flat, the maximum number of stacks is 40 pieces, the number of uprights is not limited, the oven is opened within 10 minutes after baking, and the PCB is placed flat and naturally cooled (requires pressure protection) Banwan fixtures)
Second, the 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 manufacturing process of the PCB manufacturer, but also have a great relationship with the region.
The PCB made by the OSP process and the pure immersion gold process generally has a shelf life of 6 months after packaging, and is generally not recommended for the OSP process.
The storage and baking time of PCB has a great relationship with the area. The humidity in the south is generally heavier. Especially in Guangdong and Guangxi, there will be “returning to the south” weather every year in March and April. It is very wet at this time. The PCB must be used up within 24 hours of exposure to air, otherwise it will be easily oxidized. After normal opening, it is best to use up to 8 hours. For some PCBs that need to be baked, the baking time is longer. In the northern regions, the weather is generally dry, the PCB storage time will be longer, and the baking time can be shorter. The baking temperature is generally 120 ± 5 ° C baking, baking time is determined according to the specific circumstances.
If you need to know more about PCB drying and PCB-baked-machine machin, please contact us.
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