PCB Technical - Introduction to PCB storage and baking time

Introduction to PCB storage and baking time

Friends in the PCB industry know that after the PCB is completed, there is a shelf life. If the shelf life is exceeded, the PCB must be baked, otherwise the PCB will be prone to bursting when the smt is on line.

The preservation time of PCB and the temperature and time of baking PCB are all regulated by the industry. What is this specification, let's look at it together.

One, PCB management and control specifications

1. PCB unpacking and storage
   (1) Sealed and unopened, if the manufacturing date is within 2 months, it can be directly used online
   (2) The manufacturing date is within 2 months, and the unpacking date must be marked after unpacking
   (3) The manufacturing date is within 2 months, and it must be online and used within 5 days after unpacking

2, PCB baking
(1) If sealed and unpacked for more than 5 days within 2 months of the date of manufacture, bake at 120±5°C for 1 hour
(2) 2 months after the date of manufacture, baking at 120±5 degree Celsius for 1 hour before going online
(3) 2 to 6 months after the manufacturing date, baking at 120±5 degree Celsius for 2 hours before going online
(4) 6 to 12 months after the date of manufacture, baking at 120±5°C for 4 hours before going online
(5) PCBs that have been baked must be used up within 5 days (put into IR REFLOW), and unused PCBs must be baked for another hour before they can be used online.
(6) One year after the manufacturing date, baking at 120±5 degree Celsius for 4 hours before going online, and then sending it to the PCB factory for re-spraying tin before going online.

3, PCB baking method
(1) Large PCBs (16 PORTs and above, including 16 PORTs) are placed horizontally, a stack of up to 30 pieces, open the oven within 10 minutes after the baking is completed, take out the PCB, and place it horizontally to cool down (need to press the anti-plate bay fixture)
(2) Small and medium-sized PCBs (8PORTs and below 8PORTs) are placed horizontally. The maximum number of a stack is 40 pieces. The number of vertical type is not limited. Open the oven within 10 minutes after the baking is completed. Banwan fixture)

2. Preservation and baking of PCBs in different regions

The specific storage time and baking temperature of 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.
The PCB made by OSP process and pure immersion gold process has a shelf life of 6 months after packaging. It is generally not recommended to bake for OSP process.
The preservation and baking time of PCB has a lot to do with the region. The southern part has heavier humidity, especially in Guangdong and Guangxi. In March and April each year, there will be "returning to the south" weather, with continuous rainy and very humid weather. . PCB exposed to the air must be used up within 24 hours, otherwise it is easy to oxidize. After normal opening, it is best to use it up in 8 hours. For some PCBs that need to be baked, the baking time will be longer. In the northern regions, the weather is generally dry, the PCB storage time will be longer, and the baking time can also be shorter. The baking temperature is generally 120±5 degree Celsius, and the baking time is determined according to the specific situation.

Regarding PCB storage time, baking time and temperature, you should not memorize it by rote, but specific analysis of specific problems. It needs to be specific based on the PCB board and control specifications, according to the production capacity, process, region and season of different manufacturers choose.