How long is the shelf life of PCB? And how to determine the baking time and temperature?

How long is the shelf life of PCB? And how to determine the baking time and temperature?

After the PCB is manufactured, there is a shelf life. If the shelf life is exceeded, the PCB needs to be baked. Otherwise, it is easy to cause the PCB to burst when the PCB is produced on the SMT line.

The storage time of PCB, and the temperature and time of using industrial oven to bake PCB are all regulated by the industry.

1. The specification of PCB control

1. PCB unpacking and storage

(1) PCB board sealed and unopened can be directly used online within 2 months of manufacturing date

(2) The PCB board manufacturing date is within 2 months, and the unpacking date must be marked after unpacking

(3) PCB board manufacturing date is within 2 months, after unpacking, it must be online and used within 5 days

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°C for 1 hour

(2) If the PCB is over 2 months from the manufacturing date, please bake it at 120 ±5°C for 1 hour before going online

(3) If the PCB is 2 to 6 months past the manufacturing date, please bake it at 120 ±5°C for 2 hours before going online

(4) If the PCB is 6 months to 1 year older than the manufacturing date, please bake at 120 ±5°C for 4 hours before going online

(5) The baked PCB must be used up within 5 days (put into IR REFLOW), and the PCB must be baked for another hour before it can be used online.

(6) If the PCB is more than 1 year from the manufacturing date, (remember that the upper part of the board needs to be protected with high-temperature kraft paper, the baking sheet is 2H, 120-150°C, when the temperature is reached, turn on the oven, press until the board is automatically cooled, and The board can be taken out for cleaning and used. (It needs to be pressed against the board bay fixture) , and then sent to the PCB factory for re-spraying tin before it can be used online

3. PCB baking method

(1) Large PCBs (16 PORTs and above, including 16 PORTs) are placed horizontally, with a stack of up to 30 pieces, (remember that the upper part of the board needs to be protected with high-temperature kraft paper, baking sheet 2H, 120-150°C When the temperature is reached, turn on the oven, press until the plate is automatically cooled, and then put the plate out for cleaning before use. (Need to press anti-Banwan jig) (Need to press anti-Banwan jig)

(2) Small and medium-sized PCBs (including 8PORTs below 8PORT) should be placed horizontally. The maximum number in a stack is 40 pieces. The number of upright types is not limited. A flat steel plate is required for the baking plate, and the flat surface is on the plate. (Remember the plate On the upper part, you need to use high-temperature kraft paper to protect the surface of the board. The baking sheet is 2H, 120-150°C. When the temperature is reached, turn on the oven, press until the board is automatically cooled, and then the board can be taken out for cleaning before use. (It needs to be pressed against the board bay. Fixture)

2. 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.

The PCB made by OSP process and pure immersion gold process generally has a shelf life of 3 months after packaging, and 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. In the south, humidity is generally heavier, especially in Guangdong and Guangxi. In March and April of each year, there will be a "return to the south" weather, which is cloudy and rainy every day. Continuously, it was very humid at this time. PCB must be used up within 24 hours when exposed to the air, 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℃, and the baking time is determined according to the specific situation.

management and control specifications, according to the production capacity, process, region and season of different manufacturers.