What is the shelf life of PCB? And how about the baking time and temperature?

After the manufacturing of PCB circuit boards, there is a shelf life, beyond which the PCB needs to be baked, otherwise it is easy to cause the problem of PCB board bursting when the SMT is put on line for production.

The storage time of PCBS, as well as the temperature and time used to bake PCBS in an industrial oven are all regulated by the industry.

One, PCB control specifications.

1. PCB unpacking and storage.

(1) PCB board can be directly put into use within 2 months of the manufacturing date without unpacking.

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

(3) The manufacturing date of PCB board shall be within 2 months, and the PCB board shall be put into use 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 is more than 2 months after the manufacturing date, please bake it at 120 ±5℃ for 1 hour before going online.

(3) If the PCB is more than 2 to 6 months after the manufacturing date, please bake it at 120 ±5℃ for 2 hours before going online.

(4) If the PCB is more than 6 months to 1 year after the manufacturing date, please bake it at 120 ±5℃ for 4 hours before going online.

(5) The baked PCB shall be used within 5 days (put into IR REFLOW), and the PCB shall be baked for another 1 hour before it can be used on line.

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

3. PCB baking method.

(1) Large PCB (16 PORT or above including 16 PORT) shall be placed flat, with a maximum number of 30 pieces in a stack. After baking, open the oven within 10 minutes, take out the PCB and place it flat for natural cooling (pressure proof board bay fixture).

(2) Small and medium-sized PCB (including 8PORT below) is placed flat, a maximum of 40 pieces in a stack, the number of upright is not limited, after baking 10 minutes open the oven to take out the PCB flat natural cooling (pressure anti-board bay governing equipment).

Tow. Preservation and baking of PCB in different regions.

The specific storage time and baking temperature of PCB are not only related to the production capacity and production process of PCB manufacturers, but also have a great relationship with the region.

The shelf life of PCB made by OSP process and pure gold sinking process is generally 6 months after packaging. Baking is not recommended for OSP process.

PCB preservation and baking time has a great relationship with the region, in the south of the general humidity is relatively heavy, especially in Guangdong and Guangxi, in March and April every year there will be a "south day" weather, rainy every day, at this time is very humid. PCB must be used up within 24 hours after exposure to air, otherwise it is easy to oxidize. After normal opening, 8 hours is the best. For some PCBS that need to be baked, the baking time is longer. In the northern region, the weather is generally dry, PCB storage time is longer, baking time can also be shorter. Baking temperature is generally 120 ±5℃ baking, baking time according to the specific situation to decide.

For the preservation time, baking time and temperature of printed boards, it is necessary to analyze the specific problems. Based on the PCB management and control specifications, specific choices are made according to the production capacity, process, region and season of different manufacturers.