PCBA storage conditions and requirements

During the PCBA production process, several storage stages are required. After the SMT processing is completed before the DIP processing, it is often necessary to store a certain time. After the PCBA board test is completed, after the finished product assembly, there are often also have a period of storage, then what are the storage conditions and requirements?

1. Storage after SMT

Normally, after the SMT, it will be placed in the DIP workshop for 1-3 days, sometimes longer. For ordinary types of boards, the temperature is controlled between 22-30 ° C, the humidity is controlled between 30-60%, and the anti-static shelf is used. However, for the PCB board of the OSP process, need moisture-proof box to store, the temperature and humidity requirements are more strict, and the soldering is completed within 24 hours as much as possible, otherwise the pad is easily oxidized.

2. Storage after PCBA test is completed

Generally, after PCBA test is completed, the PCBA board will be assembled quickly, and in this case, the temperature and humidity are well controlled, and there is not much requirements. However, if it takes a long time to store, it can be coated with conformal coating, and vacuum-packed. The ambient temperature is controlled between 22-28 ° C and the relative humidity is 30-60%.

According to different surface processes, PCBA storage time also has an impact, as shown below:

Type	Surface	Storage condition	Storage period
HAL	Silver	1. Temperature: 22+/-4 ° C; 2. Relative humidity: 30-60%; 3. Vacuum-packed with desiccant	12 months
Immersion gold	Gold	1. Temperature: 22+/-4 ° C; 2. Relative humidity: 30-60%; 3. Vacuum-packed with desiccant	6 months
Immersion Tin	Silver	1. Temperature: 22+/-4 ° C; 2. Relative humidity: 30-60%; 3. Vacuum-packed with desiccant	3 months
Immersion Silver	Silver	1. Temperature: 22+/-4 ° C; 2. Relative humidity: 30-60%; 3. Vacuum-packed with desiccant	3 months
OSP	Gold	1. Temperature: 22+/-4 ° C; 2. Relative humidity: 30-60%; 3. Vacuum-packed with desiccant	3 months

In general, the PCBA board coated with conformal coating can extend the storage period by 3-9 months, but some PCBA boards are not suitable for conformal coating, it needs to be determined according to the actual situation of the product.