Assembly – Welding parts to plates may leave contamination; As a flux residue, therefore, the copper trace is subjected to surface treatment during the manufacturing process, which is then cleaned.

Transport – whether it is from a contract manufacturer (CM) to you, or from a customer or customer, your PCB can be affected by unstable high temperatures – which can cause humidity or low temperatures – which can cause cracking and lead to breakage. One way to guard against these threats is to protect the circuit board with conformal coatings or other types of packaging.

Storage – After operation, your board will probably spend the most time on storage. If your CM is not, parts may be turnkey manufacturing service providers between fabrication and assembly, but most will be done after assembly. Therefore, it is necessary to follow good PCB storage guidelines to ensure that your boards are ready for use when they are ready.

You should know about PCB storage knowledge

Unprotected storage of bare (PCB) or assembled (PCBA) can spell disaster. Also, if remanufacturing costs, undelivered and potentially canceled deliveries start eating into your rate of return, it’s a valuable lesson to learn not to recognize that if left unprotected, your circuit boards will degrade faster and faster over time. Fortunately, there are remedies that, if applied, can greatly reduce the likelihood of losing any boards due to improper handling or poor storage habits.

The first step is to make sure your CM follows good board handling and storage recommendations; Example in IPC-1601 printed board handling and storage guidelines. These guidelines provide manufacturers and assemblers with methods and information to protect PCBS from:

pollution

Reduced weldability

Physical damage

Absorb the moisture

Electrostatic discharge (ESD)

Combined with IPC/JEDEC J-STD-033D IPC-1601 handling, packaging, transportation and use of moisture, reflow soldering and process-sensitive equipment, the IPC provides standards for packaging and storage to minimize the possibility of contamination of the circuit board during manufacturing. In addition, the accompanying shipping and storage guidelines and understanding of product implications can be used. The shelf life of the assembled PCB compiles a set of important PCB storage criteria, as shown below.

Important PCB storage guidelines

Apply proper surface finish during manufacture

Bare boards may require temporary storage after manufacture but before assembly. To prevent oxidation and contamination during this period, suitable surface treatments should be used.

If possible, use non-wet components

Water insensitive SMD components have virtually unlimited storage life at temperatures ≤30°C (86°F) and relative humidity (RH) ≤ 85% prior to assembly. If packaged correctly, these components should easily exceed the nominal shelf life of 2-10 years after assembly. Moisture sensitive components, on the other hand, have a recommended shelf life of one day to one year of pre-assembly. For a circuit board with these components, the environmental control and storage containers will largely determine its viability.

Store the board in a moisture-proof bag (MBB) with desiccant

All boards should be stored in moisture-proof bags to prevent moisture from entering the bags and to prevent desiccant from absorbing moisture inside. However, do not use bags that have been stored for more than a year.

Vacuum sealed MBB

MBB shall be dried and vacuum-sealed. This will provide anti-static protection.

Control environment

Care should be taken to ensure that there are no extreme temperature fluctuations during storage or transportation, as temperature differences can cause water transfer or condensation. The best choice is at a controlled temperature of ≤30°C (86°F) and 85% RH.

Ship or use the oldest boards first

It’s also a good idea to always ship first or use older boards to maximize avoiding forgetting boards and exceeding the recommended shelf life.