PCB の保存期間

After completing the final product inspection, we will vacuum-pack the PCB boards and store them for shipping once confirmed without any issues. But why do PCB boards need vacuum packaging? How should they be stored after vacuum packaging? And what is their shelf life? Here is a brief overview from PCBWay about the storage methods and shelf life of PCB boards.

Why do PCBs Need Vacuum Packaging?

While this question may seem trivial, PCBWay takes it very seriously. There are several important reasons why PCB boards need to undergo vacuum packaging:

• Oxidation Prevention: PCB boards often feature delicate surface treatments like immersion gold, immersion tin, or immersion silver. These surface treatments are susceptible to oxidation when exposed to air and moisture for extended periods. Vacuum packaging creates a sealed environment, preventing the ingress of air and moisture, thereby preserving the integrity of the surface treatments and preventing oxidation.

• Moisture Control: High humidity can potentially damage the performance and reliability of PCBs. Excessive humidity can lead to condensation, which may result in short circuits or corrosion of sensitive components. Using suitable desiccants or moisture-absorbing materials for vacuum packaging helps maintain a dry environment and prevents moisture-related issues.

• Avoid Contamination: Airborne dust, particles, and contaminants can deposit on PCBs, causing potential electrical shorts or performance degradation. Vacuum packaging creates a barrier that prevents contaminants from depositing on the board's surface, thereby maintaining its quality.

• Long-Term Storage: In various industries, PCBs may need to be stored for a period of time before being assembled into the final product. Vacuum packaging extends the shelf life of PCBs by protecting them from environmental factors that could lead to deterioration over an extended period, ensuring their quality is preserved.

The PCBWay manufacturing factory vacuums and seals the circuit boards perfectly. Let's take a brief look at it through a video.

How to Store PCBs?

• Environmental Control: Store PCB boards in an environment with stable temperature and suitable humidity to prevent damage caused by temperature and humidity fluctuations. The recommended storage temperature is 15°C to 30°C, with a relative humidity of 40% to 65%.

• Moisture Avoidance: PCB boards are sensitive to humid environments, so it is important to avoid storing them in high-humidity areas. You can use desiccants or humidity control equipment to maintain the appropriate humidity levels.

• Dust Protection: PCB boards should be shielded from contact with dust and dirt, so the storage environment should remain clean. You can use covers or packaging to prevent dust from entering.

• Avoid Sun Exposure: PCB boards should be shielded from prolonged exposure to direct sunlight to prevent material aging and degradation. 

• Proper Packaging: Unused PCB boards can be packaged using anti-static bags, foam sheets, etc., to protect them from mechanical and environmental damage.

• Handle with Care: When handling and storing PCB boards, handle them carefully to avoid damaging the PCBs or their packaging.

• Clear Labeling: Label stored PCB boards with information such as model, batch, and storage date to facilitate tracking and management.

• Regular Inspection: Periodically inspect stored PCB boards to ensure their packaging is intact and free from moisture, contamination, or other issues.

In the IPC-1601 standard, the classification of the shelf life of PCBs with different surface treatments is as follows:

Explanation of the Shelf Life for FPC Boards

• The exposed portions of FPC conductors must undergo surface coating treatments such as gold plating, OSP, immersion tin, or immersion silver. Storage conditions should avoid corrosive gases, with temperature controlled below 25°C and humidity maintained at 50-70%.

• Under the above storage conditions, FPCs with gold plating have an effective shelf life of 6 months from the date of manufacture. When vacuum-sealed with desiccants, the shelf life extends to 1 year. FPCs with surface treatments like immersion silver, immersion tin, OSP and others typically have a storage period of 3 months.

• Products beyond their shelf life will only affect soldering, with no other adverse effects.

• The substrate materials used in FPCs have moisture-absorbing properties. If the customer's process involves high temperatures or SMT processes, it is recommended to perform a moisture removal process through baking before operations to prevent issues such as blowholes, bubbles, and delamination in the product.

PCB Assembly Shelf Life

The shelf life of PCB assemblies (PCBA) refers to the duration during which the assembled electronic components on the PCB are expected to remain functional and reliable when stored under specified conditions.  The shelf life can vary depending on factors such as the type of components used, the manufacturing process, and the storage conditions.  Here are some key points to consider regarding the shelf life of PCB assemblies:

Components: The shelf life of a PCBA can be influenced by the individual components used in the assembly.  Each component may have its own shelf life specified by the manufacturer, which can vary based on factors like the type of component (e.g., integrated circuits, capacitors, resistors), packaging, and storage conditions recommended by the manufacturer.

Moisture Sensitivity: Some electronic components, particularly surface-mount devices (SMDs), are sensitive to moisture.  They are typically labeled with a moisture sensitivity level (MSL), which indicates the time limit for which they can be exposed to moisture before reflow soldering.  If the MSL is exceeded, the components may require baking or reconditioning before use, and their shelf life may be affected.

Solderability: Over time, the solderability of electronic components and PCB pads can degrade, affecting the quality of solder joints.  This degradation can be influenced by factors such as the type of surface finish on the PCB (e.g., HASL, ENIG), storage conditions, and exposure to contaminants.  Proper storage, handling, and periodic testing can help ensure the solderability of PCBA.

Storage Conditions: The shelf life of PCB assemblies can be extended by storing them under appropriate conditions.  Factors such as temperature, humidity, exposure to light, and protection from contaminants should be considered.  Components and assemblies are often stored in controlled environments with temperature and humidity controls to minimize the risk of degradation.

It's important to note that the specific shelf life of a PCBA may vary depending on the aforementioned factors and the specific requirements of the application.  It is recommended to consult the component manufacturers, assembly guidelines, and industry standards (such as IPC standards) for more detailed information on the shelf life and storage recommendations for PCB assemblies.

PCBWay PCB Assembly (PCBA) warranty period:

Manual mounting generally 3 months warranty period

The warranty period of machine mounting is generally 6 months to 12 months