PCB Storage Humidity Standards

A PCB (Printed Circuit Board) is also known as a printed circuit board or printed wiring board in Chinese. It is a type of substrate made using electronic printing technology, serving as a support for electronic components and providing circuit connections for them. PCBs are typically made from insulating boards cut to specific dimensions, featuring at least one conductive pattern and holes (such as component holes, fastener holes, and plated through-holes). They replace the traditional chassis for mounting electronic components and enable interconnections between them. As a critical component in electronic devices, the performance and stability of PCBs are essential to the overall operation of the equipment. Storage humidity is a key factor affecting the performance and stability of PCBs, as improper humidity levels can lead to moisture absorption, oxidation, corrosion, and other issues.

I.Humidity Standards for PCB Storage

The PCB storage humidity standard refers to the range of humidity levels that must be maintained during the storage of PCBs. To ensure the performance and stability of PCBs, the standard humidity range is typically 20% to 60%. Within this range, PCBs do not exhibit significant performance degradation or quality issues. For PCBs used in special applications, such as high-precision or high-temperature environments, the storage humidity standard may vary.

1. Preventing Moisture Absorption:​ Moisture absorption is a common issue in PCB materials, particularly in high-humidity environments. If humidity exceeds the standard range, PCBs may absorb moisture, leading to electrical performance degradation, short circuits, oxidation, and other problems.
2. Preventing Oxidation and Corrosion:​In high-humidity environments, metal components are prone to oxidation and corrosion, which can reduce the reliability and lifespan of PCBs.
3. Maintaining Stability:​Humidity fluctuations can cause changes in the dimensions and shape of PCB materials, potentially leading to issues such as component spacing or pin spacing, which may affect the normal operation of circuits.

II.Effects of Humidity on PCBs

1. Oxidation:When PCBs are exposed to high-temperature and high-humidity environments, copper traces may oxidize, reducing their conductivity. Additionally, excessive humidity can accelerate the corrosion of other metal materials on the PCB.
2. Short Circuits and Open Circuits:Excessively low humidity can cause static electricity between traces on a PCB, leading to short circuits or open circuits. Conversely, excessively high humidity may result in the formation of a water film between traces, also causing short circuits or open circuits.
3. Degradation of Insulation Performance:Excessive humidity can cause cracks or bubbles in the insulating layer of a PCB, reducing its insulation performance. This may affect the normal operation of the circuit and even pose safety risks.

III.How to Control Storage Humidity

Using a dry cabinet to store PCBs offers functions such as dehumidification and oxidation prevention, providing a dry and stable storage environment for PCBs.

1. Dehumidification Capability of the Dry Cabinet:Choose a dry cabinet with strong dehumidification capabilities to ensure that the humidity of the storage environment remains at an appropriate level. The stronger the dehumidification capability, the better the moisture-proof effect.
2. Sealing Performance of the Dry Cabinet:The dry cabinet should have good sealing to prevent external moisture from entering. Poor sealing can allow moisture to penetrate, affecting the storage quality of PCBs.
3. Temperature and Humidity Control:When storing PCBs in a dry cabinet, it is important to control the temperature and humidity inside. The recommended temperature is 20–25°C, and the recommended humidity is 20%–60%. Improper temperature and humidity control may affect the performance and quality of the PCBs.
4. Regular Inspection and Maintenance:Regularly check the dehumidification effectiveness and sealing of the dry cabinet, and promptly clean any debris or dust inside. If any malfunctions or issues are detected, contact the manufacturer for repair or replacement as soon as possible.
5. Using Records and Labels:Assign a label or record for each PCB in the dry cabinet, noting its name, model, production date, and other relevant information. This facilitates management and tracking of PCBs, ensuring their storage quality and safety.

Storing PCBs in a dry cabinet is an effective moisture-proof measure, providing a dry and stable storage environment for the boards. During use, it is important to select a suitable dry cabinet, maintain its sealing and cleanliness, perform regular inspections and maintenance, and take other necessary precautions to ensure the storage quality and safety of the PCBs.