Printed Circuit Boards (PCBs) must be protected to bolster the integrity. If you are looking for the PCB storage options, this article teaches you what you need to know.
What is PCB Storage?
It refers to the method of protecting a Printed Circuit Board (PCB) and preventing the same from damages.
When it comes to the storage, it is done for different reasons. While the major reason is to protect the boards from the temperature, it can also be done to keep the boards safe when transported.
What are the Stages of PCB Storage?
You may not need to store or protect the boards if there is no need for that. Hence, being sure of when the storage is required is very important.
Here are some of the important moments or stages when you need to store and protect PCBs:
1. Store PCBs during the Fabrication Stage
Already fabricating the boards? Congratulations, but you need to beef-up on the protection. The fabrication stage is when the boards’ development commences in earnest. As such, you need to keep the boards safe from contaminants that would impede the performance once production is completed.
2. Store the PCB Post the Fabrication
Fabricating a board is one of the important steps to the production. But after that, the board has a post-fabrication stage and this is one of the crucial moments for the protection.
During the post-fabrication stage, especially when solder mask is applied, the board is susceptible to damages that affect the solder mask.
Here are some of the reasons why the board needs to be stored before the fabrication:
- Depending on the arrangement, the PCB manufacturer might collaborate with other companies to fabricate the board. Therefore, the transportation to and from these factories opens up the boards to excess moisture that eventually contaminate the boards.
- Storing the PCBs during the post-fabrication stage is also a good way to protect the solder mask. This way, the mask would be protected against oxidation and other contaminants prior to the boards’ assembly.
3. Store the Boards during the PCBA Stage
The moment you start the Printed Circuit Board Assembly (PCBA), endeavor to store it. This stage is when the PCB components or parts would be soldered to the boards.
The soldering process often leaves behind contaminants, such as flux residue. Leaving such behind often leads to impeded performances of the PCBs.
This is the reason why some PCB manufacturers have used different kinds of surface finishings to protect the copper traces.
4. Post-Assembly Storage is Recommended
The next step after assembling a PCB is to ship it to the clients or customers. Before then, final assembly measures, such as depanelization are in place. For this reason, ensuring the proper storage of the boards is required.
Besides, the boards will be transported either by road or air. Whether they are being shipped from you to the customers or from the Contract Manufacturer (CM) to you; the goal is to protect the boards.
To do that, do any of the following:
- Keep the boards in a PCB storage rack, which keeps them in position when in transport.
- Use encapsulation storage methods, such as conformal coating to keep the boards safe from unstable temperatures that often impact the components’ shelf life.
5. Keep the Boards during the Pre-Deployment Stage
Some Printed Circuit Boards (PCBs) are not used as soon as they are assembled and shipped. Some may take several months before they are put to use. That is a bit of a lengthy time and within this period, the boards could be damaged.
Hence, when the boards are stored over a long period of time, keeping them safe becomes a priority.
Following the recommended PCB storage guidelines will come in handy at this moment. The storage stage comes under any of the following:
- Post-assembly or after the board has been shipped and is then warehoused.
- Between the fabrication and Printed Circuit Board Assembly (PCBA) stage.
In case you don’t know what these guidelines are, we will talk about them in the next paragraphs.
The Best Printed Circuit Board Handling and Storage Guidelines
In this section, we introduce you to the PCB storage requirements to keep in mind, especially after the board has been assembled.
a. PCB Handling Measures
Let us start by talking about some of the best ways to handle and keep the PCBs safe.
b. Minimize Direct Handling
The first thought that comes to your mind is to use your hands to lift the PCBs. However, it is a bad idea. The rule is to avoid or minimize a direct contact and or handling of the PCB.
The best methods to minimize or reduce direct handling (hands-on contact) of the boards are:
- Transport the boards on ESD PCB storage racks.
- Place the boards in tray carts when transporting.
c. You Should Do the Direct Handling with Care
If there is a need to use hands-on contact or direct handling, then it must be done with care. For this purpose, wear clean gloves and hold the PCBs only by the edges. Never hold at the center or place your hands at the middle.
d. Avoid Statically-Electric Areas
If you are handling the PCBs, they must be kept away from the areas that tend to create static electricity. Examples of such areas or surfaces are:
- Rugs and;
- Carpets
e. Lotion Use is a No-No
You must not use products that compromise the boards’ quality. An example is hand lotion.
f. Prevent PCB Contamination when Transporting
Looking to transfer or transport the PCBs from one station to the other? You should do these:
- Keep all the stations clean, as that greatly helps in reducing the risks of Foreign Object Debris (FOD) contamination.
- Always use protective bags to package and transport the PCBs from one station to the other.
PCBA Storage Guidelines
We will now look at some of the industry-leading recommendations on how to safely store Printed Circuit Boards (PCBs).
a. Apply Surface Finishing
Do not miss out on applying surface finishing during the PCB fabrication process. This is important because the board might require a temporal storage after the fabrication, pending when it would be assembled.
The application of an appropriate finishing at this time helps to protect the board against contamination and oxidation.
b. Maintain a Controlled Environment
By a controlled environment, we mean that the PCB should be stored or kept where there aren’t excessive temperature changes. Understanding the PCB storage temperature and humidity is also a key to getting this right.
The ideal storage temperature and humidity recommendations are:
- 85% RH and;
- 86˚F or below ≤30˚C.
c. Be Selective with the Components
This is where you need to pay attention to the PCB components. The rule of thumb is never to use moisture-sensitive components.
Moisture-Sensitive vs. Non-Sensitive Components
These are components that are susceptible to moisture and are not. On the one hand, the moisture-sensitive components have a limited shelf life, which ranges from a day to one year, after the assembly. On the other hand, the non-moisture-sensitive components have a longer (and sometimes unlimited) storage lifetime, which could be up to 10 years after the assembly.
Getting it Right
Choosing Surface Mount Device (SMD) components that are not moisture-centric is one side of the coin. The other side is to store these parts in a controlled environment. An environment that matches these requirements is ideal:
- Relative Humidity (RH) of 85% and;
- A temperature of ≤30˚C or 86˚F.
d. Utilize the Older PCBs
Sometimes, circuit boards are no longer ideal for use due to the duration they have been stored. This is why it is recommended to ship out or use the older boards first before the newer ones.
This way, the older boards will be put to good use before their periods of shelf life is elapsed.
e. Store Circuit Boards in MBBs
Always use Moisture Barrier Bags (MBBs) to protect the PCBs. Here are some advantages of doing so:
- MBBs have either a plastic or metallic shield that keep the PCBs safe.
- These bags also protect the boards from contact with static electricity, especially, if you are using the boards around rugs or carpets.
- The ideal moisture-repelling feature of the MBBs is the use of film layers to control the absorption rate of moisture.
How to Maximize MBBs
Here is how to get the most out of storing PCBs in Moisture Barrier Bags (MBBs):
- Vacuum-seal and dry the Moisture Barrier Bags (MBBs), as that protects the bags from ESD.
- The best MBBs to use are the ones that have desiccant pouches, as these help to keep both humidity and moisture out of the bags. The desiccant also helps to absorb any moisture that enters or is trapped inside the MBBs.
Final Thoughts: Use the PCB Storage Solutions to Your Advantage
In addition to keeping to the PCB storage guidelines, it is also important to follow the IPC standard for PCB storage. You can refer to the IPC-1601 (Printed Board Handling and Storage Guidelines) and the IPC/JEDEC J-STD-033D (Handling, Packaging, Shipping and Use of Moisture, Reflow and Process Sensitive Devices) for an idea on what it takes to effectively protect a Printed Circuit Board (PCB) within and outside the production plant/factory.
