Have you ever experienced the joy of trying to manually place a small component on an even smaller footprint pad layout or peering through a magnifying glass while reworking a 0201 resistor on a densely packed micro PCBA that somehow had become disconnected? If you have performed one of these or something equally challenging, then you surely realize the importance of taking proper handling precautions when working with circuit boards. And understand that failing to do so can lead to unintended damage and a useless board.
Manually handling PCBAs
Not only is handling important for components but for entire boards as well. And yes, failing to implement precautions when manually handling PCBAs can place your boards in a state of unusability. In some cases, you may be able to rescue your board from this fate. For example, if your board is subjected to condensation, baking is an effective PCB moisture protection method for removal. This is just one of the several measures you can take to prevent the premature demise of your boards. Let’s take a look at what PCB handling precautions you should know about and make use of for the manufacturing, production and storage of your boards.
PCB Handling Precautions for Development, Production and Storage
PCBA development is an iterative process for improving quality. The most desirable attributes of this process are speed, which provides time to achieve optimal quality, and flexibility, which allows for prototyping options such as parallel design. However, an optimal design can only be achieved if your boards are handled properly throughout the manufacturing, production and storage phases, as shown below.
Precautions for Development
- Avoid exposing copper traces to air
If your board’s copper traces are exposed to air, especially for protracted periods of time between fabrication and assembly, they may become contaminated from oxidation. The best way to avoid this is by applying an appropriate surface finish during fabrication.
- Avoid leftover debris
During PCB assembly (PCBA) debris may accumulate on your board. Due to its size, this may be hard to identify; therefore, employing optical inspection and cleaning your boards after assembly is always employed.
- Avoid excessive pressure and strain
When manually handling boards it is imperative not to apply excessive force or pressure as exceeding their structural integrity limitations may cause deformation or breakage.
- Wear protection
While manually handling boards it is also possible for contaminants to be deposited. This includes dirt, sweat, etc. Therefore, you should always wear gloves. It is also a good idea not to wear clothing where strings or other items may easily fall off and onto the board.
- Avoid condensation
If the temperature difference between your board surface and its immediate surroundings becomes great enough, condensation can occur that can lead to inaccuracy doing testing. This can be avoided by having an adequately ventilated testing environment and controlling the temperature.
- Use tools carefully
It is always important to exercise care when working on circuit boards; however, for small boards, the potential for doing damage is more acute, and using proper tools is critical.
Avoiding bad PCB handling is necessary when prototyping your design. Not doing so can cause delays in the development process; such as having to bake boards to remove moisture or the need for re-cleaning. Contaminated boards can also produce erratic behavior making it difficult to perform accurate testing.
Precautions for Production
Whether your design is intended for low-volume production or high-volume production, the primary objective is efficiency. That is achieving the best yield rate at the lowest per-unit cost. Although the target of production is narrower in terms of focus than development, the emphasis on PCB handling is not. In addition to applying all of the precautions listed above for manufacturing, considerations for transport: from your contract manufacturer (CM) and to your customer must be added for production, as listed below.
- Maintain a controlled environment
When shipping PCBAs the internal environment may need to be regulated. This is more of an issue for long transports or during inclement weather periods. It is recommended that the environment temperature is below ≤ 30°C (86°F) and 85% RH.
- Ensure boards are properly packaged
Proper packaging for PCBAs must be implemented. However, the requirements can vary depending upon factors such as; transport duration, environmental temperature and whether the boards have a conformal coating and/or are individually packaged.
Precautions for Storage
In many cases, your boards will likely be warehoused or stored prior to being installed. For this situation, the following precautions should be taken.
- Avoid moisture
One of the best ways to prevent moisture from reaching your boards is to store them in moisture barrier bags (MBBs) with desiccant. This is particularly important for long term storage.
- Avoid electrical static discharge (ESD)
Another potential problem is ESD, which can be prevented by using vacuum-sealed MBBs.
- Remove batteries for long term storage
Storing PCBAs for long periods of time with batteries installed can lead to a number of problems as these power supplies discharge or leak current over time. The best practice is to never install batteries before the installation of the board for operation, if possible.
Whether your boards are in manufacturing, production or storage, it is important that proper PCB handling precautions be taken. Failing to do so can result in delays or board failures.
|Tempo's Custom PCB Manufacturing Service
At Tempo Automation, proper board handling is incorporated throughout our manufacturing process. This includes cleaning every board assembled to remove any debris and avoid contamination that may negatively impact your boards’ quality.
And to help you get started on the best path, we furnish information for your DFM checks and enable you to easily view and download DRC files. If you’re an Altium Designer or Cadence Allegro user, you can simply add these files to your PCB design software. For Mentor Pads or other design packages, we furnish DRC information in other CAD formats and Excel.
If you are ready to have your design manufactured, try our quote tool to upload your CAD and BOM files. If you want more information on PCB handling precautions or how to incorporate them into your PCBA development or production, contact us.