Rules and guidelines are the foundation of any civilized society. With the proper guidelines in place, countries, states, kingdoms, and even families can function productively. Guidelines, in general, have an ultimate purpose, and it usually concerns order, safety, or care. Even a T-shirt has a set of instructions in place to ensure proper care when washing and drying it. A T-shirt of size XXL could exit the dryer as a size L if the appropriate washing and drying guidelines aren’t followed.
In terms of PCB care, guidelines are in place to ensure proper storage and handling to minimize the likelihood of failure. Overall, a printed circuit board requires gentle handling and optimal storage conditions. This, in turn, promotes higher PCB quality, expands product lifecycle, and maximizes proper functionality as well as performance. We will examine potential reasons for PCB failure before discussing important rules for handling and storing your PCBs based on the IPC 1601a printed board handling and storage guidelines.
10 Common Reasons for PCB Failure
There seems to be a misconception that components and devices fail only due to poor craftsmanship, wear and tear, or faulty components used in their fabrication. Although these are among the myriad of causes of electronic device failure, they are still only a portion of all the possible reasons for device failure. The following is a list of ten common reasons for electronic device failure:
- Poor surge arresters: This is a common reason for electrical equipment failure due to voltage spikes and surge arrester failure.
Note: A surge arrester is a device to protect electrical equipment from over-voltage transients caused by external (i.e., lightning) or internal (i.e., voltage surge) events. Furthermore, they are also called transient voltage surge suppressors or surge protection devices. Moreover, they are predominantly in use in power transmission and distribution systems as protective devices.
- Lightning: A natural occurrence.
- Grounding issues: Inadequate grounding or ground failure.
- Capacitive coupling: The transfer of energy between distant networks or within an electrical system, through displacement current between circuit nodes, and caused by the electrical field.
- Inrush current: The instantaneous maximum input current produced by an electrical device when powered on.
- Unbalanced sags: A voltage sag is a short-term reduction in RMS voltage.
Furthermore, this can be the result of an overload, starting of an electrical device (motor), or even a short circuit. Finally, voltage sag is when the RMS voltage decreases between 10% and 90% of the nominal voltage level for one-half cycle to a minute.)
- Equipment wear and tear: Standard device use.
- Contact with higher voltage lines
- Improper handling
- Not following appropriate storage guidelines
Improper handling and storage are two of the most overlooked causes of electronic device failure, and following IPC 1601a guidelines can help mitigate potential problems.
IPC 1601a Printed Board Handling and Storage Guidelines
Before the implementation of the current standards in use today, the PCB industry as a whole relied on military standards. However, storage and handling guidelines used by the military did not correctly define methods for packaging PCBs to preserve their quality and reliability during shipment or storage. In addition, many of the military’s guidelines in use are obsolete and do not address PCB-free assembly processes or the newer laminates and final finishes.
Therefore, in 2010, the IPC issued IPC-1601a: Printed Board Handling, and Storage Guidelines. These guidelines provide advice on protecting PCBs from physical damage, solderability degradation, contamination, moisture uptake, and electrostatic discharge (ESD).
In most cases, a PCB manufacturer can and will go above and beyond to ensure a high-quality product. This is where many people believe that the need for extreme care and concern ends. This could not be further from the truth, however. Although the proverbial torch is passed to the client once they receive the product, it does not mean that the necessary guidelines, as presented in the next section should be relaxed.
Necessary Precautions for Handling Printed Circuit Boards
Maintaining the viability of PCBs is an ongoing process that requires rigorous adherence to standards. Necessary precautions, as outlined by IPC 1601a, must be taken to ensure the proper handling and storage of PCBs, thereby elongating PCB lifetime and minimizing the likelihood of dysfunction or failure.
Limit physical handling
As a general rule, you should limit the physical handling of your PCBs and utilize a dedicated tray cart or transport rack whenever possible. When physical handling cannot be avoided, make sure the handler wears clean gloves throughout the process, even if the PCB is contained within its packaging.
Handle PCB by its edges, touch lightly, and minimize pressure
Furthermore, when handling a PCB, be sure to pick it up and hold it by its edges. If you have ever handled a DVD, Blu-ray, or CD, you may understand the general precautions that need to be followed here as well. These precautions include using light touches and exerting as little pressure as possible to protect the PCB while maintaining a secure grip to avoid drops.
Minimize time outside protective casing
Other PCB handling guidelines include placing it inside of a protective bag when it’s not being used. The more time the PCB spends outside of its protective casing, the higher the possibility of exposure to moisture. Keep in mind that the chance of moisture exposure increases in a humid environment, so additional precautions may need to be taken in those cases.
Ensure adequate packaging to protect from liquid
Moisture is one of the major causes of catastrophic failure in PCBs and electronic devices alike. Since PCBs are extremely moisture sensitive, circuit boards destined for prolonged exposure to a moisture-rich environment will require baking. Make sure your PCBs arrive vacuum-sealed and include a moisture level indicator, which provides the floor life of your PCB before it needs baking.
Cleanliness is a top priority for all areas when handling any PCB. This includes clean workstations, clean hands, and clean gloves, as well as eliminating sources of contamination.
Take steps to avoid static electricity buildup
Also, be sure to keep liquids and any possible sources of static electricity away from your PCBs. Finally, make sure that these guidelines are not only understood but adhered to by all personnel involved in the fabrication process.
While these guidelines may seem excessive or even overwhelming at first, they are necessary as well as critically important. Regardless of the type or specification, all PCBs are sensitive, thus requiring both care and attention. Even the most rugged design can lose both functionality and viability without proper handling. But while proper handling is part of the solution, proper storage is equally important in maximizing the lifetime and overall functionality of your PCBs.
Necessary Precautions for Storing Printed Circuit Boards
In a game of football, you can witness a perfect sack escape followed by a perfect throw, but if the wide receiver drops the pass, well... you get the idea. This analogy epitomizes the scenario of following all of the guidelines for handling your PCB but failing to store your PCB correctly.
Although there are various types and designs for PCBs and not all PCBs utilize the same storage solutions. There are some universal precautions for storage that should always be taken.
As previously stated, moisture is a critical concern that promotes various other potential problems. For example, if a PCB absorbs moisture, soldering can cause partial separation of the PCB’s layers or delamination due to the expanding of the moisture. This, in turn, can result in PCB failure while in the field or during testing. Furthermore, moisture promotes diffusion or oxidation, thereby causing component corrosion or actual (board) cracking.
Be wary of temperature variations and extremes
You may remember two temperature extremes from one of your earliest science classes: 320 F and 2120 F. These are, of course, the freezing and boiling points of water, respectively. Temperature changes can greatly affect PCBs (via expansion and contraction), and the effects intensify if the PCB absorbs even a minute quantity of water. Expansion and contraction can both compromise PCB viability and functionality, not to mention the effects that temperature changes can have on the board in general.
Consider electrostatic discharge (ESD)
ESD promotes component degradation as well as component failure. To minimize the likelihood of these issues, create an anti-static storage environment and follow proper grounding procedures.
Just like with PCB handling, maximizing cleanliness is a crucial part of proper PCB storage. Cleanliness is especially important for PCBs designed for sensitive medical device applications.
Contamination, corrosion, shorts, and warping are only a few of the myriad potential issues that could arise from improper storage of PCBs. However, the elimination of these hazards is possible through the utilization of a dedicated PCB storage space that minimizes moisture and maintains a steady temperature. It is recommended that boards be stored at < 40 °C and 90% RH if storage is to be at least 12 months. A general rule of thumb is: a drier storage area equals increased protection for your PCBs.
In general, when storing your PCBs for extended periods of time, consider creating dry shield bags or dry packages. These particular packages consist of:
- Moisture-sensitive label
- Desiccant packs
- Moisture barrier bag
- Humidity indicator card
In conclusion, the guidelines set by IPC 1601a are in place to protect PCBs by managing a variety of possible risks. However, keep in mind that the exact specifications of proper handling and storage may depend on the type as well as requirements of your specific PCB. Consult your contract manufacturer (CM) to ensure adherence to IPC 1601a guidelines.
Work with a CM to Maximize PCB Functionality and Longevity
Regardless of the specific methods used, ensure that the measures you take (for handling and storage) adhere to IPC standards while effectively addressing the issues and common hazards that can compromise PCB integrity. At Tempo, the industry’s fastest PCB prototype and low volume manufacturer, we have the capabilities to ensure that your design intent is met and your boards are buildable.
|Tempo's Custom PCB Manufacturing Service
We will work with you throughout the PCB development process and advise you on the best PCB handling and storage guidelines to maximize the functionality and longevity of your PCBs.
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 implementing the IPC 1601a guidelines for PCB handling and storage, contact us.