How Long Do Circuit Boards Last ?
PCBs are fairly stable components. Yet, they are produced in bulk, and it may take months for a supplier to sell them and manufacturers to place them in their electronics.
There are some concerns regarding the life expectancy of control boards. Known cases of PCBs that are 25 years old are not unheard of. Potentially, such components may withstand 100 to 120 years of shelf life under ideal conditions.
In this post, Let’s learn what impacts their life span.
Factors that Affect the PCB lifespan
Let’s distinguish the risk factors into two different categories: ones that affect PCB life expectancy before and during storage.
Pre-Storage Threats:
Here are some of the most common risks to which components are exposed to even before their shelf-life begins.
- Soldering
The primary concern is the creation of a good solder joint between the electronic components and the bare laminate. Soldering issues cause intermittent connectivity problems. These basically result in the poor quality of circuit boards and, respectively, low life expectancy.
- Protective and conformal coating
Typically, PCB manufacturer always apply protective coatings or conformal coatings to prevent solder bridges and other issues. Protective coating of PCB finish is ENIG, immersion gold/silver, or any other.
Surface finishes are already the determinators of shelf life for all types of PCBs. For one, a lead-based finish lasts for 2 years, approximately. Lead-free finishes, such as immersion silver or organic solderability preservatives, last for 6 months or less.
As for conformal coating, it’s the application of film or any other protective material after the board jas already been assembled. It protects circuit boards from salt cells spray, moisture, dust, mold, corrosion, and more.
- Assembly process
Another important consideration is the assembly process itself. It typically involves adhesives, solder epoxy, and some chemicals. Toxic compounds negatively affect the shelf life expectancy of any PCB.
Even the working environment in which fabrication was performed impacts the life expectancy. Relative humidity, temperature, vibrations, dust, metal chips, solder drops, and more affect the end outcomes of assembling.
- Quality Assurance (QA)
Not every manufacturer of PCBs pays decent attention to QA practices. Not to mention quality testing in the fabrication process, there are some other quality-related aspects.
First in and first out (FIFO) inventory control. This nuance is what ensures that a random PCB does not get an outdated component. Another matter of concern is component labeling for tracking. Proper labeling ensures that a transportation company handles and stores components as per requirements.
Besides, the use of materials, such as adhesives or epoxy, also matters. If these are still in use even after their expiration date, the end quality and, respectively, life expectancy or components may deteriorate significantly.
Finally, the bare storing of raw materials, such as solder paste, is equally important. Monitored and alarmed refrigeration for cold product storage is what prevents manufacturers from applying inadequate quality finishes, for example.
- Design choices
Not every PCB manufacturer pays decent attention to QA practices. Not to mention quality testing in the fabrication process, there are some other quality-related aspects.
First in and first out (FIFO) inventory control. This nuance is what ensures that a random PCB does not get an outdated component. Another matter of concern is component labeling for tracking. Proper labeling ensures that a transportation company handles and stores components as per requirements.
Besides, the use of materials, such as adhesives or epoxy, also matters. If these are still in use even after their expiration date, the end quality and, respectively, life expectancy or components may deteriorate significantly.
Finally, the bare storing of raw materials, such as solder paste, is equally important. Monitored and alarmed refrigeration for cold product storage is what prevents manufacturers from applying inadequate quality finishes, for example.
You may see that MSD 1 is the least durable component. Given the storing conditions of less than 30 degrees Celsius and 85% of relative humidity, they not gonna deteriorate for a prolonged time. It means that if a PCB has such components only, it will likely have an extended shelf life.
The opposite is also correct since MSD 6 will ensure a shortened shelf life even under ideal conditions.
- Shipping conditions
In some cases, manufacturers have to transport PCBs to a warehouse to store them properly. Unfortunately, during this procedure, some threats may additionally affect a PCB, shortening its life span this way.
In the best-case scenario, PCBs are shipped in a temperature-controlled vehicle. This helps to prevent substantial temperature and relative humidity fluctuations. The latter results in internal moisture in layers of PCBs, which is of no good.
Physical stresses and simple vibrations over time also may impact the state of PCBs being transported. Careful shipping is what helps not to deteriorate shelf life.
Shelf-Life Threats:
Finally, here are the treats to the life expectancy of components being stored.
- Handling
Expect but transportation, there are other instances in which workers handle PCBs. For example, that moving them from one production stage to another. Some PCBs, especially ones with immersion silver or immersion gold finishes, are extremely prone to inadequate handling.
The result of not careful handling is typical scratches that expose parts of PCBs. copper under these scratches oxidizes over time resulting in poor board functioning and signal loss.
- Storing Conditions
Finally, the aspect of extreme importance — relative humidity, temperature, sun exposure, physical stresses, etc. There are nuances in storing components in warehouses.
If boards were contaminated before their shelf life began, the formation of oxidation would take somewhere between two and 10 years. Yet, the better storing is, the less are risks that a perfect board would deteriorate for any reason. Basically, storing intact boards is what may ensure a shelf life of 100 years or more.
Different PCBs have distinct storing requirements, but 20-30 degrees Celsius and less than 75% relative humidity are perfect. You also should protect PCBs from UV light and sunlight since both may make soldering soften.
It’s also recommended not to stack boxes of PCBs onto each other. This helps to prevent boards on the bottom from experiencing unnecessary stresses.
Final Word
Regardless of the types of PCBs, they all have an expected shelf life. It’s rare when manufacturers guarantee more than a year of storage without compromising the quality of boards.
Yet, as you already know, cases of PCBs living through decades are absolutely not unheard of. If you ensure ideal assembly, careful handling, and proper environmental conditions, maybe your archive examples of PCBs will last for more than a hundred years.
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