Our team of manufacturing experts are quick to explain both the pros and cons of conformal coating. While the benefits of conformal coating may be well-known, the downsides are not as easily discerned. Let’s take a look at four reasons you may not want to conformal coat your boards.
As a refresher, conformal coating is the process of applying a thin layer of liquid, conforming material to a Printed Circuit Board Assembly (PCBA) to protect circuits and components from external and environmental factors.
What Are Some Conformal Coating Concerns?
- Lighting Requirements
- Environmental And Safety Regulations
To get the obvious out of the way, coatings are not applied free-of-charge. The cost of the material alone is prohibitive, as is the cost of labor to apply it. There are cheaper options, like acrylic based chemicals, but these options do not offer the most benefits to the end product. Depending on the surface area of the PCBA, the areas to be covered, and the application method, material cost can eliminate this as an option.
Coatings can be applied in an array of methods. Simple methods (like masking and spraying, brush application, or dipping if assembly allows) are preferred to help keep labor costs to a minimum. The more complex methods are those that utilize selective spray, selective flow, or vapor application. Depending on the production quantity, the usage, and required thickness, any number of these labor-intensive methods can be used, though these costs add to the raw assembly cost.
As stated above, conformal coatings are notoriously difficult to remove. While this bodes well in the field and for protecting your IP, this can make the rework of a defective board drastically more expensive or outright impossible – removal of the protective layer is only the first issue. After that, there’s the cleaning, the rework, a manual cleaning of the rework, then the re-application of the conformal. While there are solutions to this with acrylic-based coatings, acrylic may not be the most appropriate choice in the field.
This effect is massively exaggerated when discussing prototype, pre-production, or proof-of-concept builds. For this reason, it is highly recommended that programming, testing, and verification of the assembly’s functionality be done prior to the coating being applied. Finding out there is a defective component or a workmanship issue after the coating is applied can turn an otherwise great assembly into a nightmare.
If there are specific requirements to the LEDs on a PCBA, coatings can throw these specs out of tolerance. While there are coatings that allow for proper light transmission, specification, and identification, testing these products can be costly and time consuming. Masking methods can help prevent coating on these locations but are rarely perfect and may not be possible on surface mount LEDs without sacrificing the coverage of the components.
Not only can the regulations of the chemical on your assembly be a detriment to your licensing, but application of the product is subject to multiple environmental and employee safety regulations. Most application methods involve spray or vapor application, both of which are subject to heavy OSHA and environmental guidelines. Picking a safe coating is difficult, while designing a safe application process can be far more arduous. Depending on the regulations your product and your company are subject to, it may be easier to avoid it altogether.
With a wide range of coatings available on the market today, and new ones coming out every year, there is a large call to protect assemblies beyond great manufacturing. Protection from the environment, hazardous materials, and increased minimization all require the use of additional protection. Contact us to see how we can help protect your build!