Function of Conformal Coating in PCBs
Printed circuit boards (PCBs) have a multitude of functions that allow them to perform vital electronic duties. They also need to be protected from environmental conditions, including moisture, abrasive particulates and chemicals, and extreme temperatures. This is where conformal coating comes in, which provides a layer of protective material that prevents these conditions from damaging the board and its components.
Conformal coatings can be applied in a variety of ways, depending on the manufacturer and its capabilities. One popular method is dipping, which involves submerging a PCB in an acrylic or epoxy coating. While this offers good corrosion resistance, it can be a labor-intensive and costly process. Another option is spraying, which can be used with automated or robotic systems that allow for programmable spray nozzles that limit application to specific areas of the board. This allows for high-volume production and can be an ideal solution when masking areas is necessary to protect sensitive components and circuitry.
In addition to the chemical and corrosion protection offered by conformal coatings, they can also offer electrical insulation and thermal management properties. These can help improve the performance of a circuit board, as well as extend its working life. However, it’s important to note that not all conformal coating materials are created equal and their use will impact how a pcb operates.
What Is the Function of Conformal Coating in PCBs?
For example, some coatings are highly insulating and can trap heat, which may cause hot spots and potentially reduce the efficiency of the system as a whole. Conversely, some coatings are thermally conductive and can disperse heat more effectively, which can increase the speed at which a circuit board can reach operating temperature.
It’s also essential to keep in mind that conformal coatings will have a direct impact on how easy it is for technicians to access and repair a circuit board. Some coatings are harder to remove than others, which can add time and complexity to rework and repairs. Conformal coatings also have a direct impact on how the surface of a circuit board appears, which can have a noticeable effect on its aesthetics and branding.
To ensure the best possible results, PCB manufacturers should choose a conformal coating that is certified to meet industry standards for worker safety and environmental protection. Additionally, it’s important to consider the manufacturing processes that will be used to apply the conformal coating. For example, vapor degreasing and aqueous washing are critical before coating to ensure that all contaminants have been removed. This will ensure that the conformal coating does not have any pinholes, which could make contact with sensitive components and form undesired conductive paths.
The final consideration for selecting the proper conformal coating for a PCB is its intended operating environment. This can be determined by reviewing the relevant specifications and assessing the requirements of the product to determine whether it will require conformal coating or not. In many cases, a PCB performing mission-critical services will be required to be conformally coated to ensure its durability and long-term performance. For this reason, PCB designers should incorporate the specification of conformal coating into their design using tools like Altium Designer.