How Does Conformal Coating Impact a Printed Circuit Board?

Conformal Coating Impact a Printed Circuit Board

Conformal coating enhances the functionality of a printed circuit board by protecting it from operating environments, reducing failure rates and increasing its working life. There are several types of conformal coating, and selecting the best material for a specific application requires balancing the protective properties of the coating against the practicalities of application and removal.

A key consideration is the PCB’s worst-case operating temperature, as this may limit which conformal coating materials are suitable for use or require rethinking of thermal management strategies to reduce temperatures to acceptable levels. Coating thickness requirements are also important; too thin a coating can create mechanical stress points due to differential movement, while too thick a coating can crack or become brittle, and offer less protection than a thinner one.

Other factors include the choice of coating application method, which can vary depending on the production speed and prep work required as well as the component types and placement on the board. Dips are generally used in mass production, while brushes and spraying offer more flexibility for small-scale production or touch up applications. Humidity testing is often performed to ensure the conformal coating will resist moisture, which can lead to corrosion of metal components and connections on a smt pcb board.

Once the board has been coated, it is cured as per the manufacturer’s instructions, typically by running the board through an oven for a specified duration. It is then inspected for defects, such as bubbles or pinholes in the coating. Once the defects are repaired, the board is ready for use.

How Does Conformal Coating Impact a Printed Circuit Board?

Conformal coating can be applied using dipping, spraying, brushing or vapor deposition techniques. The choice will depend on the size of the board, the type of components and their placement on it, the production volume and budget.

It is essential that the board is thoroughly cleaned before the application of the conformal coating, to avoid compromising the integrity of the coating. This cleaning process can be conducted with a solvent-based cleaner such as isopropyl alcohol, and should be performed before all manufacturing steps to ensure that any contaminants do not interfere with the adhesion of the conformal coating.

The PCB should be tested for suitability to operate in the final environment it will be used in, including ion chromatography and humidity tests as described above. Conformal coating can be used to protect a smt pcb board in a wide range of operating conditions, and is an alternative to more expensive and complicated encapsulation processes. This is particularly important for boards that control automobile engines or other high-speed machinery, which can experience extreme heat and vibration abuse.

For this reason, a conformal coating is widely used in industrial electronics, and it can be found in many consumer products. Ideally, the conformal coating should be specified during the electronic design stage of the board, and this specification can be exported to a production partner using tools such as Altium Designer. This will help to streamline the manufacturing process, as the smt pcb will already be designed to take advantage of the protective properties of the conformal coating that is chosen.

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