Commonly used in consumer electronics, it provides good moisture and dielectric protection. It is popular because it is easy to apply, remove, and rework, and it dries quickly at room temperature. After the coating is applied, it typically forms a clear, smooth finish that simplifies inspection.
Ideal for applications requiring high reliability under extreme conditions, such as automotive electronics, aerospace, and industrial controls. It provides excellent thermal stability, flexibility, and superior moisture and dielectric protection. After the coating is applied, it forms a clear, smooth finish that simplifies inspection.
Ideal for applications requiring long-lasting performance in harsh environments, including industrial and military electronics. It provides strong resistance to chemicals, abrasion, and moisture. However, it is difficult to rework and can become brittle under strong vibration or temperature fluctuations.
Ideal for applications in harsh environments where maximum protection is required such as industrial, automotive, and heavy-duty machinery. It provides excellent chemical and mechanical resistance. However, it is difficult to rework and can become brittle under strong vibration or temperature fluctuations.
Ideal for aerospace, military, medical, and high-reliability industrial electronics. Because it is applied through vapor deposition it produces a thin and uniform layer of parylene coating on the entire PCB assembly, including complex geometries. It provides strong resistance to chemicals, moisture, temperature fluctuations. However, it is significantly more expensive than acrylic, silicone and urethane coatings and requires specialized vacuum chamber equipment.
Best suited for acrylic, silicone, urethane, and UV-curable coatings. It is the most used conformal coating method because it provides consistent, uniform coverage across the entire PCB assembly even when done manually. Automated spray systems are used for high-mix, large-volume production.
Best suited for acrylic, urethane, and silicone coatings. The coating is applied manually with a brush, making it suitable for small batches and touch-ups. While it’s low-cost and easy to apply, the method is labor-intensive, less consistent, and not ideal for high-volume production.
Best suited for acrylic, silicone, and urethane coatings. This method consists of submerging the entire PCB assembly into the coating solution, providing complete and uniform coverage. However, it requires extensive masking. It is typically used for high-volume production.
Best suited for acrylic, silicone, urethane, and UV-curable coatings. This method uses a specialized automated machine to precisely apply the coating to specific areas of the PCB assembly. While it requires a high initial investment, it greatly reduces or eliminates the need for masking. It is typically used for high-mix, high-precision production.
Used exclusively with parylene coating. This method involves using a vacuum process to deposit a thin and uniform layer of parylene coating on the PCB assembly.
Selective coating and vapor deposition are commonly used in aerospace, medical, and other high-reliability electronics applications.
The first step in the conformal coating process is to carefully clean and dry the PCB assemblies to ensure good coating adhesion and protection against contaminants and environmental stress. Remove all particles including oils and flux residues using a cleaning solution such as isopropyl alcohol. Make sure the boards are completely dry before coating to prevent adhesion issues.
Before applying the conformal coating use tape or caps to mask the areas in the PCB assemblies that should not be coated such as connectors, switches, LEDs, mounting holes, test points, or heat sinks.
After the assembled boards have been cleaned, dried and masked evenly apply a thin layer of conformal coating to protect the boards against contaminants and environmental stress. Use the application method recommended for the coating material and production volume.
After the coating is applied, cure it to form a strong and durable protective layer that holds firmly to the PCB assemblies. Insufficient curing may result in poor adhesion or reduced protection. Too much curing may cause brittleness or cracking.
After the conformal coating has been applied and cured, the PCB assemblies must be inspected under UV light and magnification to ensure that all surfaces requiring coating have received coverage, while masked areas remain free of coating.
After the conformal coating has been cured and inspected, carefully remove all masking materials and clean the boards before testing and final assembly.