Today’s electronics are deployed in increasingly demanding environments - in aircraft, medical devices, agtech applications and industrial infrastructure. In these unforgiving conditions, sensitive circuitry faces a barrage of threats. Moisture, dust, chemicals, extreme temperatures, and vibration can all take their toll, leading to system failures, costly replacements, and frustrated customers.
Conformal coating is a nearly invisible chemical layer that acts like armour for printed-circuit boards (PCBs), shielding them from environmental hazards that could impair their performance.
Conformal coating is widely used across a variety of sectors, from consumer electronics to performance-critical industrial settings. They ensure the long-term durability and compliance of circuit boards, helping to prevent failures that can cost money and even endanger lives.
While these coatings can be microns-thin, their application is a sophisticated science, demanding expert process controls and specialised equipment to get right.
So, whether you’re thinking about outsourcing or planning to manage your coating requirements in-house, understanding the highly controlled, multi-step conformal coating process is key to making the right manufacturing decisions.
Conformal coating machinery at work in ESCATEC's Malaysian plant
The first rule of conformal coating?
If the board isn’t clean, your coating won’t stay in place.
Contaminants like flux residues, oils, and dust particles can prevent the coating from bonding properly. This can lead to defects like delamination, pinholes and other issues. That’s why cleaning should be done using specialist solvents, followed by Dyne testing to confirm the correct surface energy.
Cleaning methods typically include:
Cleaning is aligned with IPC guidelines, including IPC-CH-65B, and should form a documented step in quality assurance protocols.
Skipping or rushing this phase can undermine everything that follows. Preparation should be treated as a critical quality control checkpoint—not just a formality.
Not all parts of a PCB should be coated.
Components like connectors, switches, sensor interfaces, and test points must remain exposed to ensure proper functionality. If coating is accidentally applied to these areas, it can cause electrical failures, poor signal contact, or mechanical issues - capillary action can draw coating fluid into unwanted zones.
To prevent this, precision masking is essential. This may be done manually using masking tape, latex, or custom silicone boots—some of which can be 3D-printed to fit specific components. Manual masking is flexible but time-consuming and prone to human error.
More advanced setups use digital masking, where “do-not-coat” zones can be programed into the machine. In this case, the system automatically avoids those areas, improving accuracy and reducing labour.
Where capillary action may occur a method of applying a gel barrier prior to the coating material can physically block coating intrusion. Together, these techniques ensure effective, targeted protection and support selective coating strategies crucial to maintaining PCB function.
Choosing the right coating material is about more than cost or ease of use.
Different materials offer different levels of protection based on environmental conditions, performance and compliance requirements:
Material selection should consider:
Conformal coatings are selected to balance these factors, guided by IPC-CC-830C and industry-specific durability standards.
Bear in mind medical device conformal coating may require different application standards compared to electronics present in other devices. For more information you can read our guide to medical device electronics ruggedisation.
Once the coating is selected, tight control over environmental and process variables is essential to ensure a consistent, defect-free result.
Critical variables for acrylic applications include:
Conformal coating machinery typically feature:
The goal is a uniform coating thickness across every batch - measured, documented, and validated to meet quality and compliance expectations.
Automation allows for high-volume, repeatable coating performance.
Boards can be mounted into bespoke or universal carriers and moved beneath robotic spray heads. Each PCB design requires a custom programme defining nozzle height, width, speed, and motion paths. Universal carriers offer flexibility for varied board sizes without the cost of custom tooling.
Because many coating compounds are flammable, particularly during application and drying, the process is typically enclosed and requires ATEX-rated extraction. This ensures compliance with health and safety standards and maintains a controlled application environment.
After application, the coating must be cured to achieve its protective properties.
Curing methods depend on the coating type:
Curing conditions are tightly managed to avoid issues like pooling, uneven thickness, or incomplete polymerisation.
Final inspection involves:
This inspection stage ensures every board meets defined acceptance criteria before integration into assemblies.
Setting up a conformal coating capability from scratch requires:
Outsourcing this process to a qualified electronics manufacturing partner enables access to all of this - without the capital expense, risk, or complexity of running it in-house.
It’s a cost-effective way to guarantee quality and protect your PCBs, while reducing the time and overhead of managing another specialised process internally.
Conformal coating isn’t just a protective measure—it’s a product quality guarantee. But getting it right takes more than just a spray gun and a clean room.
For OEMs building complete assemblies—from mechatronic sub-systems to sealed enclosures—outsourcing to a manufacturing partner who can integrate conformal coating into the broader PCB assembly and test process helps accelerate builds, reduce handling risks, and improve overall production efficiency.
If "built to last" is part of your brand promise, then partnering with an EMS provider equipped with advanced technology, trained coating technicians, and robust process control is how you ensure that promise is delivered.
Choose a partner who prioritises precision, compliance, and efficiency - at every layer.