A Guide to PCB Conformal Coating Processes

Printed circuit board assemblies often operate in environments where moisture, dust, vibration, and chemical exposure threaten performance. In medical devices, aerospace, and defense systems, these risks are unacceptable.

This specialized coating provides a protective layer that extends product life, maintains electrical integrity, and supports reliable operation under harsh conditions. The process requires precise application and material selection tailored to the operating environment.

Our team integrates protective coating applications into high-reliability manufacturing workflows. Advanced equipment, skilled operators, and disciplined quality systems deliver assemblies that meet demanding performance and compliance requirements.

What is Conformal Coating?

Why is Conformal Coating Important in PCBA?

Reliability in a PCBA depends on its ability to resist moisture, dust, corrosive gases, and vibration. Even minimal contamination can lead to leakage currents, corrosion, or dielectric breakdown. The applied layer forms a barrier that helps prevent these failures, maintaining electrical and mechanical stability over time.



Sectors such as aerospace, defense, and medical technology often operate in extreme conditions. Coating helps protect mission-critical equipment, where a single fault could disrupt operations or compromise safety. For OEMs, the result is fewer field returns, extended product life, and stronger compliance with regulatory and industry standards.

Common Types of Coating

Selecting the Right Coating for Your Application

Coating selection begins with understanding the environmental conditions the assembly will face. Factors include temperature extremes, humidity, chemical exposure, and mechanical stress. Silicone is often chosen for high thermal cycling, while urethane performs well in chemically harsh conditions.

Electrical performance also plays a role. Dielectric strength, thermal conductivity, and coating thickness influence circuit behavior. Serviceability should be considered for products that may require rework.



At EI Microcircuits, coating selection is built into the design-for-manufacturability process. Our engineers collaborate with customers to match coating type, application method, and inspection standards to the assembly’s performance and compliance needs.

How to Apply Conformal Coating

Key Considerations

Surface preparation is essential. Any residue, flux, or particulates can reduce adhesion and shorten coating life. Cleaning processes must meet IPC requirements for ionic contamination.



Masking accuracy protects connectors, test points, and interfaces from unintended coverage. Controlled curing conditions help achieve the desired coating properties without damaging components.

For regulated industries, complete process traceability is required. This includes recording material batches, operator IDs, and inspection data as part of the assembly’s quality record.

Inspection & Quality Control

Challenges in Conformal Coating

Complex assemblies may have shadowed areas where coating is difficult to apply evenly. Sharp edges or irregular surfaces can cause pull-back or thin spots.



Material compatibility must be confirmed to avoid adverse reactions between coatings and component materials. Designs with many connectors or keep-out zones can increase masking labor.

Environmental factors such as temperature and humidity influence surface finish and curing quality. Addressing these challenges during product design improves reliability in the field.

EI Microcircuits’ Conformal Coating Capabilities 

EI Microcircuits’ capabilities include applying acrylic, silicone, urethane, and epoxy coatings in a controlled environment. Automated selective coating equipment increases accuracy and reduces labor.

All processes align with quality management systems such as ISO 13485 and AS9100D. Material tracking, inspection data, and operator records are linked to each assembly to maintain full traceability. This disciplined approach supports OEM programs in medical, aerospace, defense, and industrial markets.

Key Takeaways

PCB protective coating strengthens the reliability of PCB assemblies in demanding environments. Selecting the right material and applying it through a controlled process is key to long-term performance.

EI Microcircuits delivers coating solutions as part of a complete manufacturing workflow supported by advanced equipment and strict process control. This combination reduces risk, supports compliance, and meets the standards of high-reliability markets. Contact us today to discuss a solution for your next electronics assembly challenge.