Introduction
Power electronics are increasingly required to operate in demanding environments while maintaining high reliability, efficiency, and serviceability. Applications ranging from industrial motor drives and power supplies to automotive modules and renewable energy systems expose electronic assemblies to moisture, dust, chemicals, vibration, and temperature variation. Conformal coatings are widely used to protect printed circuit boards (PCBs) from these environmental stresses, extending product life and reducing field failures.
Among the various conformal coating chemistries available—including acrylics, polyurethanes, silicones, and epoxies—acrylic-based conformal coatings remain one of the most commonly selected options for power electronics. Their balance of performance, processability, and reworkability makes them particularly attractive in applications where protection is required without sacrificing manufacturability or service access.
This article explores the key advantages of acrylic conformal coatings and explains why they are often well suited to power electronics designs.
Overview of Acrylic Conformal Coatings
Acrylic conformal coatings are typically solvent-based polymer systems that form a thin, transparent protective layer over electronic assemblies. Once cured, they provide a continuous barrier that conforms closely to the surface geometry of components, solder joints, and tracks.
They are usually applied via spraying, dipping, or selective coating processes and cure primarily through solvent evaporation, rather than chemical crosslinking. This relatively simple curing mechanism underpins many of their practical advantages.
Environmental Protection Performance
Moisture and Humidity Resistance
One of the primary reasons for applying conformal coating in power electronics is protection against moisture and humidity. Acrylic coatings provide excellent resistance to condensation and high-humidity environments, significantly reducing the risk of corrosion, dendritic growth, and leakage currents.
For power electronics operating at elevated voltages, moisture-induced leakage paths can cause efficiency losses, control instability, or catastrophic failure. Acrylic coatings form an effective moisture barrier that helps maintain insulation resistance across high-impedance nodes and between power conductors.
Dust and Contamination Protection
In industrial and outdoor environments, airborne dust, conductive particles, and chemical contaminants pose a serious reliability risk. Acrylic coatings seal exposed copper, solder joints, and component leads, preventing contamination from settling directly on electrically sensitive areas.
This is particularly valuable in power electronics, where switching nodes and gate-drive circuits can be highly sensitive to contamination-related leakage or noise coupling.
Electrical Performance Benefits
Good Dielectric Properties
Acrylic conformal coatings exhibit strong dielectric strength and insulation resistance, making them suitable for use around high-voltage and fast-switching circuits. While they are not a substitute for proper creepage and clearance design, they provide an additional layer of electrical insulation that enhances robustness.
In power electronics designs where PCB density is increasing, this additional insulation margin can help reduce the risk of arcing, partial discharge, or surface tracking—especially in humid conditions.
Minimal Impact on Circuit Performance
Compared to some thicker or more rigid coating systems, acrylic coatings are relatively thin and lightweight. This minimises their impact on parasitic capacitance and thermal behaviour, both of which are critical considerations in high-frequency power electronics.
Their stable electrical properties across a wide operating temperature range further support predictable system performance.
Thermal Characteristics
Compatibility with Heat-Generating Assemblies
Power electronics inevitably generate heat, and any protective coating must coexist with thermal management strategies rather than compromise them. Acrylic conformal coatings have moderate thermal conductivity and, when applied correctly, do not significantly impede heat transfer from components such as MOSFETs, gate drivers, or power resistors.
While they are not intended to function as thermal interface materials, acrylic coatings are thin enough that they generally do not introduce problematic thermal resistance when used appropriately.
Stable Performance Across Typical Operating Temperatures
Acrylic coatings typically perform well across the temperature ranges encountered in many industrial and commercial power electronics applications. They maintain flexibility and adhesion under thermal cycling, reducing the risk of cracking or delamination that could expose vulnerable areas of the PCB.
Ease of Application and Manufacturing Advantages
Simple Processing and Fast Drying
One of the strongest advantages of acrylic conformal coatings is their ease of application. They can be applied using standard spray equipment, dip tanks, or automated selective coating systems, making them suitable for both low-volume and high-volume production.
Curing occurs primarily through solvent evaporation, which allows for relatively fast drying times compared to coatings that require heat or moisture curing. This supports efficient production flow and reduces energy consumption during manufacturing.
Visual Inspection and Quality Control
Most acrylic coatings are naturally transparent and have good optical clarity. This makes post-coating inspection significantly easier, allowing solder joints, component markings, and test points to remain visible.
In power electronics manufacturing, this visibility simplifies quality control, fault investigation, and audit processes, particularly when compared with opaque or heavily pigmented coatings.
Reworkability and Serviceability
Ease of Removal for Repair or Modification
A key differentiator of acrylic conformal coatings is their excellent reworkability. Acrylic coatings can typically be removed using dedicated solvents or localised mechanical methods without damaging the PCB or components.
This is a major advantage in power electronics, where repair, modification, or post-production changes may be required. In contrast, coatings such as epoxies or some polyurethanes can be extremely difficult—or impossible—to remove without causing damage.
Support for Prototyping and Iteration
During development and early production phases, designs often evolve. Acrylic coatings allow manufacturers to protect assemblies without locking themselves into an irreversible process. This flexibility is particularly valuable in power electronics projects where firmware changes, component substitutions, or layout refinements are common.
Cost Effectiveness
Lower Material and Processing Costs
Acrylic conformal coatings are generally among the most cost-effective options available. Their raw material costs are typically lower than silicones or specialised urethane systems, and their simple curing requirements reduce processing overhead.
For power electronics manufacturers operating at scale, these cost advantages can be significant, especially when combined with reduced scrap rates and faster production throughput.
Balanced Performance-to-Cost Ratio
While acrylic coatings may not offer the extreme chemical resistance of epoxies or the high-temperature performance of silicones, they provide a well-balanced level of protection for a wide range of power electronics applications. This makes them an attractive “default” choice where no extreme environmental requirement dominates the design.
Limitations and Appropriate Use
It is important to acknowledge that acrylic coatings are not universally optimal. They are generally less resistant to aggressive solvents, fuels, and prolonged chemical exposure than some alternative chemistries. Similarly, for very high-temperature or under-hood automotive environments, silicone coatings may be more appropriate.
However, for many industrial, commercial, and controlled-environment power electronics applications, acrylic coatings offer an excellent balance of protection, practicality, and cost.
Conclusion
Acrylic-based conformal coatings continue to play a vital role in the protection of power electronics. Their strong moisture resistance, good dielectric properties, ease of application, and exceptional reworkability make them particularly well suited to designs where reliability and manufacturability must coexist.
For power electronics manufacturers seeking a practical, cost-effective coating solution that supports both production efficiency and long-term serviceability, acrylic conformal coatings represent a proven and versatile choice. When applied as part of a well-engineered protection strategy, they contribute significantly to product robustness and lifecycle value.