What is Conformal Coating?
Conformal coating is a protective layer applied to the PCB assemblies of power supplies to improve durability and performance in industrial environments. It helps shield sensitive components from moisture, dust, and other airborne contaminants. But there's still confusion about what it actually accomplishes, and what expectations are unrealistic.
This article focuses on acrylic coatings, the most common choice in industrial-grade conformal coated power supplies, medical grade conformal coated power supplies, and DIN rail conformal coated power supplies. While most manufacturers do not publish an exact thickness specification, it's generally understood they follow industry norms.
What Conformal Coated Power Supplies Actually Protects Against
- Humidity and moisture: acrylic helps limit corrosion and leakage currents caused by damp air or occasional condensation.
- Dust and particles: prevents buildup on conductive surfaces, reducing the chance of shorts and arcing. It also reduces the likelihood of current paths forming between conductors in high voltage or polluted environments.
- Chemical vapors and contaminants: offers some defense against corrosive gasses that might otherwise degrade board materials.
- Thermal cycling: acts as a buffer during minor expansion and contraction of components due to changing temperatures.
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Why Is Acrylic Used for Conformal Coating?
Acrylic is widely used because it strikes a practical balance between protection, ease of application, inspection, and serviceability. It dries quickly, adheres well, and is cost effective.
According to IPC-A-610 standards, the recommended coating thickness for acrylic ranges from 30 to 130 micrometers. Specialty Coating Systems (SCS) suggests that 50 to 75 µm is the sweet spot for most industrial applications.
Common Misconceptions: What Conformal Coated Power Supplies Don't Achieve
- Overheating problems: conformal coating does not dissipate heat. It may reduce thermal stress during rapid temperature changes, but it will not fix undersized heatsinks or poor ventilation.
- Waterproofing solution: coated supplies are more resistant to condensation and splashes, not submersion. You still need proper IP rated enclosures for wet environments.
- Mechanical protection: the coating will not protect against vibration, shock, or physical impact. That is still a job for the enclosure and mounting system.
Frequently Asked Questions
What is the standard thickness for acrylic conformal coating on power supplies?
According to IPC-A-610 guidelines, the standard thickness for acrylic conformal coating ranges from 30 to 130 micrometers (µm). For most industrial power supplies, manufacturers target a sweet spot of 50 to 75 µm to ensure robust environmental protection without trapping component heat.
What is the difference between acrylic and silicone conformal coatings?
Acrylic coatings are cost effective, dry rapidly, and are easy to rework or repair using standard solvents. Silicone coatings are preferred for extreme temperature environments, often exceeding 150°C, and high humidity applications, but they are much more difficult to remove during repairs.
Does a conformal coated power supply make it waterproof?
No, conformal coating does not make a power supply waterproof. While it provides excellent protection against humidity, condensation, and accidental splashes, it cannot withstand submersion. Applications requiring true waterproofing still need an appropriately IP rated (Ingress Protection rated) enclosure.
Can conformal coating allow for tighter component spacing on a PCB?
Yes, conformal coating can reduce spacing requirements on a printed circuit board (PCB). It provides high dielectric strength, which helps prevent arcing and corona discharge. Under safety standards like IPC-2221, applying a coating allows for reduced clearance and creepage distances between high voltage traces during the design phase.
Final Thoughts on Conformal Coating
Acrylic conformal coated power supplies are an effective and proven way to improve the environmental resilience of a power supply. It's a standard feature in many Delta DRF models and other conformal coated power supplies. But it's not a magic fix. It complements, but does not replace, good system design, thermal management, and mechanical protection.
If you're deploying DIN rail power supplies in demanding applications, confirm whether conformal coating is present, what type is used, and how it fits into your broader reliability strategy.
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Contact the engineering experts at TRC Electronics today. Give us a call at 1-888-612-9514, and let us support you with the perfect Conformal Coated Power Supply solution for your operational needs.
References
- IPC-A-610: Acceptability of Electronic Assemblies. IPC Association. ipc.org
- IPC-CC-830: Qualification and Performance of Electrical Insulating Compound for Printed Board Assemblies. IPC Association. ipc.org
- IPC-2221: Generic Standard on Printed Board Design. IPC Association. ipc.org
- Techspray: The Essential Guide to Conformal Coating. Techspray Technical Resources. techspray.com
Last Updated: September 13, 2026