Conformal Coating for PCBs: Types, Applications, and Selection Guide
How to choose the right conformal coating to protect your PCB from moisture, dust, chemicals, and temperature extremes
Why Conformal Coating Matters
Conformal coating is a thin protective film applied to PCBs after assembly. It protects against moisture, dust, chemicals, fungal growth, and temperature extremes. For electronics deployed in harsh environments — outdoor equipment, automotive under-hood applications, industrial machinery, and marine electronics — conformal coating can be the difference between reliable operation and premature failure.
The coating "conforms" to the contours of the PCB, covering components, solder joints, and exposed copper while leaving connectors and test points accessible (when masked appropriately).
Types of Conformal Coatings
| Acrylic (AR) | Silicone (SR) | Urethane (UR) | |
|---|---|---|---|
| Temperature range | -40°C to +125°C | -65°C to +200°C | -40°C to +125°C |
| Moisture resistance | Good | Excellent | Good |
| Chemical resistance | Moderate | Good | Superior |
| Flexibility | Moderate | Excellent | Moderate |
| Rework difficulty | Easy — solvent removal | Difficult — mechanical removal | Very difficult — requires abrasion |
| Best for | General-purpose, indoor industrial | Automotive, high-temperature | Harsh chemical environments |
Each type has specific application methods — spraying, brushing, or dipping — and different curing requirements (air dry, heat cure, or UV cure).
Selecting the Right Coating for Your Application
The choice of conformal coating depends on the operating environment. Indoor consumer electronics rarely need coating. Industrial equipment in humid environments benefits from acrylic. Automotive electronics exposed to temperature extremes and fluids need silicone or urethane.
Superb Automation offers all three coating types with masking, application, inspection, and cure capabilities. Our team can recommend the best coating for your specific application environment.
