Short answer: A PCB needs conformal coating when it will see condensation, salt or corrosive air, dust, chemical splashes or washdown, or vibration with fine-pitch components. That covers most marine, outdoor, agricultural, energy and industrial-automation electronics. A board in a dry, sealed indoor cabinet usually does not need it. Coating typically adds €0.50–€3 per board in series with automated selective coating, and around 1–2 days to the process.
What conformal coating does
A thin (25–75 µm) polymer film over the assembled board that blocks moisture, ionic contamination and dust from reaching the copper and solder joints. It does not seal the board like potting; it makes the surface survive a humid, dirty or vibrating life. Selected areas such as connectors, test points and heat sinks are masked or left uncoated.
Environments that require coating
| Environment | Coating | Typical material |
|---|---|---|
| Marine, coastal, offshore (salt, condensation) | Required | Urethane (AR/UR) or silicone |
| Outdoor, unheated cabinets, agriculture | Required | Acrylic or urethane |
| Industrial washdown, chemicals, oil mist | Required | Urethane or silicone |
| High vibration with 0.4 mm pitch or smaller parts | Recommended | Acrylic (thin, easy rework) |
| Dry indoor enclosure, IP54 or better, controlled temperature | Usually not needed | — |
| Medical devices with cleaning agents | Case by case | Per IEC 60601 risk analysis |
Which coating material?
- Acrylic (AR): easiest to apply and rework, good moisture protection, limited chemical resistance. The default for industrial and IoT boards.
- Urethane (UR): best chemical and abrasion resistance, harder to rework. Marine and washdown.
- Silicone (SR): widest temperature range, flexible, good for thermal cycling and high vibration.
- UV-curable: acrylic or urethane chemistry that cures in seconds under UV, enabling in-line, fully automated coating with consistent thickness.
How automated coating changes the economics
Comtec Labs applies coating with an automated selective coating machine and UV cure. The programme defines exactly which areas are coated and which are kept clear, the thickness is repeatable board to board and the cure takes seconds instead of hours. That is why coating in series costs a fraction of a manual spray-and-mask process and why we can offer it as a standard step on the production line.
Key facts
- Coating adds typically €0.50–€3 per board in automated series production.
- Thickness per IPC-CC-830 / IPC-A-610: 25–75 µm for acrylic, urethane and silicone.
- Selective coating masks connectors and test points automatically; no manual taping.
- Coating is inspected under UV light: most materials include a UV tracer for 100 % visual check.
Design notes before you coat
Keep connectors, test points and adjustable parts in clearly defined keep-out zones, avoid components that trap coating (tall parts next to fine-pitch parts), and specify the coating type and thickness on the assembly drawing. Comtec Labs checks these during the DFM review and proposes the coating programme with the quote.
Frequently asked questions
Does conformal coating make a PCB waterproof?
No. It protects against condensation, humidity and contamination. Immersion or pressure washing needs a sealed enclosure or potting.
Can a coated board be repaired?
Yes. Acrylic is removed locally with solvent or heat, reworked and recoated. Urethane and silicone are harder to remove, so design for fewer field repairs.
How is coating quality checked?
Under UV light, since coating materials carry a UV tracer, plus thickness measurement on test coupons and adhesion checks per IPC-CC-830.
Does Comtec Labs coat boards it did not assemble?
Yes, coating is offered as a stand-alone service for boards assembled elsewhere, subject to an incoming inspection.
Ready to reduce PCB surprises?
Comtec Labs offers a full suite of services to streamline your workflow:
PCB design service
PCB prototyping service
PCB component sourcing
PCB component assembly
PCB testing service
PCB repair and modifications
Printed circuit board production
PCB mass production