PCB Conformal Coating Services
Protect your assembled circuit boards from moisture and contamination with FLJ’s acrylic, urethane and silicone conformal coating services. We prepare, mask, coat and cure your PCBAs, keeping the required connections accessible while protecting the surrounding circuitry.
Coating is available as part of Osazení desek plošných spojů or for populated boards supplied for finishing, from prototypes to production runs.
Protection for Electronics in Demanding Environments
Moisture and surface contamination can turn an exposed circuit into a path for leakage current and corrosion. A conformal film covers the board’s contours, soldered connections and component surfaces, reducing their direct exposure to the operating environment.
An industrial controller may face airborne contamination inside a cabinet. Outdoor lighting and sensor electronics may experience humid air and condensation as temperatures change. These different exposures help determine the coating material and the areas that need protection.
After soldering, the assembled board is cleaned, dried and inspected before coating. The cured film protects component surfaces, solder joints and exposed circuitry from moisture and contamination.
Conformal coating also has a different job from a bare board’s solderable PCB surface finishes. It protects the populated assembly rather than preparing its pads for soldering.
Acrylic, Urethane and Silicone Coating Options
The operating environment and future service access guide material choice. A board that needs routine component replacement benefits from a removal-friendly coating. A board exposed to aggressive chemicals may need a more resistant film, with a different approach to later repair. Flexibility becomes another consideration when the assembly experiences temperature changes.
| Materiál | Useful characteristics | A practical selection consideration |
|---|---|---|
| Acrylic — AR | Fast processing and relatively straightforward local removal; widely used for general environmental protection. | Useful when later access to components and solder joints is important. |
| Urethane — UR | Chemical and abrasion resistance in a durable film. | Solvent resistance can make removal more demanding. |
| Silicone — SR | A flexible film suited to assemblies that need temperature tolerance. | Balance flexibility, adhesion, abrasion exposure and the required removal method. |
Scroll sideways to compare the materials →
Products within the same resin family can differ in adhesion, chemical resistance and cure requirements. We select the formulation to suit the board materials, operating environment and any planned component repairs.
UV curing describes a processing route, while acrylic, urethane and silicone describe material chemistry. Parylene uses vapor deposition rather than the liquid application methods described below. These distinctions matter when comparing coating options and planning production.
Selective Coverage Around Connectors, Contacts and Test Points
A · Intended protective film
Circuit surfaces and the specified component and soldered areas.
B · Required clear interfaces
Contact faces and access points identified for the product.
Illustrative coverage plan. Board shape and features are schematic.
Connector housings and soldered connections can need coating even when the mating contacts must remain clear. A coating drawing or annotated board image identifies these boundaries before application.
We mask connector contacts, test points and other areas that must remain free of coating. During selective spraying, the spray path, angle and flow are adjusted to reach around components and control coverage at the masked edges.
After application, we check coverage against the drawing and confirm that the specified contact surfaces remain clear.
From a Clean Assembly to a Cured Protective Film
A stable film starts at the board surface. We address oil, dust, incompatible process residues and retained moisture before application. The aim is a clean, dry surface that the selected coating can wet and adhere to. The preparation method accounts for the board’s components and material compatibility.
The board’s geometry determines how material reaches the circuit. Selective spray follows programmed areas around components and defined boundaries. Dip coating immerses the assembly in liquid, making masking, withdrawal and drainage important to the resulting film. Brush application provides direct access to a small area, including a local coating repair.
A setup sample or suitable witness coupon helps establish application conditions before the production run. The coating formulation, deposited amount and cure route are treated together, rather than using one recipe for every board.
Curing develops the intended film properties. Depending on the material, this may involve solvent evaporation, moisture, heat or UV exposure. A surface that is dry enough to handle can still require further cure before final property checks or shipment.
Coverage, Film Thickness and Local Rework
Coverage inspection follows the intended protective area and the masked boundaries. Where the material contains a fluorescent tracer, UV illumination helps reveal missed areas and coating on locations that should remain clear. Visual examination also looks for coating defects such as bubbles, voids and excessive buildup.
Film thickness is specified in micrometres. A liquid-coating range such as 25–75 μm corresponds to 0.025–0.075 mm: a useful illustration of the thin film involved. The production target comes from the selected material and application, rather than this example range.
Wet-film checks support application control, while dry-film measurement evaluates the resulting layer. With a solvent-borne material, carrier evaporation changes the film between these stages. The measurement method and location need to suit the coating, board geometry and film scale.
Fluorescence shows where a tracer-bearing coating is visible under UV illumination. Thickness measurement and cure verification establish other aspects of the film. Electrical or environmental checks, where included in the product’s PCB testing plan, assess their defined performance conditions.
For a local repair, we uncover the affected component or solder joint using a removal method compatible with the coating and nearby parts. After the repair, the disturbed area is cleaned and prepared for fresh coating. Restoring the specified coverage, curing it and checking the repaired area complete the protective finish. The resin’s resistance to removal is therefore part of the maintenance decision made earlier.