Conformal coating is one of the most natural jobs for a UV conveyor curing system: boards leave the coater one after another, and a belt carries them under the lamp at a set speed. The hard part is not moving the boards — it is making sure every coated area, including the shadowed ones, actually cures.
Q: How do you cure conformal coating on a UV conveyor?
A: Match the lamp head width to the board or panel lane, set belt speed to deliver the coating’s required dose, use an anti-static belt for populated boards, and plan for shadowed areas under tall components — either with a dual-cure coating whose secondary mechanism finishes those regions, or with process steps that verify they are covered and cured.
Match the Lamp Head to the Panel
On Incure’s CDM™ conveyor, LED flood heads suit board coating because they expose a whole area at once:
- L64 — a 6″ × 4″ flood footprint sized for the standard 4-inch PCB panel lane, with up to 4 inches of part width. The 6-inch length runs along the belt; the 4-inch width bounds the lane so dose is not spent on belt or fixture outside the panel.
- L88 — an 8″ × 8″ footprint with up to 8 inches of part width, for wider panels, irregular boards, or multiple rows.
Both deliver 1,900 mW/cm² at 385/395/405 nm (1,600 mW/cm² at 365 nm) at a 2-inch working distance. The wider L88 is not a stronger version of the L64; it trades lane fit for width. On a dedicated 4-inch panel line, the L64 avoids irradiating area the board never uses.
Use the Anti-Static Belt Option
The standard CDM™ runs a 9-inch polypropylene belt with an anti-static option. For populated electronics assemblies traveling on the belt, specify the anti-static version and keep it in the maintenance checks as the belt wears.
Set Speed From the Coating’s Dose
Belt speed on the CDM™ adjusts from 1.5 to 12.0 ft/min, and dose falls in proportion as speed rises. The L64’s published dose range is 4,750 mJ/cm² UVA at the fastest setting to 38,000 at the slowest; the L88 spans 6,325 to 50,600. Take the required dose from the coating’s data sheet, choose the speed that delivers it with margin for lamp decay — Incure rates LED heads past 20,000 hours with up to 20% decay — and confirm with a radiometer at board height.
Check the wavelength too. CDM™ LED heads are factory-configured to one wavelength (365, 385, 395, or 405 nm) at order, and the coating’s photoinitiator must cure at that wavelength.
Email Us with your board size, coating, and line speed, and Incure can recommend a head and speed setting.
Plan for Shadowed Areas
An overhead lamp cannot see underneath connector bodies or between closely spaced tall components. A UV-only coating can be left uncured in those regions, which leaves a path for moisture and contamination to the board. Two responses:
- Use a dual-cure coating. Incure’s Ultra-Illumina™ UV conformal coatings cure exposed surfaces with UV and finish shadowed material through a secondary heat-cure path. The 3511 grade runs 100–200 cP for flowing across populated boards; 3552 runs 300–600 cP; and 5454F is a thixotropic, non-sag gel at 11,000–22,000 cP for vertical boards and tall components.
- Inspect coverage directly. All three Ultra-Illumina™ grades fluoresce under UV black light, so an inspector can see thin or missing coating without a destructive cross-section.
Changing lamp height does not solve shadowing; it changes irradiance, not line of sight.
Lamp Height for Populated Boards
LED heads on the CDM™ adjust from 0.5 to 2.0 inches. Set height to clear the tallest component with margin, then measure irradiance at the coated surface, not at the belt. A board with tall connectors may sit closer to the lamp at its peaks than at its flat areas, so take readings where the critical coating sits.
Control and Traceability
LED heads on the CDM™ accept PLC, RS-232, and foot-switch inputs with timer or continuous modes. On a coating line, that supports interlocks such as lamp-on only when boards are present, and stored speed settings per board type. Pair controller records with periodic radiometer readings so each lot has both settings and measured output on file.
A Board-Line Checklist
- Head width matches the panel lane (L64) or the widest board (L88).
- Wavelength matches the coating.
- Anti-static belt specified.
- Speed set from the data-sheet dose with decay margin.
- Shadowed areas covered by dual cure or verified by inspection.
- Fluorescence inspection at the exit, where the coating supports it.
For the wider context, see the curing conveyor industrial guide; for every head’s dose table, the CDM™ lamp-head guide; and for the LED technology behind the L64 and L88, the Incure L-Series™ flood lamp guide.
Contact Our Team to set up conformal coating cure on a CDM™ conveyor.
Visit www.incurelab.com for more information.