UV Conformal-Coating Touch-Up & Repair
Every rework breaks the conformal coating around the repair. UV-cure conformal coatings let you re-coat just the reworked area and cure it in seconds, no oven cycle for the whole board, no hours of ambient cure blocking the line.
UV-cure conformal coatings gel on demand under a matched UV source. Touching up a reworked pad means brushing coating over the area and spot-curing only that patch, so the rest of the board is untouched and the board ships the same shift.
Touch-up is a portable, one-spot-at-a-time job, so the cordless handheld SkyWand (365 & 405 nm) goes to the board instead of the board coming to a bench. For high-volume re-coat at a rework station, the SunSpot 2 with a 5 mm guide cures faster and cures any coating chemistry.
Step by Step
- 1 Finish the rework and clean. Complete the solder rework and clean the area so the fresh coating adheres. Contamination under the coating is the usual cause of a re-coat that lifts.
- 2 Apply matched coating. Brush or dispense UV-cure conformal coating over the reworked area, feathering into the surrounding intact coating.
- 3 Spot-cure the patch. Bring the wand or guide over the patch and expose for the coating’s rated time, usually a few seconds. Only the patch cures; the rest of the board is untouched.
- 4 Check tack-free. Confirm the surface is tack-free. A tacky surface on an acrylate coating usually means it needs a little more dose to overcome oxygen inhibition at the very top layer.
Common Pitfalls
- Coating over contamination, clean the reworked area first or the re-coat lifts.
- A tacky top surface, acrylate coatings can stay slightly tacky from oxygen inhibition; add dose or use a coating formulated for open-air cure.
- Using the wand for large areas, for a whole reworked zone at a station, a bench SunSpot 2 is faster and covers more per exposure.
Questions
Can I repair conformal coating without re-baking the whole board?
Yes, that is the point of UV-cure conformal coating. Re-coat only the reworked area and spot-cure that patch in seconds; the rest of the board never sees the light or the heat.
What UV tool is best for conformal-coating touch-up in the field?
A cordless handheld wand like the SkyWand (365 & 405 nm) goes to the board wherever it is. For a fixed rework station handling volume, a bench SunSpot 2 with a 5 mm guide is faster.
Why is my UV conformal coating still tacky after curing?
A slightly tacky surface on an acrylate coating is usually oxygen inhibition of the top layer. Increase the dose, hold the source closer, or use a coating formulated for open-air UV cure.
