Silfluo CC7900-150 is a single-component, solvent-free polyurethane acrylate conformal coating with a UV/moisture dual-cure mechanism. UV exposure initiates rapid free-radical crosslinking of the acrylate network; a secondary moisture-cure reaction proceeds in shadowed areas where UV light cannot penetrate, completing crosslinking without additional process steps.
The solvent-free formulation eliminates VOC emissions during application and cure. A built-in fluorescent UV tracer allows coverage inspection under 365 nm UV blacklight. The cured film achieves UL 94 V0 flame retardancy and an operating temperature range of −60°C to +135°C.
Applied to PCBs in smart metering, household consumer appliances, and automotive electronics to protect against moisture, condensation, salt spray, mildew, and corrosive gases. Elongation at break of 199% accommodates differential thermal expansion between the cured film and PCB substrate during thermal cycling from −60°C to +135°C without film cracking or delamination — relevant for automotive underhood and outdoor electronics applications.
2. Shadowed Component Protection
Dual-cure mechanism addresses the coverage limitation of UV-only coatings: components with shadowed areas (through-hole components, tall SMD components, connector housings) receive complete crosslinking via moisture cure without requiring repositioning for additional UV exposure passes. Basic cure in shadowed areas requires approximately 3 days at 23°C / 50% RH; ultimate mechanical and electrical properties are reached in 7–14 days.
Typical Uncured Liquid Properties of LC-CC7900-150D Conformal Coating
Base Material
Polyurethane acrylate
Color
Colorless to pale yellow liquid
Viscosity(mPa.s)
150
Specific gravity (@23℃)
1.10
Surface dry energy (mJ/cm2)
1000
Cured Film Profile & Electrical Properties of LC-CC7900-150D Conformal Coating
Adhesion (Cross-Cut Test)
Class 0 (Excellent)
Hardness(Shore A)
60
Tensile Strength(MPa)
3.57
Elongation At Break(%)
199
Volume resistivity (ohm-cm)
3.7×1014
Dielectric constant (1MHz)
3.2
Dielectric strength (KV/mm)
23
Surface resistance (ohm)
4.3×1014
Flame retardant grade (UL 94)
V0
Operating temperature (℃)
-60~135
Standard conditions: temperature 23±2℃, relative humidity 50±5%RH.
Application & Curing Guidelines of LC-CC7900-150D Conformal Coating
Surface Preparation
Clean PCB surfaces of all flux residues, dust, grease, fingerprints, and ionic contaminants before coating. Verify cleanliness by ion contamination test (IPC-TM-650 2.3.25 or equivalent) on critical assemblies.
Application Methods
Manual brushing, automated selective spray coating, and dip coating. If material has been agitated, allow to stand until air bubbles dissipate before application. Maintain boards in horizontal position during coating and initial UV cure to prevent wet film flow on vertical surfaces.
UV Cure
Expose coated boards to UV light at the wavelength and intensity specified for the UV lamp system in use. Minimum surface dry energy: 1,000 mJ/cm². Actual cure speed depends on UV intensity (mW/cm²), wavelength, film thickness, and lamp-to-substrate distance — verify cure state by tack test after UV exposure. Tack-free state is reached immediately after adequate UV dose.
Moisture Cure (Shadowed Areas)
Moisture cure proceeds automatically at ambient conditions after UV exposure. Basic cure: approximately 3 days at 23°C / 50% RH. Ultimate properties (tensile strength, elongation, electrical): 7–14 days at 23°C / 50% RH. Higher temperature and relative humidity accelerate moisture cure rate; below 40% RH or below 15°C, extend cure time accordingly.
Multi-Layer Application
Apply second coat only after the first layer is fully tack-free following UV exposure. Do not apply over wet or partially moisture-cured films.
Inspection
Inspect under 365 nm UV blacklight after UV cure to verify coating coverage and identify skipped areas or pinholes. Rework uncured or inadequately covered areas by brush application before moisture cure begins in those zones.
Cleanup
Remove uncured material with IPA, MEK, or equivalent organic solvent before cure. Cured film removal requires mechanical abrasion or dedicated conformal coating remover.
Safety, Packaging & Storage of LC-CC7900-150D Conformal Coating
Packaging: Available in 1kg opaque containers.
Safety Precautions: Avoid skin contact with the uncured material. In case of eye contact, rinse immediately with plenty of water and seek medical attention.
Storage Conditions: Store tightly sealed in a cool, dry, and dark place. Maintain storage temperatures strictly between 8°C and 25°C.
Shelf Life: 6 months in original, unopened packaging.
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