HumiSeal® UV500-2 UV Curable Conformal Coating

HumiSeal® UV500-2

HumiSeal® UV500-2 is a high solids UV dual cure elastomeric acrylate conformal coating, with higher flexibility compared to other UV curable conformal coatings. Its formula is based on HumiSeal UV500 and is formulated at higher viscosity to allow use with alternate application systems, and also to reduce capillarity and flow.

HumiSeal® UV500-2 is tack free after exposure to UV light and the secondary moisture cure mechanism will fully cure any unexposed areas of the coating within 7 days at ambient conditions.

After full cure, HumiSeal® UV500-2 exhibits:

  • Excellent
  • Excellent moisture
  • Highly stable electrical insulation
  • Good chemical
  • Excellent performance in thermal cycling
  • Fluorescence under UV light to allow coating

HumiSeal® UV500-2 meets the following standards:

  • IEC 61086 Class 2
  • HKMC MS941-04
  • BMW group standard GS 95011-5.
  • UL94 V1
  • Compliant with EU RoHS Directive 2015/863
  • Compliant with China RoHS 2
  • Compliant to China Standard GB30981-2020

Properties of HumiSeal® UV500-2 Liquid Coating

Density 1.0 to 1.1 g/cm3
Minimum Solids Content 98%
Viscosity, per Fed-Std-141, Meth. 4287 400 to 600 centipoise
Shelf Life at Room Temperature, DOM 9 Months


Properties of HumiSeal® UV500-2 Cured Coating

Recommended Coating Thickness 25 – 125 microns
Recommended UV Cure See Curing Below
Time to reach optimum properties 7 days after UV cure
Operating temperature range -65°C to 150°C
Thermal Shock, 1000cycles -65°C to 150°C
Glass Transition Temperature – DSC -43°C
 Coefficient of Thermal Expansion – TMA  137ppm/°C Below Tg
311ppm/°C Above Tg
Modulus – DMA  0.4MPa @ 25°C
 Thermal Conductivity 0.505 W/mK
Dielectric Withstand Voltage (Per MIL-I-46058C) >1500V
Dielectric Constant at 10GHz and 22C Per ASTM-D2520  >3.07
 Dissipation Factor at 10GHz and 22C Per ASTM-D2520 0.03
 Surface Insulation Resistance (per IPC J-STD-004 (mod.)) 9.0 log10 ohms
Damp Heat Insulation Resistance (40C/90% RH)  >10.3 log10 ohms
Salt Spray Resistance (Per IEC60068-2-11)  Passes
Resistance to Chemicals Good

Application of HumiSeal® UV500-2 HumiSeal®

Conformal coatings can be successfully applied to substrates that have been cleaned prior to coating and also to substrates assembled with low residue, “no clean” assembly materials. Users should perform adequate testing to confirm compatibility between the conformal coating and their particular assembly materials, process conditions and cleanliness level. Please contact HumiSeal® for additional information.


HumiSeal® UV500-2 can be applied via standard selective coating equipment or by conventional hand spray equipment. The source air used for spraying must be dry (a dry air supply or dry inert gas (nitrogen or argon) is highly recommended) to prevent premature curing of the secondary cure mechanism. The spraying should be done with adequate ventilation so that the vapor and mist are carried away from the operator.


HumiSeal® UV500-2 may be applied by brush for rework or touch up only. Brush must be cleaned with solvent promptly after use.


HumiSeal® UV500-2 is a highly crosslinked coating. In order to achieve maximum crosslinking density, the product must be exposed to the correct spectral output. HumiSeal has modelled the performance of UV500-2 using Arc and Microwave based UV curing equipment. The table below outlines the minimum required dosage and irradiance values necessary to render HumiSeal® UV500-2 tack free post UV exposure with both equipment types. These figures should provide a tack free surface. HumiSeal recommend that these figures are for guidance only, and users should assess exact cure requirements with their own systems. These cure recommendations may change as curing technology develops.


Minimum Dose J/cm2* Minimum Irradiance W/cm2*
Arc System 2.8 2.8 0.45 1.1 1.1 0.2
Microwave System 3.0 3.0 0.5 1.15 1.15 0.24

*Values measured with a Powerpuck II UV radiometer

Heat is also an important component with UV cure, and different systems produce different heat outputs. Higher heat levels allow UV cure at lower dose/irradiance levels. Consequently, HumiSeal recommend that curing is discussed with HumiSeal® Technical staff to ensure the exact customer process being used will meet the coating cure requirements. After UV exposure and return to room temperature the coating should be tack free.

HumiSeal® UV500-2 contains a reliable secondary moisture cure mechanism which will cure any shadow areas on the assembly within 7 days at ambient moisture.

Clean Up

To flush equipment and clean uncured HumiSeal® UV500-2, non-alcohol based solvents should be used. HumiSeal® Thinner 521 or Thinner 521EU is recommended.


HumiSeal® UV500-2 is a highly crosslinked UV cured coating. The cured film has a high degree of environmental and chemical resistance and will be more difficult to remove than traditional conformal coatings. Thermal displacement and mechanical abrasion are suitable options for rework of HumiSeal® UV500-2.


HumiSeal® UV500-2 is photosensitive. The product should not be exposed to direct sunlight or full spectrum fluorescent lighting. HumiSeal® UV500-2 should be stored cool below 20°C, to maximize shelf life. Prior to use, allow the product to equilibrate for 24 hours at room temperature. HumiSeal® UV500-2 is a moisture curing material and care should be taken to protect process vessels and partial containers from moisture.

Partial containers must be purged with a dry, inert gas such as dry air, nitrogen or argon before closure, otherwise premature polymerization by atmospheric moisture will occur.


Application of HumiSeal® Conformal Coatings should be carried out in accordance with local and National Health and Safety regulations.

Use only in well-ventilated areas to avoid inhalation of vapours or spray. Avoid contact with skin and eyes. Consult SDS prior to use.

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