Urethanes Conformal coating 1A33
Model No: 1A33

HumiSeal® 1A33 is a single component, polyurethane conformal coating, suitable for general printed circuit board applications. HumiSeal® 1A33 contains no free isocyanates and fluorescence under UV light for inspection purposes. Cleanliness of the substrate is of extreme importance for the successful application of a conformal coating. Surfaces must be free of moisture, dirt, wax, grease, flux residues and all other contaminants. Contamination under the coating could cause problems that may lead to assembly failures.

 Product Enquiry

HumiSeal® 1A33 conformal coating is:

  • Urethane chemistry
  • chemically resistant
  • single component
  • contains no free isocyanates
  • used in combination with Thinner 503/521
  • MIL-I-46058C qualified
  • RoHS Directive 20115/863/EU
  • Recognized under UL File Number E105698


HumiSeal® 1A33 conformal coating has:

  • excellent moisture and environmental protection for printed circuit assemblies
  • fluorescence under UV light for ease of inspection


Application of HumiSeal® 1A33 Conformal Coating

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” materials. Users should perform adequate testing to confirm compatibility between the conformal coating and their particular assembly materials, process conditions and cleanliness level.


Product Specification

Density, per ASTM D1475

0.95 ± 0.02 g/cm3

Solids Content, % by weight per Fed-Std-141, Meth. 4044

44 ± 2 %

Viscosity, per Fed-Std-141, Meth. 4287

180 ± 20 centipoise


531 grams/lire

Recommended Coating Thickness

25 – 75 microns

Drying Time to Handle per Fed-Std-141, Meth. 4061

15 minutes

Optional Curing Conditions to Reach Optimum Properties

30 days at RT30 hours @ 76°C

20 hours @ 88°C

Recommended Thinner (dipping, brushing)

HumiSeal Thinner 503

Recommended Thinner (spraying)

HumiSeal Thinner 521, 521EU

Recommended Stripper

HumiSeal Stripper 1063

Shelf Life at Room Temperature, DOM

24 months

Thermal Shock, 50 cycles per MIL-I-46058C

-65° to 125°C

Coefficient of Thermal Expansion – TMA

193 ppm/°C

Glass Transition Temperature – DSC


Modulus – DMA

27.2 MPa

Flammability, per UL 94


Dielectric Withstand Voltage, per MIL-I-46058C

>1500 volts

Dielectric Breakdown Voltage, per ASTM D149

 7500 volts

Dielectric Constant, at 1MHz and 25°C per ASTM D150-98


Dissipation Factor, at 1MHz and 25°C per ASTM D150-98


Insulation Resistance, per MIL-I-46058C

2.0 x 1014 ohms (200TΩ)

Moisture Insulation Resistance, per MIL-I-46058C

1.6 x 1010 ohms (16GΩ)

CTI, PLC per UL746A @ 600 volts


Fungus Resistance, per ASTM G21