Urethanes 1A27 LTX

HumiSeal® 1A27 LTX conformal coating is:

  • Urethane chemistry
  • Polyurethane conformal coating
  • Single component
  • Suitable for general printed circuit board applications
  • Formulated with reduced xylene and toluene concentration to be fully compliant with GB30981-2020
  • RoHS Directive 2011/65/EU compliant and recognized under UL File Number E105698

HumiSeal 1A27 LTX conformal coating has:

  • Protection against moisture, corrosive environments, and dirt
  • Easy application with automated systems.
  • Low moisture vapor permeability.
  • Range of preblends thinners available for different application methods
  • Compliant with GB30981-2020

Application of 1A27 LTX Conformal Coating

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.

Technical Support should be contacted if any further advice on Pre-blend Products and equipment is required.


Depending on the complexity, density and configuration of components on the assembly, it may be necessary to reduce the viscosity of  HumiSeal® 1A27  LTX with  HumiSeal® Thinner  789  in order to obtain a  uniform film.  Once optimum viscosity is determined, a controlled rate of immersion and withdrawal (5-15 cm/min) will further ensure even deposition of the coating and ultimately a uniform film.  During the application, evaporation of solvent causes an increase in viscosity that should be adjusted by adding small amounts of HumiSeal® Thinner 789. Viscosity in the dip tank should be checked regularly, using a simple measuring device such as a Zahn or Ford viscosity cup.


HumiSeal® 1A27 LTX can be sprayed using conventional spraying equipment.  Spraying should be done in an environment with adequate ventilation so that the vapor and mist are carried away from the operator.  The addition of HumiSeal® Thinner 789 is necessary to ensure a uniform spray pattern resulting in pinhole-free film.  The amount of thinner and spray pressure will depend on the specific type of spray equipment used and operator technique.


HumiSeal® 1A27 may be applied by brush with a small addition of HumiSeal Thinner 789. The uniformity of the film depends on the component density and the operator’s technique.


HumiSeal® 1A27 LTX should be stored away from excessive heat or cold, in tightly closed containers. HumiSeal® products may be stored at temperatures of 0 to 35°C. Prior to use, allow the product to equilibrate for 24 hours at a room temperature of 18 to 32°C.


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

The solvents in HumiSeal® Conformal Coatings are flammable. The material should not be used in presence of open flame or sparks. Use only in well-ventilated areas to avoid inhalation of vapors or spray.  Avoid contact with skin and eyes.



Product Specification

Density, per ASTM D1475 0.96 ± 0.02 g/cm3
Solids Content, % by weight per Fed-Std-141, Meth. 4044 50 ± 3 %
Viscosity, per Fed-Std-141, Meth 4287 3000 ± 1000 centipoise
VOC 480 grams/liter
Recommended Coating Thickness 25 – 75 microns
Drying Time to Handle per Fed-Std-141, Meth. 4061 30 minutes
Optional Curing Conditions to Reach Optimum Properties 30 days @ RT

30 hours @ 76°C

20 hours @ 88°C

Recommended Thinner HumiSeal ® Thinner 789
Recommended Stripper HumiSeal® Stripper 1063
Shelf Life at Room Temperature, DOM 24 Months
Thermal Shock, 50 cycles per MIL-I-46058C -65°C to 125°C
Coefficient of Thermal Expansion – TMA 170 ppm/°C
Glass Transition Temperature – DSC 28°C
Modulus – DMA 18.1 MPa
Flammability, per UL 94 V-0
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 3.6
Dissipation Factor, at 1MHz and 25°C, per ASTM D150-98 0.02
Insulation Resistance, per MIL-I-46058C 2.0 x 1014 ohms (200TΩ)
Moisture Insulation Resistance, per MIL-I-46058C 1.2 x 1010 ohms (12GΩ)