Urethane 1A27

HumiSeal® 1A27 conformal coating is:

  • Urethane chemistry
  • chemically resistant
  • single component
  • contains no free isocyanates
  • used in combination with Thinner 521
  • RoHS directive 2015/863/EU
  • recognized under UL File Number E105698.

HumiSeal 1A27 conformal coating has:

  • excellent moisture and environmental protection for printed circuit assemblies
  • RoHS Directive 2002/95/EC compliance

Application of 1A27 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. Please contact a HumiSeal representative for additional information.

Depending on the complexity, density and configuration of components on the assembly, it may be necessary to reduce the viscosity of HumiSeal 1A27 with HumiSeal Thinner 521 in order to obtain a uniform film. Once optimum viscosity is determined, a controlled rate of immersion and withdrawal (typically, 5 to 15 cm/min) will further ensure even deposition of the coating and provide a uniform film. During application, evaporation of solvent causes an increase in viscosity that should be adjusted by adding small amounts of HumiSeal® Thinner 521. Viscosity in the dip tank should be checked regularly using a simple measuring device, such as a Zahn or Ford viscosity cup.

HumiSeal 1A27 can be sprayed using conventional spraying equipment. Spraying should be done in an environment with adequate ventilation so that vapor and mist are carried away from the operator. The addition of HumiSeal® Thinner 521 is necessary to ensure a uniform spray pattern resulting in a pinhole-free film. The amount of thinner and spray pressure will depend on the specific type of spray equipment and operator technique. The recommended ratio of HumiSeal 1A27 to HumiSeal Thinner 521 is 1:1 by volume; however the ratio may need to be adjusted to obtain a uniform coating.

HumiSeal 1A27 may be brushed with a small addition of HumiSeal Thinner 521. Uniformity of the film depends on the component density and operator technique.

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/litre
Recommended Coating Thickness 25 – 75
Drying Time to Handle per Fed-Std-141, Meth. 4061 30 minutes
Optional Curing Conditions to Reach Optimum Properties 30 days at RT

30 hours @ 76°C

20 hours @ 88°C

Recommended Thinner (spraying) HumiSeal Thinner 521
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 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)
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