HumiSeal® 1B51NSLU is an air drying, single component, synthetic rubber conformal coating that contains methylcyclohexane solvent that is more environmentally friendly than traditional solvents. Because of its unique base polymer, HumiSeal® 1B51NSLU has extremely low moisture vapour permeability. The coating demonstrates excellent flexibility, low stress on components, fluoresces under UV for ease of inspection and is easily repaired. HumiSeal® 1B51NSLU is in full compliance with the RoHS Directive 2002/95/EC.

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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.

Depending on the complexity, density and configuration of components on the assembly, it may be necessary to reduce the viscosity of HumiSeal® 1B51NSLU with HumiSeal® Thinner 903 or 905 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 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 903 or 905. Viscosity in the dip tank should be checked regularly, using a simple measuring device such as a Zahn or Ford viscosity cup.

HumiSeal® 1B51NSLU can be sprayed using conventional spraying equipment. Spraying should be done in an environment with adequate ventilation so that the vapour and mist are carried away from the operator. The addition of HumiSeal® Thinner 903 or 905 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. The recommended ratio of HumiSeal® 1B51NSLU to HumiSeal® Thinner 903 or 905 is 1:1 by volume, however the quantities may need to be adjusted to obtain a uniform coating.

HumiSeal® 1B51NSLU may be brushed with a small addition of HumiSeal® Thinner 903 or 905. Uniformity of the film depends on component density and operator’s technique.

Product Specification

Product Specification
Density, per ASTM D1475 0.81 ± 0.02 g/cm3
Solids Content, % by weight per Fed-Std-141, Meth. 4044 22 ± 2 %
Viscosity, per Fed-Std-141, Meth. 4287 185 ± 30 centipoise
VOC 632 grams/litre
Drying Time to Handle per Fed-Std-141, Meth. 4061 10 minutes
Recommended Coating Thickness 25 – 75 microns
Recommended Curing Conditions 24 hrs @ RT or 30 min @ 76°C
Time Required to Reach Optimum Properties 7 days
Recommended Thinner Thinner 903, 905, 521EU
Recommended Stripper Stripper 1080, 1080EU
Shelf Life at Room Temperature, DOM 18 months
Thermal Shock, 50 cycles per MIL-I-46058C -65°C to 125°C
Coefficient of Thermal Expansion – TMA 55 ppm/°C
Glass Transition Temperature – DSC 14°C
Modulus – DMA 93.1 MPa @ -20°C73.5 MPa @ 0°C35.3 MPa @ 20°C
Moisture Vapour Transmission, per ASTM E398-03 <1 g/m2·day·mil
Dielectric Withstand Voltage, per MIL-I-46058C >1500 volts
Dielectric Breakdown Voltage, per ASTM D149 4900 volts
Dielectric Constant, at 1MHz and 25°C per ASTM D150-98 2.5
Dissipation Factor, at 1MHz and 25°C per ASTM D150-98 0.07
Insulation Resistance, per MIL-I-46058C 2.0 x 1014 ohms (200TΩ)
Moisture Insulation Resistance, per MIL-I-46058C 1.0 x 1010 ohms (10GΩ)
Fungus Resistance, per ASTM G21 Passes