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HumiSeal 1B31-LOC Acrylic Conformal Coating

HumiSeal® 1B31LOC is a low VOC solvent based conformal coating that complies with most North American air quality regulations. HumiSeal® 1B31LOC is a fast drying, single component, acrylic coating that provides excellent moisture and environmental protection for printed circuit assemblies. HumiSeal® 1B31LOC demonstrates excellent flexibility and electrical properties, fluoresces under UV light for ease of inspection and is easily repaired. HumiSeal® 1B31LOC coating is MIL-I-46058C qualified, and IPC-CC-830 and RoHS Directive 2002/95/EC compliant.
Manufacturer: Humiseal

Properties HumiSeal® 1B31LOC

Density, per ASTM D1475 1.20 ± 0.03 g/cm³
Solids Content, % by weight per Fed-Std-141, Meth. 4044 25 ± 3 %
Viscosity, per Fed-Std-141, Meth. 4287 450 ± 25 centipoise VOC 91 grams/litre Drying Time to Handle per Fed-Std-141, Meth. 4061 25 minutes Recommend 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 HumiSeal® Thinner 701
Recommended Stripper HumiSeal® Stripper 1080, 1080EU 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 below Tg
340 ppm/°C above Tg
Glass Transition Temperature - DSC 14°C
Modulus - DMA 2000 MPa @ -40°C
1050 MPa @ 20°C
8.5 MPa @ 60°C Flammability, per MIL-I-46058C Self-Extinguishing 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 2.5
Dissipation Factor, at 1MHz and 25°C per ASTM D150-98 0.01
Insulation Resistance, per MIL-I-46058C 8.0 x 1014 ohms (800TΩ) Moisture Insulation Resistance, per MIL-I-46058C 7.0 x 1010 ohms (60GΩ)
Fungus Resistance, per ASTM G21 Passes

Application HumiSeal® 1B31LOC

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® 1B31LOC with HumiSeal® Thinner 701 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 701. Viscosity in the dip tank should be checked regularly, using a simple measuring device such as a Zahn or Ford
viscosity cup.


HumiSeal® 1B31LOC 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 701 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


HumiSeal® 1B31LOC may be brushed with a small addition of HumiSeal® Thinner 701. Uniformity of the film depends on component density and operator's technique.


HumiSeal® 1B31LOC 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. Material should not be used in presence of open flame or sparks. Use only in well-ventilated areas to avoid inhalation of vapours or spray. Avoid contact with skin and eyes.

Consult MSDS/SDS prior to use.



Conro Electronics Ltd
Unit 7, Orbital 25, Dwight Road, Watford, Hertfordshire
WD18 9DA

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