1B31 EPA and 1B31 EPA Preblends

HumiSeal® 1B31EPA is a fast drying, single component, acrylic conformal coating that provides excellent moisture and environmental protection for printed circuit assemblies. 1B31EPA is also produced as pre-blended products, at a range of viscosities, suitable for a variety of applications The cured film demonstrates exceptional flexibility, fluoresces under UV light for ease of inspection and is easily repaired. HumiSeal® 1B31EPA coating is MIL-I-46058C qualified, IPC-CC-830, RoHS Directive 2011/65/EC and EPA 33/50 compliant.

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After complete cure, the properties of HumiSeal® 1B31EPA Pre-Blends and HumiSeal® 1B31EPA are comparable as all solvents evaporate during the drying process.

Cleanliness of the substrate is extremely important to the successful application of a conformal coating. Surfaces should be free of moisture, dirt, wax, grease and all other contaminants. Otherwise, ionic or organic residues on the substrate could be trapped under the coating and cause problems with adhesion or electrical properties. The highest long term reliability for a coated printed circuit assembly will be when the conformal coating is applied over a clean, dry substrate.

The application of conformal coatings over no clean flux is a common practice. The user should perform adequate testing to confirm compatibility between the conformal coating and their particular assembly materials and process conditions. Please contact HumiSeal 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® 1B31EPA with HumiSeal® Thinner 600 or 604 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 600 or 604. Viscosity in the dip tank should be checked regularly using a simple measuring device such as a Zahn or Ford viscosity cup.

HumiSeal® 1B31EPA 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 600 or 604 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® 1B31EPA to HumiSeal® Thinner 600 or 604 is 1:1 by volume; however the ratio may need to be adjusted to obtain a uniform coating.

HumiSeal® 1B31EPA may be brushed with a small addition of HumiSeal® Thinner 600 or 604. Uniformity of the film depends on component density and operator’s technique.

Product Specification

Product Viscosity, CPS Solids Content, % Density, g/cm³ VOC, g/L
1B31EPA 265.0 – 385.0 25.00 – 31.00 0.95 ± 0.03 684
1B31EPA/600 PB65 60.0 – 70.0 18.00 – 20.00 0.94 ± 0.01 761
1B31EPA/604 PB35 30.0 – 40.0 14.00 – 16.00 0.93 ± 0.01 786
Product Specification
Density, per ASTM, Meth. D1475 0.95 ± 0.03 g/cm³
Solids Content, % by weight per Fed-Std-141, Meth. 4044 28 ± 3 %
Viscosity, per Fed-Std-141, Meth. 4287 325 ± 60 centipoise
VOC 684 grams/litre
Drying Time to Handle per Fed-Std-141, Meth. 4061 30 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 (dipping, brushing) HumiSeal Thinner 604
Recommended Thinner (spraying) HumiSeal Thinner 600
Recommended Stripper HumiSeal Stripper 1080
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 6300 volts
Dielectric Constant, at 1MHz and 25°C, per ASTM D150-98 2.6
Dissipation Factor, at 1MHz and 25°C, per ASTM D150-98 0.01
Insulation Resistance, per MIL-I-46058C 5.5 x 1012 ohms (550TΩ)
Moisture Insulation Resistance, per MIL-I-46058C 7.0 x 1010 ohms (70GΩ)
Fungus Resistance, per ASTM G21 Passes