HumiSeal® 1B73 is a single component, fast drying, acrylic conformal coating intended for use on printed circuit assemblies. HumiSeal® 1B73 demonstrates excellent flexibility and electrical properties, fluoresces under UV light for ease of inspection and is easily repaired. HumiSeal® 1B73 coating is MIL-I-46058C qualified, IPC-CC-830 and RoHS Directive 2011/65/EU compliant, and recognized under UL File Number E105698.

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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 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® 1B73 with HumiSeal® Thinner 73 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 73. Viscosity in the dip tank should be checked regularly, using a simple measuring device such as a Zahn or Ford viscosity cup.

HumiSeal® 1B73 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 73 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® 1B73 to HumiSeal® Thinner 73 is 1:1 by volume; however the ratio may need to be adjusted to obtain a uniform coating.

HumiSeal® 1B73 may be brushed with a small addition of HumiSeal® Thinner 73. Uniformity of the film depends on component density and operator’s technique.

Product Specification

Product Specification
Density, per ASTM D1475 0.92 ± 0.02 g/cm³
Solids Content, % by weight per Fed-Std-141, Meth. 4044 29.5 ± 2 %
Viscosity, per Fed-Std-141, Meth. 4287 250 ± 20 centipoise
VOC 661 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 2 hrs @ 76°C
Time Required to Reach Optimum Properties 7 days
Recommended Thinner HumiSeal® Thinner 73
Recommended Stripper HumiSeal® Stripper 1080, 1080A
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 67 ppm/°C
Glass Transition Temperature – DSC 42°C
Modulus – DMA 11.1 MPa
Flammability, per UL 94 V-0
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 0.010
Insulation Resistance, per MIL-I-46058C 5.5 x 1014 ohms (550TΩ)
Moisture Insulation Resistance, per MIL-I-46058C 7.0 x 1010 ohms (70GΩ)
Fungus Resistance, per ASTM G21 Passes