1A27
HumiSeal® 1A27 is a single component, polyurethane conformal coating, suitable for general printed circuit board applications. HumiSeal® 1A27 contains no free isocyanates. HumiSeal® 1A27 coating is RoHS Directive 2002/95/EC compliant and recognized under UL File Number E105698.
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.
Dipping
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 (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 521. Viscosity in the dip tank should be checked regularly, using a simple measuring device such as a Zahn or Ford viscosity cup.
Spraying
HumiSeal® 1A27 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 521 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® 1A27 to HumiSeal® Thinner 521 is 1:1 by volume; however the ratio may need to be adjusted to obtain a uniform coating.
Brushing
HumiSeal® 1A27 may be applied by brush with a small addition of HumiSeal Thinner 521. Uniformity of the film depends on component density and operator’s technique.
Product Specification
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Product Specification
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Density, per ASTM D1475
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0.96 ± 0.02 g/cm³
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Solids Content, % by weight per Fed-Std-141, Meth. 4044
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50 ± 3 %
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Viscosity, per Fed-Std-141, Meth. 4287
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3000 ± 1000 centipoise
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VOC
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480 grams/litre
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Recommended Coating Thickness
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25 – 75
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Drying Time to Handle per Fed-Std-141, Meth. 4061
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30 minutes
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Optional Curing Conditions to Reach Optimum Properties
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30 days at RT
30 hours @ 76°C
20 hours @ 88°C
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Recommended Thinner (spraying)
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HumiSeal Thinner 521
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Recommended Stripper
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HumiSeal Stripper 1063
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Shelf Life at Room Temperature, DOM
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24 months
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Thermal Shock, 50 cycles per MIL-I-46058C
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-65° to 125°C
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Coefficient of Thermal Expansion – TMA
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170 ppm/°C
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Glass Transition Temperature – DSC
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28°C
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Modulus – DMA
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18.1 MPa
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Flammability, per UL 94
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V-0
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Dielectric Withstand Voltage, per MIL-I-46058C
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>1500 volts
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Dielectric Breakdown Voltage, per ASTM D149
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7500 volts
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Dielectric Constant, at 1MHz and 25°C per ASTM D150-98
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3.6
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Dissipation Factor, at 1MHz and 25°C per ASTM D150-98
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0.02
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Insulation Resistance, per MIL-I-46058C
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2.0 x 1014 ohms(200TΩ)
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Moisture Insulation Resistance, per MIL-I-46058C
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1.2 x 1010 ohms (12GΩ)
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