1A33

HumiSeal® 1A33 is a single component, polyurethane conformal coating, suitable for general printed circuit board applications. HumiSeal® 1A33 contains no free isocyanates and fluoresces under UV light for inspection purposes. HumiSeal® 1A33 coating is MIL-I-46058C qualified, IPC-CC-830 and RoHS Directive 2011/65/EC compliant and recognized under UL File Number E105698.

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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.

Dipping
Depending on the complexity, density and configuration of components on the assembly, it may be necessary to reduce the viscosity of HumiSeal® 1A33 with HumiSeal® Thinner 503 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 503. Viscosity in the dip tank should be checked regularly, using a simple measuring device such as a Zahn or Ford viscosity cup.

Spraying
HumiSeal® 1A33 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 or 521EU 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® 1A33 to HumiSeal® Thinner 521 or 521EU is 1:1 by volume; however the ratio may need to be adjusted to obtain a uniform coating.

Brushing
HumiSeal® 1A33 may be applied by brush. Uniformity of the film depends on component density and operator’s technique.

Product Specification

Product Specification
Density, per ASTM D1475 0.95 ± 0.02 g/cm3
Solids Content, % by weight per Fed-Std-141, Meth. 4044 44 ± 2 %
Viscosity, per Fed-Std-141, Meth. 4287 180 ± 20 centipoise
VOC 531 grams/lire
Recommended Coating Thickness 25 – 75 microns
Drying Time to Handle per Fed-Std-141, Meth. 4061 15 minutes
Optional Curing Conditions to Reach Optimum Properties 30 days at RT30 hours @ 76°C

20 hours @ 88°C

Recommended Thinner (dipping, brushing) HumiSeal Thinner 503
Recommended Thinner (spraying) HumiSeal Thinner 521, 521EU
Recommended Stripper HumiSeal Stripper 1063
Shelf Life at Room Temperature, DOM 24 months
Thermal Shock, 50 cycles per MIL-I-46058C -65° to 125°C
Coefficient of Thermal Expansion – TMA 193 ppm/°C
Glass Transition Temperature – DSC 26°C
Modulus – DMA 27.2 MPa
Flammability, per UL 94 V-0
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 3.6
Dissipation Factor, at 1MHz and 25°C per ASTM D150-98 0.03
Insulation Resistance, per MIL-I-46058C 2.0 x 1014 ohms (200TΩ)
Moisture Insulation Resistance, per MIL-I-46058C 1.6 x 1010 ohms (16GΩ)
CTI, PLC per UL746A @ 600 volts 0
Fungus Resistance, per ASTM G21 Passes