HumiSeal® 1B51 is a fast drying, single component, synthetic rubber conformal coating that provides excellent moisture and environmental protection for printed circuit assemblies. Because of its unique base polymer, HumiSeal® 1B51 has extremely low moisture vapour permeability. The coating demonstrates excellent flexibility, low stress on components and is easily repaired. HumiSeal® 1B51 is in full compliance with the RoHS Directive 2002/95/EC.
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® 1B51 with HumiSeal® Thinner 535 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 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 535. Viscosity in the dip tank should be checked regularly, using a simple measuring device such as a Zahn or Ford viscosity cup.
HumiSeal® 1B51 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® 1B51 to HumiSeal® Thinner 521 or 521EU is 1:1 by volume; however the quantities may need to be adjusted to obtain a uniform coating.
HumiSeal® 1B51 may be brushed with a small addition of HumiSeal® Thinner 535. Uniformity of the film depends on component density and operator’s technique.
|Density, per ASTM D1475||0.89 ± 0.01 g/cm3|
|Solids Content, % by weight per Fed-Std-141, Meth. 4044||22 ± 1.5 %|
|Viscosity, per Fed-Std-141, Meth. 4287||185 ± 30 centipoise|
|Drying Time to Handle per Fed-Std-141, Meth. 4061||10 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 535|
|Recommended Thinner (spraying)||HumiSeal Thinner 521, 521EU|
|Recommended Stripper||HumiSeal Stripper 1080, 1080EU|
|Shelf Life at Room Temperature, DOM||18 months|
|Thermal Shock, 50 cycles per MIL-I-46058C||-65°C to 125°C|
|Coefficient of Thermal Expansion – TMA||55 ppm/°C|
|Glass Transition Temperature – DSC||14°C|
|Modulus – DMA||93.1 MPa @ -20°C73.5 MPa @ 0°C35.3 MPa @ 20°C|
|Moisture Vapor Transmission, per ASTM E398-03||<1 g/m2·day·mil|
|Dielectric Withstand Voltage, per MIL-I-46058C||>1500 volts|
|Dielectric Breakdown Voltage, per ASTM D149||4900 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||0.07|
|Insulation Resistance, per MIL-I-46058C||2.0 x 1014 ohms (200TΩ)|
|Moisture Insulation Resistance, per MIL-I-46058C||1.0 x 1010 ohms (10GΩ)|
|Fungus Resistance, per ASTM G21||Passes|