Synthetic Rubber 1B51

HumiSeal® 1B51 conformal coating is:

  • a fast drying
  • single component
  • synthetic rubber
  • used in combination with Thinner 535/521/521 EU

HumiSeal 1B51 conformal coating has:

  • excellent moisture and environmental protection for printed circuit assemblies
  • extremely low moisture vapor permeability
  • excellent flexibility, enabling low stress on components
  • full compliance with the RoHS directive 2015/863/EU
  • recognition under UL File Number E105698

Application of HumiSeal® 1B51

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® 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 vapor 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 a 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 the operator’s technique.

Product Specification
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
VOC 694 grams/litre
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
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