Silicone 1C55

HumiSeal® 1C55 conformal coating is:

  • silicone based
  • fluoresces under UV light
  • thermal cure
  • single component
  • high solids

HumiSeal 1C55 conformal coating has:

  • no VOCs or solvent
  • low toxicity
  • excellent environmental resistance and moisture resistance
  • RoHS directive 2015/863/EU

Application of 1C55 Silicone Conformal Coating

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 a HumiSeal representative for additional information.

1C55 is designed for application without additional thinning. Solvents or other thinners should not be mixed with 1C55. 1C55 may be applied by spray, brushing, flow coating or dipping. The time required to reach a tack free state is dependent on ambient conditions such as temperature and relative humidity. The processing guidelines contained in this document were obtained with an ambient relative humidity of 50%.


A controlled rate of immersion and withdrawal (5-15 cm/min) will ensure even deposition of the coating and ultimately a uniform film. Blanketing dip tanks with an inert gas such as nitrogen can extend pot life.


HumiSeal® 1C55 may be applied 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 use of thinner is not required or recommended for HumiSeal® 1C55.


Uniformity of the film depends on component density and operator’s technique.


HumiSeal® 1C55 is a thermally cured conformal coating. The actual curing temperature of HumiSeal® 1C55 is dependent upon several parameters such as heat sink characteristics of parts being coated, the type of oven used for curing process, as well as oven loading parameters. The cure mechanism for thermally cured silicones like HumiSeal® 1C55 may be inhibited by a variety of materials i.e.; amines, acrylates, certain ingredients from latex rubber etc. It is recommended that process and material compatibility be considered when incorporating HumiSeal® 1C55 into the production environment. Cotton gloves are recommended for operators who will be handling assemblies prior to coating with HumiSeal® 1C55.

Product Specification
Density, per ASTM D1475 0.98 ± 0.02 g/cm³
Min. Solids Content, % by weight per Fed-Std-141, Meth. 4044 99 %
Viscosity, per Fed-Std-141, Meth. 4287 195 -400 centipoise
VOC 0 grams/litre
Recommended Coating Thickness 50 – 200 microns
Recommended Curing Conditions 10 – 15 min @ 105 – 130ºC
Time Required to Reach Optimum Properties 15 min
Recommended Stripper HumiSeal Stripper 1091
Shelf Life at Recommended Conditions, DOM 12 months
Thermal Shock, 50 cycles per MIL-I-46058C -65°C to 200°C
Glass Transition Temperature – DSC < -65ºC
Coefficient of Thermal Expansion – TMA 154 ppm/°C
Modulus – DMA 0.7 MPa @ -40ºC
0.6 MPa @ 25ºC
0.5 MPa @ 80ºC
Tensile 0.15 MPa
Elongation 16%
Dielectric Withstand Voltage, per MIL-I-46058C >1500 volts
Dielectric Breakdown Voltage, per ASTM D149 7000 volts
Dielectric Constant, at 1MHz and 25°C per ASTM D150-98 2.4
Dissipation Factor, at 1MHz and 25°C per ASTM D150-98 0.01
Insulation Resistance, ohms per MIL-I-46058C 5.0 x 1014 (500TΩ)
Moisture Insulation Resistance, ohms per MIL-I-46058C 1.0 x 1010 (10GΩ)
Fungus Resistance, per ASTM G21 Passes

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