Humiseal 1C55 | Low-Viscosity, Fast Thermal Curing Silicone Conformal Coating

Harmonization Code : 3208.20.90 | Paints and varnishes that are dispersed or dissolved in a non aqueous medium

Humiseal 1C55 | Low-Viscosity, Fast Thermal Curing Silicone Conformal Coating

Main features

VOC-free
Fast thermal curing
Low viscosity

Product Description

HumiSeal® 1C55 is a single component, VOC-free, low viscosity, fast thermal curing silicone conformal coating. The reduced viscosity and long pot life of HumiSeal® 1C55 make it ideal for dipping and spraying. 1C55 has excellent flexibility, contains an optical brightener for inspection under black light and is repairable. HumiSeal® 1C55 coating is RoHS Directive 2011/65/EU compliant.

Product Key Features

Single-component
VOC-free formulation
Low viscosity and long pot life
Fast thermal curing
Excellent flexibility
Repairable
Optical brightener for black light inspection
RoHS Directive 2011/65/EU compliant

Applications

PCB applications with extreme temprature cycling & low outgassing requirements.

Specifications
Additional Information

Technical Specifications

General Properties

Density (g)

0.98 g/cm3

Solids

99 %

Thermal Properties

Glass Transition Temperature (Tg)

Glass Transition Temperature (Tg)
The glass transition temperature for organic adhesives is a temperature region where the polymers change from glassy and brittle to soft and rubbery. Increasing the temperature further continues the softening process as the viscosity drops too. Temperatures between the glass transition temperature and below the decomposition point of the adhesive are the best region for bonding.

The glass-transition temperature Tg of a material characterizes the range of temperatures over which this glass transition occurs.

-65 °C

Operating Temperature

-65 - 200 °C

Coefficient of Thermal Expansion (CTE)
Coefficient of Thermal Expansion (CTE), α1 Coefficient of Thermal Expansion (CTE), α1 CTE α1 (alpha 1) is the slope of the Coefficient of thermal expansion in a temperature range below the Glass transition temperature (Tg). It explains how much a material will expand until it reaches Tg.	154 ppm/°C

Electrical Properties

Breakdown Voltage

Breakdown Voltage
Breakdown voltage is the minimum voltage necessary to force an insulator to conduct some amount of electricity.
It is the point at which a material ceases to be an insulator and becomes a resistor that conducts electricity at some proportion of the total current.

After dielectric breakdown, the material may or may not behave as an insulator any more because of the molecular structure alteration. The current flow tend to create a localised puncture that totally alters the dielectric properties of the material.

This electrical property is thickness dependent and is the maximum amount of voltage that a dielectric material can withstand before breaking down. The breakdown voltage is calculated by multiplying the dielectric strength of the material times the thickness of the film.

7000 V

Dissipation Factor
Dissipation Factor @ 25°C /1000 kHz	0.01

Dielectric Constant
Dielectric Constant @ 1000 kHz	2.4

Mechanical Properties

Storage (DMA) Modulus
Storage (DMA) Modulus @ 25°C	0.6 N/mm2

Physical Properties

Viscosity

Viscosity
Viscosity is a measurement of a fluid’s resistance to flow.

Viscosity is commonly measured in centiPoise (cP). One cP is defined as
the viscosity of water and all other viscosities are derived from this base. MPa is another common unit with a 1:1 conversion to cP.

A product like honey would have a much higher viscosity -around 10,000 cPs-
compared to water. As a result, honey would flow much slower out of a tipped glass than
water would.

The viscosity of a material can be decreased with an increase in temperature in
order to better suit an application

195 - 400 mPa.s

Additional Information

Frequently Asked Questions About HumiSeal® 1C55

What are typical applications for HumiSeal® 1C55?

HumiSeal® 1C55 is a general-purpose, single-component, fast thermal-curing, low-viscosity silicone conformal coating used for protecting printed circuit board assemblies (PCBs) in various industries. Its low viscosity and long pot life make it ideal for dipping and spraying applications, including the following:

Aerospace systems (e.g., avionics, control modules)
Automotive electronics (e.g., engine control units, sensors)
Industrial automation (e.g., motor drives, PLCs)
Consumer electronics (e.g., smartphones, gaming devices)

Why choose HumiSeal® 1C55 over other conformal coatings?

HumiSeal® 1C55 provides excellent protection, with outstanding flexibility and a VOC-free, solvent-free formulation. It provides excellent electrical insulation, fluoresces under UV for easy inspection, and is easily repairable with HumiSeal® Stripper 1091. It is also compliant with the RoHS Directive 2011/65/EU, making it a trusted choice for demanding applications. You can learn how to select a conformal coating in our blog.

What is the shelf life of HumiSeal® 1C55?

HumiSeal® 1C55 has a shelf life of 12 months from the date of manufacture when stored at or below 27°C in tightly closed containers. Prior to use, allow the product to equilibrate for 24 hours at room temperature to ensure optimal performance. The product also has a long pot life, typically exceeding 30 days.

How should I clean tools after applying HumiSeal® 1C55?

Tools and equipment used for applying HumiSeal® 1C55 (e.g., spray guns, brushes, or dipping tanks) can be cleaned with a suitable solvent, such as a mineral spirit or acetone, before the coating cures. Thinner is not required or recommended for this product. For removing the coating from PCBs during rework, use HumiSeal® Stripper 1091. Always use a lint-free cloth and ensure proper ventilation during cleaning.

What happens to HumiSeal® 1C55 after its shelf life?

Past its 12-month shelf life, HumiSeal® 1C55 may experience changes in viscosity, which could affect application consistency and coating uniformity. Using expired product may lead to suboptimal performance, and the manufacturer will not be liable for quality or performance issues if expired material is used. If the product has cured in the container, it cannot be recovered.

Why do curing times vary for HumiSeal® 1C55?

HumiSeal® 1C55 is a thermal-curing coating. Curing times vary depending on temperature and film thickness. The coating cures quickly under heat, with a tack-free time typically reached within 10–15 minutes at 105–130°C. The full cure is also achieved quickly, with optimum properties reached after just 15 minutes at this temperature range. Using a thermal oven accelerates the process, making it suitable for high-volume production lines.

What is the recommended thickness for HumiSeal® 1C55?

The recommended coating thickness for HumiSeal® 1C55 is 50 to 200 microns. This range ensures optimal protection without compromising flexibility or electrical performance. The thickness is controlled primarily by the application method and withdrawal rate, as the coating is not designed to be thinned.

What are the differences between application methods for HumiSeal® 1C55?

HumiSeal® 1C55 can be applied via spraying, dipping, or brushing. Spraying and dipping are ideal for large-scale production, while brushing is suited for small repairs. This product has a low viscosity and does not require thinning for any of these methods. Each method should be controlled to achieve a uniform coating, especially the withdrawal rate for dipping, which should be between 5–15 cm/min.

What is the maximum operating temperature for HumiSeal® 1C55?

HumiSeal® 1C55 can withstand thermal shock from -65°C to +200°C. It is also rated for continuous operation at 200°C, making it suitable for high-temperature applications where its protective properties must be maintained under constant thermal stress.

What safety precautions should I take when using HumiSeal® 1C55?

HumiSeal® 1C55 is VOC-free and solvent-free, reducing flammability risks. However, proper ventilation is still crucial to prevent inhalation of vapors or spray mist, especially during the curing process. Avoid skin and eye contact. Always consult the Safety Data Sheet (SDS) prior to use for detailed safety guidelines.

How can I ensure proper application of HumiSeal® 1C55?

HumiSeal® 1C55 fluoresces under UV light, allowing for easy inspection of coating coverage. After application, use a UV light source to check for a uniform, void-free coating, which is critical for high-reliability electronics manufacturing.

How does HumiSeal® 1C55 perform in harsh environments?

HumiSeal® 1C55 is designed for harsh conditions, with excellent fungus resistance per ASTM G21 and exceptional moisture insulation resistance. It maintains performance in humid, mechanically stressful, or temperature-cycling environments, making it ideal for mission-critical systems.

Learn More About HumiSeal® 1C55

HumiSeal® 1C55 is a proven solution for long-term protection of electronic assemblies in demanding environments. This silicone conformal coating offers a unique combination of ease of use, excellent electrical insulation, and exceptional flexibility—making it an industry favorite for protecting PCBs in sectors such as automotive, aerospace, consumer electronics, and industrial automation.

Key Features at a Glance

✔ Fast thermal cure, with optimum properties in 15 minutes
✔ Long pot life of >30 days at room temperature
✔ Low viscosity and VOC-free for easy application

Versatile Application Methods 🧰

Application methods

Whether you’re using spraying, dipping, or brushing, 1C55 offers flexibility in manufacturing workflows. It is a 100% solids coating and should not be diluted. The coating cures quickly with heat, allowing for rapid integration into high-volume inline processes.

Application Methods:

Spray: Apply without thinning
Dip: 5–15 cm/min withdrawal rate
Brush: For touch-up applications

The quick thermal cure (10–15 min at 105–130°C) allows for high-speed production, while its long pot life ensures stability for dipping applications over extended periods.

Application Compatibility

It integrates well with lead-free processes, supports standard cleaning practices, and offers strong performance even on flux-contaminated surfaces.

Compatible With:

✔ Compatible with “no-clean” flux residues
✔ Common PCB finishes including ENIG, HASL, and OSP
✔ High-reliability applications requiring low ionic content
✔ Lead-free and RoHS-compliant manufacturing environments
✔ Fast thermal cure (10–15 min @ 105–130°C)

Additionally, its UV fluorescence ensures easy inspection, and the coating is reworkable using standard HumiSeal strippers—ideal for repairable designs and serviceable assemblies.

High-Performance Electrical Protection 🧪

1C55 delivers a dielectric breakdown voltage of 7,000 volts and an insulation resistance exceeding 5.0×10 14 ohms, protecting even the most sensitive circuit designs from moisture, contaminants, and voltage-induced failure. It is rated for a dielectric withstand voltage of >1,500 volts.

Fluorescent for Inspection 💡

To simplify quality assurance, HumiSeal® 1C55 fluoresces under UV light, making it easy to confirm proper coating coverage during post-application inspection—an essential feature for high-reliability electronics manufacturers.

Repairable and Reworkable 🔁

Unlike many conformal coatings, HumiSeal® 1C55 is easily repairable. Should rework or component replacement be required, the coating can be selectively removed using HumiSeal® Stripper 1091, making it ideal for prototyping, low-volume builds, or field serviceability.

Reliable Across Environments 🌍

With a wide thermal shock range of –65°C to +200°C and resistance to fungus (ASTM G21) and moisture, 1C55 ensures consistent performance across varied environmental conditions. It’s particularly well-suited for mission-critical systems exposed to humidity, mechanical stress, or temperature cycling.