Humiseal 1B51NS | One-Component Synthetic Rubber Conformal Coating

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

Humiseal 1B51NS | Fast-Drying Synthetic Rubber Conformal Coating

Main features

Fast-drying formula
Low moisture vapor permeability
Flexible & low stress

Product Description

HumiSeal® 1B51NS is a fast-drying, single-component, synthetic rubber conformal coating. It's formulated with methylcyclohexane solvent, making it a more environmentally friendly option than traditional solvents. Due to its unique base polymer, this coating offers extremely low moisture vapor permeability, excellent flexibility, and low stress on components. 1B51NS is also easy to repair and fully compliant with the RoHS Directive 2002/95/EC.

Product Key Features

Fast-drying & single-component
Uses methylcyclohexane, a more environmentally responsible alternative.
Low moisture permeability
Flexible & low stress
Allows for simple touch-ups or rework as needed.
RoHS Compliant: Meets strict European environmental standards for restricted hazardous substances.

Applications

Suitable printed circuit assemblies.

Specifications
Additional Information

Technical Specifications

General Properties

Density (g)

0.81 g/cm3

Solids

22 %

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.

4900 V

Dielectric Constant

Dielectric Constant
Dielectric Constant (k), commonly known as relative permittivity, is a number relating the ability of a material to carry alternating current to the ability of vacuum to carry alternating current.

It determines the ability of an insulator to store electrical energy and is the ratio of electric permeability in vacuum against the electric permeability of a material.

The lower the dielectric constant (κ) and dissipation factor, the less energy is absorbed from an electric field, making it a much better insulator.

It is a dimensionless property that can be affected by various factors such as the thickness uniformity of a material, insufficient contact between the sample and electrodes, water adsorption and contact resistance.

Dielectric Constant @ 1000 kHz

2.5

Dissipation Factor

Dissipation Factor
Dissipation factor is commonly known as loss tangent or tan delta.

It is a ratio of the loss index and the relative permittivity and it measures the inefficiency of an insulating material to maintain energy (that otherwise dissipates in the form of heat). The lower the factor, the better the insulation.

It is the reciprocal of the quality factor and always refers to a specific temperature and frequency.

Dissipation Factor @ 25°C /1000 kHz

0.07

Mechanical Properties

Storage (DMA) Modulus
Storage (DMA) Modulus @ 25°C	35.3 N/mm2

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.

14 °C

Operating Temperature

-65 - 125 °C

Additional Information

Frequently Asked Questions About HumiSeal® 1B51NS

What are typical applications for HumiSeal® 1B51NS?

HumiSeal® 1B51NS is a single-component, moisture-curing polyurethane conformal coating used for protecting printed circuit board assemblies (PCBs) in various industries, including:

Aerospace systems (e.g., avionics, control modules)
Automotive electronics (e.g., engine control units, sensors)
Industrial automation (e.g., motor drives, PLCs)
Marine electronics (e.g., navigational equipment)

Why choose HumiSeal® 1B51NS over other conformal coatings?

HumiSeal® 1B51NS offers excellent flexibility, superior moisture resistance, and great adhesion. As a polyurethane, it provides a tough, chemical-resistant finish and offers excellent electrical insulation. It also fluoresces under UV light for easy inspection and meets key industry standards such as MIL-I-46058C and RoHS 2002/95/EC.

What is the shelf life of HumiSeal® 1B51NS?

HumiSeal® 1B51NS has a shelf life of 18 months from the date of manufacture when stored at room temperature (18 to 32°C) in a dry place with tightly closed containers.

How should I clean tools after applying HumiSeal® 1B51NS?

Tools and equipment used for applying HumiSeal® 1B51NS can be cleaned with HumiSeal® Thinner 905 or other suitable solvents such as xylene or toluene. For removing the coating from PCBs during rework, use HumiSeal® Stripper 1080 or a similar product. Always use a lint-free cloth and ensure proper ventilation.

What happens to HumiSeal® 1B51NS after its shelf life?

After its 18-month shelf life, HumiSeal® 1B51NS may begin to cure inside the container due to exposure to moisture, leading to a significant increase in viscosity or gelling. Using expired material is not recommended as it may result in poor application and compromised performance. The manufacturer will not be liable for quality issues with expired product.

Why do curing times vary for HumiSeal® 1B51NS?

HumiSeal® 1B51NS cures by reacting with moisture in the air. Therefore, curing times depend heavily on ambient humidity, temperature, and film thickness. Typically, the coating is tack-free in 10 minutes and fully cured in 24 hours at room temperature (25°C) and 50% relative humidity.

What is the recommended thickness for HumiSeal® 1B51NS?

The recommended dry film thickness for HumiSeal® 1B51NS is 25 to 75 microns. Achieving this range ensures optimal protection, especially for electrical insulation and moisture resistance. The viscosity of the coating can be adjusted with HumiSeal® Thinner 905 to achieve the desired thickness for different application methods.

What are the differences between application methods for HumiSeal® 1B51NS?

HumiSeal® 1B51NS can be applied via spraying, dipping, or brushing. Spraying and dipping are ideal for high-volume, uniform coverage, while brushing is suitable for small repairs or touch-ups. Each method requires careful control of viscosity and film thickness to ensure a consistent, defect-free coating.

What is the maximum operating temperature for HumiSeal® 1B51NS?

HumiSeal® 1B51NS has a thermal shock resistance from -65°C to +125°C. The coating is not recommended for continuous operation above 125°C, as prolonged exposure to higher temperatures can degrade its protective properties.

What safety precautions should I take when using HumiSeal® 1B51NS?

HumiSeal® 1B51NS contains flammable solvents, so it should be used in a well-ventilated area, away from open flames or sparks. Proper personal protective equipment (PPE) such as gloves, eye protection, and a respirator are recommended to prevent skin contact and vapor inhalation. Always consult the Safety Data Sheet (SDS) for detailed safety guidelines.

How can I ensure proper application of HumiSeal® 1B51NS?

HumiSeal® 1B51NS contains a UV tracer that causes it to fluoresce under UV light. This feature allows for quick and easy inspection of the coating to ensure uniform coverage and detect any missed areas, which is crucial for maintaining the integrity of the circuit board.

How does HumiSeal® 1B51NS perform in harsh environments?

HumiSeal® 1B51NS provides excellent protection against moisture, humidity, and contaminants. Its durable synthetic rubber composition creates a barrier that guards against electrical leakage and corrosion, making it suitable for demanding applications exposed to harsh environmental conditions.

Learn More About HumiSeal® 1B51NS

HumiSeal® 1B51NS is a reliable solution for engineers and manufacturers seeking long-term protection of electronic assemblies. This single-component polyurethane conformal coating cures with moisture from the air, offering a combination of ease of application, superior moisture resistance, and electrical insulation. Its toughness and chemical resistance make it a trusted choice for protecting PCBs in demanding sectors such as automotive, aerospace, and industrial electronics.

Key Features at a Glance

✔ Cures with moisture from the air
✔ Excellent moisture and chemical resistance
✔ Tough, durable finish

Versatile Application Methods 🧰

Application methods

HumiSeal® 1B51NS offers flexibility in manufacturing workflows. It can be applied via spraying, dipping, or brushing, and its viscosity can be adjusted with HumiSeal® Thinner 521 to achieve optimal application characteristics. The coating cures at room temperature in 24 hours, with curing speed dependent on humidity levels.

Application Methods:

Spray: Dilute with HumiSeal® Thinner 905
Dip: 5–15 cm/min withdrawal rate
Brush: For touch-up applications

Curing is moisture-activated, so controlled humidity environments are recommended for consistent results. Avoid exposure to high humidity before application to prevent premature gelling of the material.

Application Compatibility

It integrates well with various manufacturing processes and provides a robust, long-lasting protective layer. It is compatible with many PCB finishes and is suitable for high-reliability applications requiring low ionic content.

Compatible With:

✔ Most common PCB finishes including ENIG, HASL, and OSP
✔ High-reliability applications requiring a tough coating
✔ Lead-free and RoHS-compliant manufacturing environments
✔ Cures at room temperature with ambient moisture

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

High-Performance Electrical Protection 🧪

1B51NS delivers a dielectric breakdown voltage of 4,900 volts and an insulation resistance of 1.0 x 10¹⁰ ohms, protecting sensitive circuits from moisture, contaminants, and voltage-induced failure. Its robust polyurethane composition ensures a durable and long-lasting barrier.

Fluorescent for Inspection 💡

To simplify quality assurance, HumiSeal® 1B51NS 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 🔁

HumiSeal® 1B51NS can be selectively removed for rework or component replacement using HumiSeal® Stripper 1080 or a similar product, making it ideal for prototyping, low-volume builds, or field serviceability. Its synthetic rubber nature provides a strong, durable film that remains easy to strip when needed.

Reliable Across Environments 🌍

With a wide thermal shock range of –65°C to +125°C and superior resistance to moisture and chemicals, 1B51NS ensures consistent performance across varied environmental conditions. Its durable composition is particularly well-suited for systems exposed to high humidity and mechanical stress.