Humiseal 1A27 | Polyurethane Conformal Coating

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

Humiseal 1A27 | Polyurethane Conformal Coating

Main features

One-component
Fast-curing
No free isocyanates

Product Description

HumiSeal® 1A27 is a single-component, fast-curing acrylic conformal coating with exceptional dielectric properties and moisture resistance. The coating dries to a tough, transparent, and flexible finish that protects printed circuit board (PCBs) from a wide range of environmental stresses. 1A27 is easy to apply and repair, and it contains a UV fluorescent tracer for inspection and quality control.

The Humiseal 1A27 coating meets the following requirements:

MIL-I-4658C
RoHS Directive 2002/95/EC Compliant
Recognized under UL File Number E105698

Product Key Features

Acrylic Chemistry: Offers a balance of physical, electrical, and moisture-resistant properties.
Fast Curing: The product is tack-free in 10-15 minutes at room temperature, which allows for rapid handling and processing.
Fluorescent Tracer: Contains a UV indicator for easy inspection under a blacklight to ensure complete and uniform coverage.
Resistant to Moisture: Provides a durable barrier against humidity and moisture.

Aplications

Humiseal 1A27 is used for protecting a wide range of electronic assemblies from environmental and mechanical stress. It is suitable for use in industries such as automotive and military electronics, renewable energy, and industrial controls.

Specifications
Additional Information

Technical Specifications

General Properties

Density (g)

0.96 g/cm3

Solids

50 %

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

3000 mPa.s

Electrical Properties

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

3.6

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

0.02

Mechanical Properties

Storage (DMA) Modulus
Storage (DMA) Modulus @ 25°C	18.1 N/mm2

Thermal Properties

Coefficient of Thermal Expansion (CTE)

Coefficient of Thermal Expansion (CTE)
CTE (Coefficient of thermal expansion) is a material property that is indicative of the extent to which a material expands with a change in temperature. This can be a change in length, area or volume, depending on the material.

Knowing the CTE of the layers is helpful in analyzing stresses that might occur when a
system consists of an adhesive plus some other solid component.

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.

170 ppm/°C

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.

28 °C

Operating Temperature

-65 - 125 °C

Curing Conditions

Curing Schedule

Curing Schedule
Curing schedule is the time and temperature required for a mixed material to fully cure. While this applies to materials that cure with heat, there are also other materials that can be cured with UV.

Even though some materials can cure on ambient temperatures, others will require elevated temperature conditions to properly cure.

There are various curing schedules depending on the material type and application. For heat curing, the most common ones are Snap cure, Low temperature cure, Step cure and Staged cure.

Recommended cure type, schedule, time and temperature can always be found on the Technical data sheets.

Full Cure Time

30 hours

Additional Information

Frequently Asked Questions About HumiSeal® 1A27

What are typical applications for HumiSeal® 1A27?

HumiSeal® 1A27 is a one-part, polyurethane conformal coating designed to protect printed circuit board assemblies (PCBs) in demanding environments. Its excellent moisture and chemical resistance, along with its wide operating temperature range, make it a reliable choice for a variety of industries, including:

Military and aerospace electronics (e.g., control modules, avionics)
Industrial electronics (e.g., motor drives, sensors, process controls)
Automotive electronics (e.g., electronic control units)
Instrumentation and monitoring equipment

This coating is particularly well-suited for applications where reliable environmental protection is required and where a fast-drying, solvent-based system is preferred.

Why choose HumiSeal® 1A27 over other conformal coatings?

HumiSeal® 1A27 is a single-component, high-performance polyurethane formulation that is fast-drying. It provides excellent chemical and moisture resistance. Unlike coatings that require specialized curing equipment, 1A27 cures simply by reacting with solvent evaporation, making it a cost-effective and easy-to-implement solution. It is a flexible coating with high abrasion resistance, and its viscosity is optimized for spray, brush, or dip application. The coating is compliant with MIL-I-46058C, and it meets the requirements of the RoHS Directive 2002/95/EC and is recognized under UL File Number E105698. You can learn how to select a conformal coating in our latest blog.

What is the shelf life of HumiSeal® 1A27?

HumiSeal® 1A27 has a shelf life of 24 months from the date of manufacture when stored at 0 to 35°C in a tightly closed container, away from direct sunlight or excessive heat. As it is a solvent-based material, it is crucial to protect the product from ambient air to prevent premature viscosity increase due to solvent evaporation. Therefore, any open or partial containers should be tightly sealed after use.

How should I clean tools after applying HumiSeal® 1A27?

To flush equipment and clean uncured HumiSeal® 1A27, non-alcohol based solvents like xylene or toluene are suitable. HumiSeal® Thinner 521 is an effective option. For coating removal during rework, the cured film can be difficult to remove. Thermal displacement, mechanical abrasion, and specialized chemical strippers (e.g., HumiSeal® Stripper 1063) are all suitable options for rework.

What happens to HumiSeal® 1A27 after its shelf life?

After the shelf life, the material's viscosity may increase due to solvent evaporation, which can lead to improper application, uneven coating, and a reduction in the protective performance of the cured film. The use of expired material is not recommended as it may compromise the quality and reliability of the coating. Due to its solvent-based nature, proper storage is critical to maintaining product integrity.

How does HumiSeal® 1A27 cure, and why do curing times vary?

HumiSeal® 1A27 is a single-cure, solvent-drying coating that cures by the evaporation of its solvents to form a durable film. The coating has a drying time to handle of 30 minutes and will reach optimum properties within 30 days at room temperature, 30 hours at 76°C, or 20 hours at 88°C. Curing times can vary based on ambient conditions; higher temperature and air flow will accelerate the curing process. Ensuring a well-ventilated and controlled environment is key for a consistent and reliable cure.

What is the recommended thickness for HumiSeal® 1A27?

The recommended coating thickness for HumiSeal® 1A27 is 25 to 75 microns (1-3 mils). This thickness range ensures optimal protective performance while maintaining flexibility and electrical properties. The final thickness can be adjusted based on the application method and specific project requirements.

What are the differences between application methods for HumiSeal® 1A27?

HumiSeal® 1A27 can be applied by dipping, spraying, or brushing. Dipping is often used for high-volume, automated processes, providing uniform coverage for complex geometries. Spraying, using conventional spray equipment, is ideal for selective application and achieving a consistent film. Brushing is suitable for rework or small-scale applications, offering precise control in localized areas. For all methods, ensuring a well-ventilated area is crucial to prevent the build-up of flammable solvent vapors.

What is the maximum operating temperature for HumiSeal® 1A27?

HumiSeal® 1A27 has a continuous use operating temperature range of –65°C to +125°C, providing consistent protection across a wide range of thermal conditions. It is capable of withstanding thermal shock within this range, as demonstrated by its compliance with MIL-I-46058C testing.

What safety precautions should I take when using HumiSeal® 1A27?

HumiSeal® 1A27 contains flammable solvents, so it should be used in well-ventilated areas and kept away from open flames or sparks. Prevent skin and eye contact by wearing appropriate personal protective equipment, including safety glasses and solvent-resistant gloves. Avoid inhalation of vapors and spray mist. Always consult the product's Safety Data Sheet (SDS) for detailed handling, storage, and disposal information.

How can I ensure proper application of HumiSeal® 1A27?

HumiSeal® 1A27 contains a UV fluorescent tracer, which makes it easy to inspect for proper coverage. Under a UV lamp, the coating will fluoresce, allowing visual confirmation of uniform application and film integrity. This feature is essential for quality control and process monitoring, ensuring all required areas of the PCB have been coated uniformly. Test coupons can be used to periodically check thickness and cure quality.

How does HumiSeal® 1A27 perform in harsh environments?

HumiSeal® 1A27 provides excellent protection against moisture, humidity, and chemical exposure. The cured polyurethane film is tough and flexible, ensuring long-term integrity against environmental stressors. This makes it an ideal solution for applications where PCBs are exposed to corrosive agents, moisture, or significant temperature fluctuations, such as in military or industrial settings.

Learn More About HumiSeal® 1A27

HumiSeal® 1A27 is a high-performance, single-component, fast-drying polyurethane conformal coating. Designed for superior protection, this coating offers a simple yet effective solution for safeguarding electronic assemblies in demanding environments. It provides a reliable defense against moisture, chemicals, and temperature extremes, making it an industry staple for protecting PCBs in sectors like military, aerospace, and industrial automation. An added UV fluorescent tracer assists with visual inspection for quality control.

Key Features at a Glance

✔ Single-component, solvent-drying system
✔ Excellent moisture and chemical resistance
✔ Good flexibility and abrasion resistance
✔ Wide operating temperature range
✔ UV fluorescent tracer for inspection
✔ Can be applied by spray, dip, or brush

Simple, Reliable Solvent Cure 🌬️

HumiSeal® 1A27 offers a straightforward and highly reliable curing system that doesn't require any special equipment. It cures at ambient temperature by the evaporation of its solvents. This eliminates the need for ovens or UV lamps, simplifying the production process and reducing energy costs. The tack-free time is just 30 minutes, with optimum properties typically achieved within 30 days at room temperature, depending on atmospheric conditions.

Curing Parameters:

Ambient Cure: Tack-free in 30 minutes. Optimum properties achieved in 30 days at 25°C.
Optional Heat Cure: 30 hours at 76°C or 20 hours at 88°C for accelerated cure.

This simple curing mechanism provides a robust and complete cure for even the most complex PCB assemblies without the need for specialized equipment or process steps.

Application and Compatibility

HumiSeal® 1A27 is a versatile coating formulated for various application methods, making it compatible with a wide range of manufacturing environments.

Compatible With:

✔ Spray, dip, or brush application methods
✔ High-reliability applications requiring excellent moisture resistance
✔ "No-clean" flux residues (users should confirm compatibility)
✔ Lead-free and RoHS-compliant manufacturing environments

Additionally, the coating is reworkable using thermal methods or chemical strippers, making it a practical choice for designs that may require servicing or component repair.

High-Performance Electrical and Physical Protection 🧪

HumiSeal® 1A27 delivers outstanding electrical insulation with a dielectric withstand voltage >1,500 volts and insulation resistance >2.0 × 10¹⁴ ohms. Its polyurethane chemistry provides excellent chemical resistance, flexibility, and abrasion resistance, ensuring long-term durability and protection against moisture, contaminants, and mechanical stress.

Inspection and Quality Control 🔎

HumiSeal® 1A27 contains a UV fluorescent tracer, allowing for easy and reliable inspection under UV light. Quality assurance can be achieved by carefully monitoring the application process to ensure all critical areas are coated to the recommended thickness. This feature is ideal for manufacturers who require a simple, visual method for verifying proper coverage and uniformity across the entire PCB.

Repairable and Reworkable 🔁

Although HumiSeal® 1A27 forms a robust, durable film, it is still reworkable. If component replacement or repair is needed, the cured coating can be selectively removed using thermal displacement (e.g., a soldering iron), mechanical abrasion, or a chemical stripper (e.g., HumiSeal® Stripper 1063). This feature makes 1A27 suitable for applications that require field serviceability or prototype modification.

Reliable Across Environments 🌍

With a continuous operating temperature range of –65°C to +125°C, coupled with excellent moisture and chemical resistance, 1A27 ensures consistent performance across varied environmental conditions. Its robust polyurethane film is particularly well-suited for critical systems exposed to humidity, corrosive agents, and significant temperature cycling.