Humiseal UV40 LED | LED UV Curable Conformal Coating

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

Humiseal UV40 LED | LED UV Curable Conformal Coating

Main features

Tack free cure with LED UV light
Excellent chemical and moisture resistance
Dual-cure mechanism

Product Description

HumiSeal® UV40 LED is a cutting-edge, single-component, high-solids, UV LED curable, acrylated polyurethane conformal coating that delivers reliable protection for printed circuit board (PCB) assemblies. This advanced formulation exhibits chemical resistance, surface hardness, flexibility, and moisture resistance. A key feature is its dual-cure mechanism: it achieves a tack-free state upon exposure to UV LED light, while a secondary moisture cure ensures complete curing in shadowed or unexposed areas within 7 days at ambient conditions. For enhanced quality control, the coating fluoresces under UV light, simplifying inspection during and after application.

HumiSeal® UV40 LED is designed for efficient application using selective coating equipment or conventional hand spray equipment, while brushing is recommended for rework or touch-up only. Its optimized viscosity ensures excellent coverage, even over sharp edges, and its high-solids content minimizes solvent use. For UV curing, UV LED curing lamps, specifically those emitting at 385 or 395nm, are recommended for efficient and complete cross-linking of the conformal coating.

HumiSeal® UV40 LED meets stringent industry standards, including MIL-I-46058C and IPC-CC-830. It is recognized under UL File Number E105698 and complies with the RoHS Directive 2011/65/EU and 2015/863/EU, as well as China Standard GB30981-2020. This makes it an ideal choice for demanding applications in sectors such as military, renewable energy (including specialized UV40 SOLAR variants), industrial controls, and automotive and consumer electronics.

Target Applications

General printed circuit board applications
Automotive electronic applications, including in-cabin and exterior use.
Military equipment requiring durable performance.
Renewable energy systems needing robust electronic reliability.
Industrial controls exposed to high humidity, salt-spray, and corrosive environments.

Specifications
Additional Information

Technical Specifications

General Properties

Density (g)

1.05 g/cm3

Solids

95 %

Shelf Life Shelf Life Shelf life is the amount of time after manufacturing that a product is guaranteed to retain its properties. It differs vastly per product and it is based on temperature and storage conditions. The properties can be guaranteed for the temperature and time range indicated on the TDS since those are the ones tested to be the best for the product.
Shelf Life @ 25°C	365 days

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

650 mPa.s

Mechanical Properties

Storage (DMA) Modulus
Storage (DMA) Modulus @ 25°C	29.5 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.	21 ppm/°C
Coefficient of Thermal Expansion (CTE), α2 Coefficient of Thermal Expansion (CTE), α2 CTE α2 (alpha 2) is the slope of the Coefficient of thermal expansion in a temperature range above the Glass transition temperature (Tg). It explains the extent to which a material will expand after it passes Tg.	116 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.

-2.4 °C

Operating Temperature

-65 - 125 °C

Additional Information

Frequently Asked Questions About HumiSeal® UV40 LED

What are typical applications for HumiSeal® UV40 LED?

HumiSeal® UV40 LED is a versatile, high-performance UV curable conformal coating specifically formulated for LED UV curing. It's widely used for protecting printed circuit board assemblies (PCBs) across a broad range of industries, including:

Military and aerospace electronics (e.g., avionics, control modules)
Industrial electronics (e.g., motor drives, sensors)
Automotive electronics (e.g., control units, electronic modules)
Consumer electronics (e.g., communication devices, household electronics)
Solar and photovoltaic systems (UV40-SOLAR variant)
LED displays

Its excellent chemical resistance, surface hardness, flexibility, and moisture resistance make it ideal for harsh environments and mission-critical applications where fast processing, lower energy consumption, and reliable protection are essential.

Why choose HumiSeal® UV40 LED over other conformal coatings?

HumiSeal® UV40 LED is a single-component, high-solids, acrylated polyurethane formulation that provides excellent chemical and environmental resistance. It offers rapid tack-free curing under LED UV light (385nm or 395nm), significantly increasing efficiency of production cycles while benefiting from lower energy consumption, reduced curing temperatures, and no ozone or UV-C generation. Its unique secondary moisture cure mechanism ensures full curing of any unexposed "shadow areas" of the coating within 7 days at ambient conditions (which can be accelerated with heat and humidity). The coating fluoresces under UV light to enable easy inspection of coverage and uniformity. It is compliant with IPC-CC-830, RoHS Directive 2011/65/EC (and 2015/863/EU), and is UL recognized (UL File Number E105698). UV40 LED can be applied by selective coating equipment or conventional hand spray, offering flexibility for various production processes. You can learn how to select a conformal coating in our latest blog.

What is the shelf life of HumiSeal® UV40 LED?

HumiSeal® UV40 LED has a shelf life of 12 months from the date of manufacture when stored sealed in tightly closed opaque containers at 0 to 25°C, away from excessive heat and direct sunlight or full spectrum fluorescent lighting. Before use, allow the product to equilibrate for 24 hours at room temperature for optimal application performance. As UV40 LED is a moisture curing material, care should be taken to protect process vessels and partial containers from moisture by purging with a dry, inert gas (e.g., dry air, nitrogen, or argon) before closure.

How should I clean tools after applying HumiSeal® UV40 LED?

To flush equipment and clean uncured HumiSeal® UV40 LED, non-alcohol based solvents should be used. HumiSeal® Thinner 521/521EU is recommended. For coating removal during rework, HumiSeal® UV40 LED is a highly cross-linked UV cured coating and is more difficult to remove than traditional coatings. Thermal displacement, mechanical abrasion and, where available, HumiSeal® Stripper 1100 are suitable options for rework of HumiSeal® UV40 LED.

What happens to HumiSeal® UV40 LED after its shelf life?

After the shelf life, viscosity and curing characteristics may degrade, potentially leading to uneven coating, reduced protective performance, or improper curing. Use of expired material is not recommended as it may compromise coating quality. Given its photosensitive and moisture-curing nature, proper storage is crucial to maintaining product integrity.

How does HumiSeal® UV40 LED cure, and why do curing times vary?

HumiSeal® UV40 LED is a dual-cure coating. The primary cure is achieved rapidly through exposure to LED UV light (385nm or 395nm), making the coating tack-free almost instantly. The required UV dose and irradiance will depend on the specific LED UV system. A secondary moisture cure mechanism is designed to fully cure any unexposed "shadow areas" within 7 days at ambient conditions. Due to variations in curing equipment and process conditions, it is strongly recommended to consult us for technical support.

What is the recommended thickness for HumiSeal® UV40 LED?

The recommended coating thickness for HumiSeal® UV40 LED is 25 to 125 microns (1-5 mils) to ensure optimal protection without compromising flexibility or electrical performance. The actual thickness will vary based on application equipment and process settings.

What are the differences between application methods for HumiSeal® UV40 LED?

HumiSeal® UV40 LED is best applied by standard selective coating equipment or conventional hand spray equipment for consistent, high-volume application. Brushing is suitable for rework or touch-up only, where the uniformity of the finished coating will depend on component density and operator technique. UV40 LED is generally not suitable for dipping applications. When spraying, the source air must be dry (a dry inert gas is highly recommended) to prevent premature curing of the secondary cure mechanism.

What is the maximum operating temperature for HumiSeal® UV40 LED?

HumiSeal® UV40 LED withstands thermal shock from –65°C to +125°C as per MIL-I-46058C testing. It has a continuous use operating range of -65°C to +125°C. Continuous operation at or above 125°C is generally the upper limit, as prolonged exposure to higher temperatures may degrade coating integrity.

What safety precautions should I take when using HumiSeal® UV40 LED?

Use in well-ventilated areas and avoid inhalation of vapors or spray. Prevent skin and eye contact by wearing appropriate protective equipment, including opaque gloves and UV-protective eyewear specifically designed for LED UV wavelengths, due to its photosensitive nature. The product contains flammable solvents, so avoid open flames or sparks. Consult the Safety Data Sheet (SDS) for detailed handling, storage, and disposal instructions. Ensure that product containers are tightly closed and opaque, and purge partial containers with dry inert gas to prevent premature polymerization.

How can I ensure proper application of HumiSeal® UV40 LED?

HumiSeal® UV40 LED fluoresces brightly under UV light, allowing for quick and easy visual inspection of coating coverage and uniformity. This feature is critical for ensuring proper application and quality control in high-reliability electronics manufacturing, making it simple to identify any missed areas or defects.

How does HumiSeal® UV40 LED perform in harsh environments?

HumiSeal® UV40 LED provides excellent protection against moisture, chemicals, salt spray, and fungus (passes ASTM G21). Its highly cross-linked UV-cured film, combined with the secondary moisture cure, ensures robust performance and maintains integrity in humid, corrosive, and mechanically stressful environments, making it highly suitable for military, aerospace, automotive, and industrial applications. The use of LED UV curing also contributes to reduced energy consumption and minimal emissions, making manufacturing practices safer and more sustainable.

Learn More About HumiSeal® UV40 LED

HumiSeal® UV40 LED is a cutting-edge, single-component, high-solids UV curable conformal coating designed for rapid processing and superior protection of electronic assemblies in demanding environments. This acrylated polyurethane coating offers a unique dual-cure mechanism and a combination of fast processing, excellent chemical resistance, high surface hardness, flexibility, and robust environmental protection—making it an industry leader for protecting PCBs in sectors such as automotive, aerospace, consumer electronics, industrial automation, and even solar applications (with UV40-SOLAR variant).

Key Features at a Glance

✔ Rapid LED UV curing for high throughput
✔ Secondary moisture cure for shadowed areas
✔ Excellent chemical resistance and surface hardness
✔ Fluoresces under UV light for easy inspection
✔ High solids content (>95%)
✔ Lower energy consumption and reduced heat during curing

Advanced Dual-Cure Technology with LED Optimization ⚡

HumiSeal® UV40 LED leverages a dual-cure system to ensure complete protection. Its primary cure occurs almost instantly under LED UV light (385nm or 395nm), allowing for immediate handling and significantly boosting production line speed. This makes it ideal for high-volume manufacturing with added benefits like lower energy usage and reduced heat exposure. For areas that UV light cannot reach (known as "shadow areas" under components), a secondary moisture cure mechanism ensures full cross-linking within 7 days at ambient conditions.

Curing Parameters:

Primary LED UV Cure: Tack-free after exposure to LED UV light (385nm or 395nm). Specific dose and irradiance will depend on the LED UV system.
Secondary Moisture Cure (for shadow areas): 7 days at ambient conditions, or 2-4 hours at 60-80°C with humidity.

This dual-cure capability provides robust and complete protection, even for complex geometries, while optimizing for LED curing technology.

Application and Compatibility

UV40 LED is formulated for efficient application and broad compatibility, fitting seamlessly into modern manufacturing environments.

Compatible With:

✔ Standard selective coating equipment and hand spray methods
✔ High-reliability applications requiring excellent chemical and moisture resistance
✔ "No-clean" flux residues (users should confirm compatibility)
✔ Lead-free and RoHS-compliant manufacturing environments

Additionally, its UV fluorescence ensures easy inspection, and the coating is reworkable using thermal methods or mechanical abrasion—ideal for repairable designs and serviceable assemblies.

High-Performance Electrical and Physical Protection 🧪

HumiSeal® UV40 LED delivers exceptional electrical insulation with a dielectric withstand voltage >1,500 volts and insulation resistance of 5.0 × 10¹⁴ ohms. Its acrylated polyurethane chemistry provides excellent chemical resistance, surface hardness, and flexibility, ensuring durability and protection against moisture, contaminants, and mechanical stress. It's also rated UL 94 V-0 for flame retardancy, ensuring safety in critical applications.

Fluorescent for Inspection 💡

To simplify quality assurance, HumiSeal® UV40 LED fluoresces under UV light, making it easy to confirm proper coating coverage and uniformity during post-application inspection—an essential feature for high-reliability electronics manufacturers seeking efficient and reliable quality control.

Repairable and Reworkable 🔁

While HumiSeal® UV40 LED forms a highly cross-linked, durable film, it is still reworkable. Should component replacement or repair be required, the cured coating can be selectively removed using thermal displacement (e.g., a hot soldering iron), mechanical abrasion, or Humiseal Stripper 1100. This feature makes UV40 LED suitable for applications where field serviceability or prototyping may be necessary.

Reliable Across Environments 🌍

With a wide thermal shock range of –65°C to +125°C, coupled with excellent resistance to fungus (ASTM G21) and moisture, UV40 LED ensures consistent performance across varied environmental conditions. It’s particularly well-suited for mission-critical systems exposed to humidity, corrosive agents, mechanical stress, or extreme temperature cycling. Its compatibility with LED curing systems also contributes to a reduced environmental impact through lower energy consumption.