Humiseal UV40 | Acrylated Urethane Conformal Coating

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

Humiseal UV40 | Acrylated Urethane Conformal Coating

Main features

Acrylated Urethane Conformal Coating
Secondary cure mechanism cures any unexposed areas
Excellent chemical and moisture resistance

Product Description

HumiSeal® UV40 is a single-component, high solids, UV curable, acrylated polyurethane conformal coating designed to provide superior protection for printed circuit board (PCB) assemblies. It boasts excellent chemical resistance, surface hardness, flexibility, and moisture resistance. A key feature is its dual-cure mechanism: it becomes tack-free upon exposure to UV light, and a secondary moisture cure ensures complete curing in shadowed or unexposed areas within 2-3 days at ambient conditions. The coating fluoresces under UV light, making it easier to inspect the coating during and after application.

HumiSeal® UV40 is typically applied using standard selective coating equipment or by conventional hand spray equipment. And brushing can be used for rework or touch-up, it is not the primary application method. The viscosity is formulated for optimal coverage, including sharp edges, and it is a high-solids material, minimizing solvent content. For UV curing, microwave UV ovens equipped with "H" style bulbs are recommended for efficient and complete cross-linking of the UV40.

HumiSeal® UV40 meets rigorous 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, making 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.

Product Family
HS-UV40

1. Select Package Type

5L Can

Catalog Product

Unlike other products we offer, the products listed on this page cannot currently be ordered directly from the website.

Shortest leadtime

Shipping in 6 - 8 weeks

Contact for Pricing

Packaging

TDS, SDS & Technical documents

Specifications
Additional Information

Technical Specifications

General Properties

Density (g)

1.1 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

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 @ 25 ˚C/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

0.01

Mechanical Properties

Storage (DMA) Modulus
Storage (DMA) Modulus @ 25°C	4,280 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.	85 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.	197 ppm/°C

UL 94 Rating

UL 94 Rating
Flammability rating classification.
It determines how fast a material burns or extinguishes once it is ignited.

HB: slow burning on a horizontal specimen; burning rate less than 76 mm/min for thickness less than 3 mm or burning stops before 100 mm
V-2: burning stops within 30 seconds on a vertical specimen; drips of flaming particles are allowed.
V-1: burning stops within 30 seconds on a vertical specimen; drips of particles allowed as long as they are not inflamed.
V-0: burning stops within 10 seconds on a vertical specimen; drips of particles allowed as long as they are not inflamed.
5VB: burning stops within 60 seconds on a vertical specimen; no drips allowed; plaque specimens may develop a hole.
5VA: burning stops within 60 seconds on a vertical specimen; no drips allowed; plaque specimens may not develop a hole

V-0

Additional Information

Frequently Asked Questions About HumiSeal® UV40

What are typical applications for HumiSeal® UV40?

HumiSeal® UV40 is a versatile, high-performance UV curable conformal coating 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 and reliable protection are essential.

Why choose HumiSeal® UV40 over other conformal coatings?

HumiSeal® UV40 is a single-component, high-solids, acrylated polyurethane formulation that provides excellent chemical and environmental resistance. It offers rapid tack-free curing under UV light, significantly accelerating production cycles. A unique secondary moisture cure mechanism ensures full curing of any unexposed "shadow areas" of the coating within 2-3 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 MIL-I-46058C, IPC-CC-830, RoHS Directive 2011/65/EC (and 2015/863/EU), and is UL recognized (UL File Number E105698). UV40 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?

HumiSeal® UV40 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 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?

To flush equipment and clean uncured HumiSeal® UV40, non-alcohol based solvents should be used. HumiSeal® Thinner 521/521EU is recommended. For coating removal during rework, HumiSeal® UV40 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.

What happens to HumiSeal® UV40 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 cure, and why do curing times vary?

HumiSeal® UV40 is a dual-cure coating. The primary cure is achieved rapidly through exposure to UV light, making the coating tack-free almost instantly. The required UV dose ranges from 1.5-3.0 J/cm² (UVA) and irradiance from 0.50-1.15 W/cm², depending on the UV system (arc or microwave, with "H" style bulbs recommended for microwave systems). Heat can also influence UV cure, with higher heat levels allowing for lower UV dose/irradiance. A secondary moisture cure mechanism is designed to fully cure any unexposed "shadow areas" within 2-3 days at ambient conditions. Due to variations in curing equipment and process conditions, it is strongly recommended to consult us for technical support on curing conditions.

What is the recommended thickness for HumiSeal® UV40?

The recommended coating thickness for HumiSeal® UV40 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?

HumiSeal® UV40 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 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?

HumiSeal® UV40 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 135°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?

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, 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?

HumiSeal® UV40 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 perform in harsh environments?

HumiSeal® UV40 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.

Learn More About HumiSeal® UV40

HumiSeal® UV40 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 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%)

Advanced Dual-Cure Technology ⚡

HumiSeal® UV40 leverages a dual-cure system to ensure complete protection. Its primary cure occurs almost instantly under UV light, allowing for immediate handling and significantly boosting production line speed. This makes it ideal for high-volume manufacturing. For areas that UV light cannot reach (known as "shadow areas" under components), a secondary moisture cure mechanism ensures full cross-linking within 2-3 days at ambient conditions. This can be accelerated with mild heat (60-80°C) and humidity for faster full cure.

Curing Parameters:

Primary UV Cure: Tack-free after exposure to UV light (1.5-3.0 J/cm² UVA, 0.50-1.15 W/cm² irradiance, depending on UV system). Microwave UV ovens with "H" style bulbs are recommended.
Secondary Moisture Cure (for shadow areas): 2-3 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.

Application and Compatibility

UV40 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 delivers exceptional electrical insulation with a dielectric withstand voltage >1,500 volts and insulation resistance of 8.0 × 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 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 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 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 and continuous operation up to +135°C, coupled with excellent resistance to fungus (ASTM G21) and moisture, UV40 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.