Humiseal 1A33 | Urethane Conformal Coating
Harmonization Code : 3909.20.00.90 | Amino-resins, phenolic resins and polyurethanes, in primary forms : Melamine resins : Other
Main features
- Urethane Conformal Coating
- Transparent (UV Fluorescent)
- Low moisture vapor permeability
Product Description
HumiSeal® 1A33 is a single-component, polyurethane conformal coating designed for protection of printed circuit board (PCB) assemblies. It features excellent chemical resistance and moisture protection without containing any free isocyanates, making it safe and environmentally-friendly. The coating fluoresces under UV light, allowing for easy inspection and quality control during and after application.
HumiSeal® 1A33 can be applied by spraying, brushing, or dipping, and its viscosity can be adjusted with compatible thinners (503/521/521EU/600) to ensure uniform coverage, including sharp edges. Optional curing conditions to reach optimum properties is 30 days at RT or 30 hours @ 76°C or 20 hours @ 88°C.
HumiSeal® 1A33 meets rigorous industry standards, including MIL-I-46058C, IPC-CC-830B, IEC 60664-3, UL 746E, UL 94 V-0, and RoHS Directive 2015/863/EU. It is UL recognized (UL File Number E105698) and complies with IEC 61086 and IEC 60068-2-11, making it suitable for demanding applications in military, renewable energy, industrial, automotive, and consumer electronics sectors.
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.
HS-1A33
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TDS, SDS & Technical Documents
- 1A33_HumiSeal_Technical_Data_Sheet
- Humiseal_1A33_English
Technical Specifications
General Properties
Thermal Properties
Electrical Properties
Physical Properties
Additional Information
Frequently Asked Questions About HumiSeal® 1A33
What are typical applications for HumiSeal® 1A33?
HumiSeal® 1A33 is 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)
Its robust chemical resistance and moisture protection make it ideal for harsh environments and mission-critical applications.
Why choose HumiSeal® 1A33 over other conformal coatings?
HumiSeal® 1A33 offers a single-component, urethane-based formulation that provides excellent chemical and environmental resistance without free isocyanates, ensuring safer handling and compliance with environmental regulations. It is compliant with MIL-I-46058C, IPC-CC-830B, RoHS Directive 2015/863/EU, and is UL recognized (UL File Number E105698). The coating fluoresces under UV light to enable easy inspection of coverage, and it can be applied by spraying, brushing, or dipping, offering flexibility for various production processes. Its fast curing with optional heat acceleration allows for efficient manufacturing cycles. You can learn how to select a conformal coating in our latest blog.
What is the shelf life of HumiSeal® 1A33?
HumiSeal® 1A33 has a shelf life of 12 to 24 months from the date of manufacture when stored sealed at room temperature (0 to 35°C). Before use, allow the product to reach room temperature for optimal application performance.
How should I clean tools after applying HumiSeal® 1A33?
Tools such as spray guns, brushes, or dipping tanks used for applying HumiSeal® 1A33 can be cleaned with recommended thinners like HumiSeal® Thinner 503 or 521. For coating removal during rework, use HumiSeal® Stripper 1063. Always ensure proper ventilation and use lint-free cloths during cleaning.
What happens to HumiSeal® 1A33 after its shelf life?
After the shelf life, viscosity and curing characteristics may degrade, potentially leading to uneven coating or reduced protective performance. Use of expired material is not recommended as it may compromise coating quality.
Why do curing times vary for HumiSeal® 1A33?
Curing times depend on ambient temperature and curing method. At room temperature (20–25°C), the coating becomes tack-free in about 15 minutes and fully cures within 20 to 30 hours. Heat curing at 85°C can accelerate full cure to approximately 4 hours, improving production throughput.
What is the recommended thickness for HumiSeal® 1A33?
The recommended coating thickness is 25 to 75 microns to ensure optimal protection without compromising flexibility or electrical performance.
What are the differences between application methods for HumiSeal® 1A33?
HumiSeal® 1A33 can be applied by spraying, brushing, or dipping. Spraying and dipping are preferred for large-scale production to achieve consistent coverage, while brushing is suitable for touch-ups or small batch applications. Viscosity adjustments with thinners 503 or 521 help achieve uniform coatings.
What is the maximum operating temperature for HumiSeal® 1A33?
HumiSeal® 1A33 withstands thermal shock from –65°C to +125°C as per MIL-I-46058C testing. Continuous operation above 125°C is not recommended as it may degrade coating integrity.
What safety precautions should I take when using HumiSeal® 1A33?
Use in well-ventilated areas and avoid open flames due to flammable solvents. Prevent skin and eye contact by wearing appropriate protective equipment. Consult the Safety Data Sheet (SDS) for detailed handling and disposal instructions.
How can I ensure proper application of HumiSeal® 1A33?
The coating fluoresces under UV light, allowing easy inspection of coverage and uniformity, which is critical for high-reliability electronics manufacturing.
How does HumiSeal® 1A33 perform in harsh environments?
HumiSeal® 1A33 provides excellent protection against moisture, chemicals, salt spray, and fungus, maintaining performance in humid, corrosive, and mechanically stressful environments, making it suitable for military, aerospace, automotive, and industrial applications.
Learn More About HumiSeal® 1A33
HumiSeal® 1A33 is a proven solution for engineers seeking long-term protection of electronic assemblies in demanding environments. This urethane conformal coating offers a unique combination of ease of use, excellent electrical insulation, and mechanical resilience—making it an industry favorite for protecting PCBs in sectors such as automotive, aerospace, consumer electronics, and industrial automation.
Key Features at a Glance
- ✔ Compatible with “no-clean” flux residues
- ✔ Cures at room temperature (30 days) or 88°C (20 hrs)
- ✔ Rated UL 94 V-0 for flame retardancy
Versatile Application Methods 🧰
Whether you’re using spraying, dipping, or brushing, 1A33 offers flexibility in manufacturing workflows. It can be diluted with HumiSeal® Thinner 503 to fine-tune application characteristics based on part geometry and production scale. The coating cures at room temperature in 30 hours, or in just 20 hours at 88°C, allowing integration into both batch and inline processes.
Application Methods:
- Spray: 4:1 dilution with HumiSeal® Thinner 521 or 521EU
- Dip: 5–15 cm/min withdrawal rate with HumiSeal® Thinner 503
- Brush: For touch-up applications
Cure the coating at room temperature (30 days) for convenience, or accelerate with thermal curing (20 hrs at 88 °C) to match fast-paced production cycles.
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
- ✔ Cures at room temperature (30 days) or 88°C (20 hrs)
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 🧪
1A33 delivers a dielectric breakdown voltage of 515 volts/mil and an insulation resistance exceeding 2.0 × 10¹⁴ ohms, protecting even the most sensitive circuit designs from moisture, contaminants, and voltage-induced failure. It’s also rated UL 94 V-0, ensuring flame retardancy in critical applications.
Fluorescent for Inspection 💡
To simplify quality assurance, HumiSeal® 1A33 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® 1A33 is easily repairable. Should rework or component replacement be required, the coating can be selectively removed using HumiSeal® Stripper 1063, making it ideal for prototyping, low-volume builds, or field serviceability.
Reliable Across Environments 🌍
With a wide thermal shock range of –65°C to +125°C and resistance to fungus (ASTM G21) and moisture, 1A33 ensures consistent performance across varied environmental conditions. It’s particularly well-suited for mission-critical systems exposed to humidity, mechanical stress, or temperature cycling.
Compliance You Can Trust ✅
HumiSeal® 1A33 meets stringent industry standards, ensuring reliability and regulatory adherence for OEMs and contract manufacturers:
- MIL-I-46058C Qualified
- IPC-CC-830B Compliant
- IEC60664-3 Compliant
- RoHS 2015/863/EU Compliant
- UL Recognized Component (E105698)
- IEC61086 / IEC60068-2-11 Compliant
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