Humiseal 1B66 | Fast-Drying Acrylic Conformal Coating

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

Humiseal 1B66 | Fast-Drying Acrylic Conformal Coating

Main features

One-component
Fast-drying
Excellent moisture & environmental protection

Product Description

HumiSeal® 1B66 is a fast-drying, single-component acrylic conformal coating designed to provide outstanding moisture and environmental protection for printed circuit assemblies. It's known for its excellent flexibility and easy repairability, making it a reliable choice for electronic protection. This product is also compliant with the RoHS Directive 2002/95/EC.

Product Key Features

Fast-drying, single-component formula for quick application and processing.
Provides superior moisture and environmental protection for printed circuit assemblies.
Demonstrates excellent flexibility, helping to prevent cracking from thermal expansion and contraction.
Easily repaired, simplyfying rework and maintenance.
RoHS Directive 2002/95/EC compliant, meeting international environmental standards.

Applications

Printed circuit assemblies.

Specifications
Additional Information

Technical Specifications

General Properties

Density (g)

0.91 g/cm3

Solids

35 %

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

Coefficient of Thermal Expansion (CTE)
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.	175 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.	345 ppm/°C

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.

7500 V

Dissipation Factor
Dissipation Factor @ 25°C /1000 kHz	0.01

Dielectric Constant
Dielectric Constant @ 1000 kHz	2.5

Mechanical Properties

Storage (DMA) Modulus
Storage (DMA) Modulus @ 25°C	850 N/mm2

Additional Information

Frequently Asked Questions About HumiSeal® 1B66

What are typical applications for HumiSeal® 1B66?

HumiSeal® 1B66 is a general-purpose, single-component, fast air drying acrylic 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)
Consumer electronics (e.g., smartphones, gaming devices)

Why choose HumiSeal® 1B66 over other conformal coatings?

HumiSeal® 1B66 is easy to use and provides excellent protection. It provides excellent electrical insulation, fluoresces under UV for easy inspection, and is easily repairable with HumiSeal® Stripper 1080. It is also compliant with IPC-CC-830 and RoHS Directive 2002/95/EC, making it a trusted choice for demanding applications. You can learn how to select a conformal coating in our latest blog.

What is the shelf life of HumiSeal® 1B66?

HumiSeal® 1B66 has a shelf life of 24 months from the date of manufacture when stored at room temperature (0 to 35°C) in tightly closed containers. Prior to use, allow the product to equilibrate for 24 hours at 18 to 32°C to ensure optimal performance.

How should I clean tools after applying HumiSeal® 1B66?

Tools and equipment used for applying HumiSeal® 1B66 (e.g., spray guns, brushes, or dipping tanks) can be cleaned using HumiSeal® Thinner 503 for dipping & brushing, and HumiSeal® Thinner 521 for spraying. For removing the coating from PCBs during rework, use HumiSeal® Stripper 1080. Always use a lint-free cloth and ensure proper ventilation during cleaning.

What happens to HumiSeal® 1B66 after its shelf life?

Past its 24-month shelf life, HumiSeal® 1B66 may experience changes in viscosity, which could affect application consistency and coating uniformity. Using expired product may lead to suboptimal performance, and the manufacturer will not be liable for quality or performance issues if expired material is used.

Why do curing times vary for HumiSeal® 1B66?

HumiSeal® 1B66 is a fast air-drying coating. Drying times vary depending on temperature, humidity, and film thickness. Typically, the coating will be tack-free in approximately 10 minutes, and fully cured in 24 hours at room temperature, or 30 minutes at 76°C.

What is the recommended thickness for HumiSeal® 1B66?

The recommended coating thickness for HumiSeal® 1B66 is 25 to 75 microns. This range ensures optimal protection without compromising flexibility or electrical performance. The thickness can be adjusted by controlling viscosity with the appropriate thinner during application.

What are the differences between application methods for HumiSeal® 1B66?

HumiSeal® 1B66 can be applied via spraying, dipping, or brushing. Spraying and dipping are ideal for large-scale production, while brushing is suited for small repairs. Each method requires adjusting viscosity with the appropriate thinner for a uniform coating.

What is the maximum operating temperature for HumiSeal® 1B66?

HumiSeal® 1B66 can withstand thermal shock from –65°C to +125°C. It is not recommended for continuous operation above 130°C, as prolonged exposure to higher temperatures may degrade its protective properties.

What safety precautions should I take when using HumiSeal® 1B66?

The solvents in HumiSeal® 1B66 are flammable, so avoid open flames or sparks during application. Use in a well-ventilated area to prevent inhalation of vapors or spray mist, and avoid skin and eye contact. Always consult the Safety Data Sheet (SDS) prior to use for detailed safety guidelines.

How can I ensure proper application of HumiSeal® 1B66?

HumiSeal® 1B66 fluoresces under UV light, allowing for easy inspection of coating coverage. After application, use a UV light source to check for uniform coating and ensure there are no missed areas, which is critical for high-reliability electronics manufacturing.

How does HumiSeal® 1B66 perform in harsh environments?

HumiSeal® 1B66 is designed for harsh conditions, with excellent moisture insulation resistance and fungus resistance per ASTM G21. It maintains performance in humid, mechanically stressful, or temperature-cycling environments, making it ideal for mission-critical systems.

Learn More About HumiSeal® 1B66

HumiSeal® 1B66 is a proven solution for engineers seeking long-term protection of electronic assemblies in demanding environments. This acrylic 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

✔ Tack-free in 10 minutes at room temperature
✔ Compatible with “no-clean” flux residues
✔ Low viscosity for easy application

Versatile Application Methods 🧰

Application methods

Whether you’re using spraying, dipping, or brushing, 1B66 offers flexibility in manufacturing workflows. It can be diluted with HumiSeal® Thinner 503 or 521 to fine-tune application characteristics based on part geometry and production scale. The coating cures at room temperature in 24 hours, allowing integration into both batch and inline processes.

Application Methods:

Spray: Dilute with HumiSeal® Thinner 521
Dip: 5–15 cm/min withdrawal rate
Brush: For touch-up applications

Cure the coating at room temperature (24 hrs) for convenience, or accelerate with thermal curing 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 (24 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 🧪

1B66 delivers a dielectric breakdown voltage of 7,500 volts and an insulation resistance exceeding 8.0 × 10¹⁴ ohms, protecting even the most sensitive circuit designs from moisture, contaminants, and voltage-induced failure. It is rated for dielectric withstand voltage of >1,500 volts.

Fluorescent for Inspection 💡

To simplify quality assurance, HumiSeal® 1B66 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® 1B66 is easily repairable. Should rework or component replacement be required, the coating can be selectively removed using HumiSeal® Stripper 1080, 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, 1B66 ensures consistent performance across varied environmental conditions. It’s particularly well-suited for mission-critical systems exposed to humidity, mechanical stress, or temperature cycling.