HumiSeal 1B31 Acrylic Conformal Coating for PCB Protection

HumiSeal 1B31 Acrylic Conformal Coating Performance

HumiSeal 1B31 is supplied ready for industrial application without a separate catalyst or hardener. The liquid has a typical density of 0.91 ± 0.02 g/cm³, solids content of 35 ± 3% by weight, and viscosity of 200 ± 15 centipoise. It reaches handling dryness in approximately ten minutes under the manufacturer’s reference method, supporting short production cycles and efficient inspection.

The recommended dry coating thickness is 25 to 75 microns. Standard curing conditions are 24 hours at room temperature or 30 minutes at 76°C, while optimum properties develop after approximately seven days. The cured coating remains flexible enough to accommodate vibration and thermal expansion, helping reduce cracking and stress around components and solder joints.

HumiSeal 1B31 Acrylic Conformal Coating for PCB Protection

The coating is developed for printed circuit assemblies requiring a protective barrier against moisture, dirt, surface contamination, and environmental stress. Typical applications include engine-control electronics, in-cabin modules, exterior vehicle devices, military systems, solar and wind-energy controls, industrial automation, instrumentation, LED products, power supplies, household appliances, communication equipment, and sensor assemblies.

HumiSeal 1B31 fluoresces under ultraviolet light, helping operators verify coating presence and coverage during quality inspection. The transparent film also supports visual examination of component markings, solder joints, and board identification. When component replacement or circuit modification is required, the acrylic coating can be removed or locally repaired more easily than many highly cross-linked coating chemistries.

7 Benefits of HumiSeal 1B31 Acrylic Conformal Coating

• Fast drying: Reaches handling dryness in approximately ten minutes under reference conditions.
• One-component processing: Requires no weighing, mixing, or separate curing agent.
• Moisture protection: Shields circuit assemblies from humidity, dirt, and environmental contamination.
• Flexible cured film: Accommodates thermal expansion, vibration, and normal mechanical stress.
• UV inspection: Fluoresces under ultraviolet light to simplify coating-coverage verification.
• Easy repairability: Supports localized removal, component replacement, and PCB rework.
• Industry compliance: Meets MIL-I-46058C, IPC-CC-830, and IEC 61086 requirements and complies with REACH and RoHS EU 2015/863.

Applying HumiSeal 1B31 Acrylic Conformal Coating

Printed circuit boards should be clean and dry before coating. Remove oil, dust, moisture, fingerprints, flux residue, and other contamination that may affect wetting or adhesion. The product may also be used on assemblies manufactured with qualified low-residue no-clean processes, but compatibility and cleanliness must be verified with representative production boards.

For dip coating, HumiSeal Thinner 503 may be added when needed to obtain a uniform film. HumiSeal recommends a controlled immersion and withdrawal rate of approximately 5 to 15 cm per minute. Tank viscosity should be checked regularly because solvent evaporation can increase viscosity during production.

For spray application, HumiSeal Thinner 521 or 521EU is recommended. A starting coating-to-thinner ratio of 1:1 by volume may be used and then adjusted according to the spray equipment, pressure, board geometry, and required film quality. Brushing is also possible with a small addition of Thinner 503 for localized protection, prototypes, maintenance, and PCB repair.

HumiSeal 1B31 Acrylic Conformal Coating Electrical Properties

The cured coating is self-extinguishing under the referenced MIL test method and withstands 50 thermal-shock cycles from -65°C to 125°C. Published electrical properties include dielectric withstand voltage above 1,500 volts, dielectric breakdown voltage of approximately 7,500 volts, dielectric constant of 2.5 at 1 MHz and 25°C, and insulation resistance of approximately 8.0 × 10¹⁴ ohms. The cured coating also passes the ASTM G21 fungus-resistance test.

Finished-board performance depends on coating thickness, surface cleanliness, edge coverage, component geometry, curing conditions, voltage spacing, humidity, contamination, and service temperature. Users should validate adhesion, insulation resistance, thermal cycling, humidity exposure, flammability, and rework procedures on the completed electronic assembly.

Storage, Safety, and Official Product Resources

Store HumiSeal 1B31 in tightly closed containers away from excessive heat or cold. The manufacturer lists a storage temperature range of 0°C to 35°C and a shelf life of 24 months from the date of manufacture. Before application, allow the product to equilibrate for 24 hours at a room temperature between 18°C and 32°C.

The solvent-based coating is flammable. Application areas require suitable ventilation, control of flames and ignition sources, appropriate personal protective equipment, and review of the current safety data sheet before handling. Do not return used or contaminated coating to the original container.

Review the official HumiSeal 1B31 product page and the official HumiSeal 1B31 technical data sheet for current specifications, application instructions, certifications, safety information, and storage guidance.

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