Humiseal 2C51 | Silicone Conformal Coating

Main features

Fast Room-Temperature Cure
Excellent Electrical Insulation
Visual Quality Control with UV Tracer

Product Description

HumiSeal® 2C51 is a two-component, high-strength silicone encapsulating gel designed to provide excellent protection for printed circuit boards and electronic assemblies. With its low viscosity, it allows for easy application and complete coverage, ensuring thorough encapsulation.

The fast room-temperature cure, combined with a UV tracer for simple inspection, makes HumiSeal® 2C51 ideal for high-reliability electronics. It is RoHS compliant, VOC-free, and offers exceptional dielectric properties, making it well-suited for environments where electrical insulation, shock resistance, and durability are critical.

Target applications

PCB encapsulation/potting of components and connectors
Vibration damping and stress relief around delicate parts (soft gel, Shore 00)
Moisture/environmental protection for control modules and sensors
Gap‑fill around wiring and terminations prior to enclosure close‑out

Specifications
Additional Information

Technical Specifications

General Properties

Density (g)

0.97 g/cm3

Solids

99 %

Mechanical Properties

Hardness Hardness Hardness is a dimensionless quantity. There is no direct relationship between measurements in one scale and their equivalent in another scale or another hardness test.
Durometer (Shore 00)	50

Electrical Properties

Volume Resistivity

Volume Resistivity
Volume resistivity, also called volume resistance, bulk resistance or bulk resistivity is a thickness dependent measurement of the resistivity of a material perpendicular to the plane of the surface.

5.2x10¹⁴ Ohms⋅cm

Thermal Properties

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® 2C51

What are typical applications for HumiSeal® 2C51?

HumiSeal® 2C51 is a low‑viscosity, fast‑gel, two‑component silicone gel used to encapsulate and protect electronic assemblies from moisture, vibration, and electrical stress. It flows to fill gaps around components, cures at room temperature or with mild heat, and includes a UV tracer for inspection.

General PCB encapsulation / potting of components and connectors
Vibration damping and stress relief around delicate parts
Moisture and environmental protection for control modules and sensors

Why choose HumiSeal® 2C51 over alternatives?

1:1 mix by volume/weight for simple processing, very low mixed viscosity for easy dispensing or spray, rapid gel/handle time at room temperature, visual mix confirmation (blue + yellow → green) and built‑in UV tracer for inspection. Electrical properties are robust (UL 94 V‑0, high volume resistivity and dielectric strength) while maintaining a soft Shore 00 45–55 gel for rework and stress relief.

What is the shelf life of HumiSeal® 2C51?

12 months from date of manufacture when stored in tightly closed containers at ≤38 °C. Avoid excessive heat/cold.

How do I clean tools after applying HumiSeal® 2C51?

Use HumiSeal® Stripper 1091 for equipment and tooling clean‑down. Provide adequate ventilation during spray/dispense operations.

What happens after shelf life?

Material may exhibit changes in viscosity, cure speed, or final properties. For critical applications, do not use beyond stated shelf life without re‑qualification.

How do I cure HumiSeal® 2C51?

Mix Part A and Part B 1:1 by volume (or weight) until homogeneous (avoid vigorous mixing to minimize air). Typical cures: 60 min at room temperature to reach optimum properties, or 30 min at 70 °C. Gel time at RT: ~8–10 min. Tack‑free/handle: ~10 min.

What thickness should I apply?

As an encapsulating gel, apply to the desired potting depth needed to fully cover and cushion components (commonly 1–10 mm+ depending on geometry). Ensure cleanliness of the substrate before application.

How is it applied and removed?

Apply by dispensing, brushing, or conventional spraying into dams/molds or directly onto assemblies. For rework, the soft gel can typically be lifted/dug out mechanically; residuals can be softened with an approved stripper and carefully removed.

What temperatures can it withstand?

The TDS does not specify a continuous operating temperature range. As with most silicone gels, suitability across your service temperatures should be validated by testing; consult HumiSeal Technical Support for application‑specific guidance.

Any safety or storage tips?

Use only in well‑ventilated areas. Avoid skin/eye contact. Store away from heat/cold in sealed containers; do not exceed 38 °C. Review the SDS before use.

What are the key material properties?

Appearance: Part A blue, Part B yellow; mixed material turns green with proper mixing; UV tracer for inspection
Rheology: Low viscosity; Part A ~275 cP, Part B ~550 cP (mixed low‑viscosity flow)
Specific gravity: 0.97 ± 0.03 g/cm³
Hardness (Shore 00): 45–55; Gel time (RT): 8–10 min
Electrical: Dielectric strength ~434 V/mil; Volume resistivity ~5.2×10¹³ Ω·cm
Compliance: RoHS (EU 2015/863); UL 94 V‑0
Solids/VOC: ~99% solids; 0 g/L VOC

Is it compatible with metals and coatings?

Silicone gels are broadly compatible with common PCB metals, plastics, and solder masks. Always test for adhesion/compatibility on representative substrates, especially where residues or sensitive finishes are present.

Learn More About HumiSeal® 2C51

HumiSeal® 2C51 is a fast‑curing, two‑part silicone encapsulating gel designed for PCB protection. Its very low viscosity enables excellent flow and void‑free fill, while the 1:1 mix ratio simplifies processing. The mixed material visually confirms blend quality (blue + yellow → green) and incorporates a UV tracer to support post‑fill inspection. The cured gel achieves UL 94 V‑0 flame rating and soft Shore 00 hardness to relieve stress on components and aid rework.

Key Features at a Glance

✔ 1:1 mix (by volume or weight) with rapid room‑temperature gel
✔ Very low viscosity for easy dispensing, brushing, or spraying
✔ Visual color change on mix; built‑in UV tracer for inspection
✔ UL 94 V‑0; high dielectric strength and resistivity
✔ ~99% solids, 0 g/L VOC
✔ Shelf life 12 months; handle in ~10 minutes

Silicone conformal coating for PCB applications

Versatile Application Methods 🧰

Application Methods

HumiSeal® 2C51 can be applied by brushing, spraying, or dipping, offering flexibility for different manufacturing processes. Its low viscosity ensures even coverage and complete encapsulation when needed.

Application Methods:

Brush: For precise or touch-up applications after mixing Parts A and B
Spray: Using conventional spray equipment in a well-ventilated environment
Dip/Pour: Suitable for complete encapsulation of assemblies

Mix Parts A and B in a 1:1 ratio by volume or weight until homogenous, avoiding vigorous mixing to prevent air entrapment.

Curing Options: 30 minutes at 70 °C or 60 minutes at room temperature to achieve full properties.

Application Compatibility

Compatible with a range of PCB materials and component types when surfaces are properly prepared:

PCB assemblies and modules
Shock/vibration-sensitive components
Areas requiring high dielectric insulation

UV tracer allows quick, accurate inspection under UV light to verify full coverage before assembly.

High-Performance Electrical Protection 🧪

2C51 delivers a dielectric strength of 434 V/mil and an insulation resistance exceeding 5.5 × 10¹³ 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.

Inspection Made Easy 💡

To simplify quality assurance, HumiSeal® 2C51 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 🔁

The soft Shore 00 gel can be mechanically lifted for access to components. Any residues can be softened with an approved stripper and removed carefully.