Applications

DOWSIL™ 3-4207 Dielectric Tough Gel – Room-temperature curing encapsulant for PCB assemblies needing adhesion, insulation, flame safety

  • Item Name: DOWSIL™ 3-4207 Dielectric Tough Gel

  • Manufacturer: Dow

  • Technologies: Silicone dielectric tough gel

  • Color: Translucent green (blue and yellow parts mix to green, with UV indicator)

  • Cure Type: Fast room temperature cure (heat-accelerated optional)

  • Package Size: 210 mL dual cartridges, 1 gallon pails, 5 gallon pails, 55 gallon drums

  • Shelf Life: 12 months

1. Product Overview

DOWSIL™ 3-4207 is a two-part, translucent green dielectric tough gel formulated for rapid room temperature curing without ovens. It features conditional primerless adhesion, UV inspection capability, and enhanced mechanical strength. The gel provides UL 94 V-1 flame resistance and meets EN45545-2: R25 HL3 railway safety standards, making it highly suitable for transportation and safety-critical electronics. Components are supplied in blue and yellow for mixing accuracy, turning green upon proper blending.


2. Applications

  • Encapsulation of electronic assemblies requiring room temperature curing.

  • High-voltage insulation with stress relief from thermal and mechanical stresses.

  • Railway and transportation electronics requiring EN45545-2 compliance.

  • Moisture and contaminant protection for delicate PCB systems.

  • Optoelectronic devices needing refractive index stability.

  • Reworkable encapsulation where gel removal or repair may be necessary.

3. Typical Properties

Property Unit Result
Still Not Mixed
Viscosity (Part A) cP / mPa·s / Pa·s 425 / 425 / 0.4
Viscosity (Part B) cP / mPa·s / Pa·s 400 / 400 / 0.04
After Mixed / Cured
Cure Time @ 25°C hours 1.5
Gel Time @ 25°C minutes 9.8
Heat Cure Time @ 50°C minutes 10
Heat Cure Time @ 100°C minutes 3
Durometer Shore 00 59
Unprimed Adhesion – 180° Peel Strength ppi / N/cm² 32
Dielectric Strength 450 V/mil (17 kV/mm)
Agency Listing UL 94 V-1
Certification EN45545-2: R25 HL3
Shelf Life @ 25°C months 12

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