COOLTHERM SC-6703
Harmonization Code : 3910.00.00.90 | Silicones in Primary Forms; Others
Main features
- 0.8 W/(m K) Thermal Encapsulation
- 8,000 cP Mixed Viscosity
- 19.7 kV/mm Dielectric Strength
Product Description
CoolTherm® SC-6703 Thermally Conductive Silicone Encapsulant is a two-component silicone system designed for thermally conductive encapsulation of densely packed power units. It is available with black or white resin and uses a white hardener at a 1:1 ratio by weight. The mixed material has a typical 8,000 cP viscosity at 25°C, 1–2 hour working life at 25°C, and 12–14 minute gel time at 66°C. The documented cure is 4 hours at 65°C. Typical cured properties include 0.8 W/m·K thermal conductivity, 60 Shore A hardness, 19.7 kV/mm dielectric strength, and 1 × 1014 ohm-cm volume resistivity.
Key features
- Two-component thermally conductive silicone for densely packed power units
- Black-resin and white-resin variants with a common white hardener
- Simple 1:1 resin-to-hardener ratio by weight
- Low 8,000 cP mixed viscosity for automated meter/mix/dispense processing
- Typical 0.8 W/m·K thermal conductivity and 19.7 kV/mm dielectric strength
- Low-shrinkage, low-stress cured silicone positioning
- Meets UL 94 V-0 requirements, subject to the current listed formulation and construction
Applications
- Thermally conductive encapsulation of densely packed power units
- Electrical and electronic modules requiring flexible silicone insulation
- Critical or extremely high-voltage assemblies using validated vacuum-assisted void control
TDS, SDS & Technical Documents
Technical Specifications
General Properties
Physical Properties
Thermal Properties
Mechanical Properties
Electrical Properties
Additional Information
CoolTherm® SC-6703 Thermally Conductive Silicone Encapsulant
A two-component silicone system developed to provide thermal conductivity and electrical insulation when encapsulating densely packed power units. The platform is available with black or white resin, uses a common white hardener, and supports automatic meter/mix/dispense processing.
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Black and white resin variants with a common hardener
Thoroughly premix each component before combining the selected resin with SC-6703 hardener at 1:1 by weight.
| Property | SC-6703 resin | SC-6703 hardener | Mixed material |
|---|---|---|---|
| Appearance | Black liquid or white liquid | White liquid | Light-grey liquid with black resin; white liquid with white resin |
| Viscosity at 25°C | 15,000 cP | 6,000 cP | 8,000 cP |
| Specific gravity | 2.09 | 1.91 | 2.0 |
| Mix ratio | 1:1 by weight | ||
| Gel time at 66°C | 12–14 minutes | ||
| Working life at 25°C | 1–2 hours | ||
Premix both components, combine 1:1 by weight, minimise air, dispense, and cure
Thoroughly mix each component separately before combining the selected SC-6703 resin with SC-6703 hardener at a 1:1 ratio by weight. Automatic meter/mix/dispense equipment may be used for high-volume production.
- Use a closed-chamber mechanical mixer where practical to reduce introduced air.
- For extremely high-voltage or other critical applications, evaluate vacuum processing to minimise bubbles and voids.
- Apply using automatic meter/mix/dispense equipment.
- Avoid surfaces containing cure-inhibiting amines, sulphur, or tin salts.
- When substrate compatibility is uncertain, apply a test patch and allow the normal cure time.
- Cure for four hours at 65°C after the material reaches the target temperature.
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Storage and industrial handling
Each component has a six-month shelf life when stored at 25°C in its original unopened container. Periodically rotate the material within its container because settling will occur if it is not mixed. Keep containers closed, upright, and in well-ventilated storage. The supplied resin SDS is dated 19 October 2017 and identifies chronic aquatic hazard and a formaldehyde-generation warning for methylpolysiloxanes at approximately 150°C and above in oxygen-containing atmospheres. Confirm current regional resin and hardener SDS documents before publication and use.
Thermal, mechanical, and electrical properties
The following values are typical cured-material results. The supplier reports the cured-property dataset using a 1–2 hour cure at 65°C, while the application section specifies four hours at 65°C for production cure. Final production performance should be validated using the selected cure cycle.
| Property | Typical value | Context |
|---|---|---|
| Thermal conductivity | 0.8 W/m·K | Hot Disc Transient Method, ISO 22007-2. |
| Coefficient of linear thermal expansion | 220 ppm/°C | ASTM C864. |
| Hardness | 60 Shore A | Flexible cured silicone. |
| Tensile strength | 1.38 MPa (200 psi) | ASTM D412 bulk-material property. |
| Elongation at break | 80% | ASTM D412. |
| Volume resistivity at 25°C | 1 × 1014 ohm-cm | ASTM D257; not a finished-assembly working-voltage rating. |
| Dielectric strength | 19.7 kV/mm (500 V/mil) | ASTM D149; breakdown property rather than design working voltage. |
| Dielectric constant | 4.25 at 1 MHz and 25°C | ASTM D150. |
| Dissipation factor | 0.02% at 1 MHz and 25°C | ASTM D150 as published in DS3568. |
Thermal encapsulation for densely packed power units
SC-6703 is directly positioned for densely packed power units requiring heat transfer, electrical insulation, and a flexible silicone encapsulant. Final selection must account for component layout, fill depth, void tolerance, cure inhibition, voltage, creepage and clearance, thermal path, enclosure design, colour requirement, repairability, and environmental exposure.
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Validate SC-6703 for your power-unit encapsulation process
Krayden can help review black or white resin selection, 1:1 weight control, component premixing, automated meter/mix/dispense equipment, vacuum processing, cure inhibition, fill geometry, void control, cure profile, thermal path, electrical insulation, UL scope, and assembly-level qualification for CoolTherm® SC-6703.
