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- CoolTherm® SC-320 Thermally Conductive Silicone
CoolTherm® SC-320 Thermally Conductive Silicone
- 3.0 W/m·K thermal conductivity
- Low-stress, low-viscosity silicone
- UL 94 V-0 and Class H insulation
Product Description
CoolTherm® SC-320 is a two-component, addition-cure (PDMS) thermally conductive silicone encapsulant designed for electrical and electronic potting applications that require heat transfer, electrical insulation, and silicone compliance in one system. It delivers 3.0 W/m·K typical thermal conductivity while maintaining low cure stress, low viscosity for easier fill, and thermal shock resistance for assemblies exposed to vibration, thermal cycling, and thermal expansion mismatch.
SC-320 is mixed 1:1 by weight or volume, offers 40 minutes working life at 25°C, and can be cured 24 hours at 25°C or 60 minutes at 125°C. It is also UL 94 V-0 rated and approved for use in PDG-H2, Table V insulation constructions (Class H, 180°C).
Product Key Features
- Thermally Conductive - 3.0 W/m·K typical thermal conductivity for improved heat flow through the encapsulant.
- Low Stress - low shrinkage and low cure stress to help reduce stress on sensitive components during cure.
- Durable Addition-Cure Silicone - PDMS chemistry designed not to depolymerize when heated in confined spaces.
- Low Viscosity - supports wet-out and fill of complex geometries compared to many highly thermally conductive potting materials.
- Environmentally Resistant - excellent thermal shock resistance for demanding operating conditions.
- UL Rated - UL 94 V-0 certified and approved for PDG-H2, Table V insulation constructions (Class H, 180°C).
Applications
SC-320 is suited for potting and encapsulating assemblies that require thermal management, electrical insulation, and silicone compliance under thermal cycling and vibration.
- Power Electronics: Potting of converters, inverters, power supplies, and control electronics that require heat transfer plus electrical insulation.
- Charging Systems: Encapsulation of assemblies with irregular geometries where low viscosity supports fill and wet-out.
- Insulation System Applications: Designs requiring UL 94 V-0 flame rating and PDG-H2 Table V, Class H (180°C) insulation system positioning.
Technical Specifications
| General Properties | |
| Appearance Appearance Appearance at room temperature. | Light Pink Liquid |
| Specific Gravity Specific Gravity Specific gravity (SG) is the ratio of the density of a substance to the density of a reference substance; equivalently, it is the ratio of the mass of a substance to the mass of a reference substance for the same given volume. For liquids, the reference substance is almost always water (1), while for gases, it is air (1.18) at room temperature. Specific gravity is unitless. | 3.1 |
| Physical Properties | |
| Viscosity Viscosity Viscosity is a measurement of a fluid’s resistance to flow. Viscosity is commonly measured in centiPoise (cP). One cP is defined as the viscosity of water and all other viscosities are derived from this base. MPa is another common unit with a 1:1 conversion to cP. A product like honey would have a much higher viscosity -around 10,000 cPs- compared to water. As a result, honey would flow much slower out of a tipped glass than water would. The viscosity of a material can be decreased with an increase in temperature in order to better suit an application | 22000 mPa.s |
| Thermal Properties | |
| Thermal Conductivity Thermal Conductivity Thermal conductivity describes the ability of a material to conduct heat. It is required by power packages in order to dissipate heat and maintain stable electrical performance. Thermal conductivity units are [W/(m K)] in the SI system and [Btu/(hr ft °F)] in the Imperial system. | 3.0 W/m.K |
| Mechanical Properties | |
| Elongation Elongation Elongation is the process of lengthening something. It is a percentage that measures the initial, unstressed, length compared to the length of the material right before it breaks. It is commonly referred to as Ultimate Elongation or Tensile Elongation at break. | 15 % |
| Chemical Properties | |
| Moisture absorption | 0.1 % |
| Electrical Properties | |
| Dielectric Strength Dielectric Strength Dielectric strength is measured in kV per mm and is calculated by the Breakdown voltage divided by the thickness of the tested material. Those two properties go hand in hand and while Breakdown voltage is always thickness dependent, dielectric strength is a general material property. As an example, the dielectric strength of Polyimide is 236 kV/mm. If we place 1mm of Polyimide between two electrodes, it will act as an insulator until the voltage between the electrodes reaches 236 kV. At this point it will start acting as a good conductor, causing sparks, potential punctures and current flow. | 7.9 kV/mm |
| 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. | 1.0x1010 Ohms⋅cm |
Additional Information
CoolTherm® SC-320
CoolTherm® SC-320 is a two-component, addition-cure (PDMS) thermally conductive silicone encapsulant for electrical and electronic potting applications that require silicone compliance plus efficient heat transfer. It delivers 3.0 W/m·K typical thermal conductivity while maintaining low cure stress, electrical insulation, and environmental resistance for assemblies exposed to vibration, thermal cycling, and thermal expansion mismatch. It is also approved for use in PDG-H2, Table V insulation constructions (Class H - 180°C).
Note: Property values shown are typical and not intended for specification. Verify suitability under your geometry, dispense method, and cure profile.
Key Features
- Low stress to help reduce cure-induced stress on sensitive components.
- Durable addition-cure PDMS designed not to depolymerize when heated in confined spaces.
- Low viscosity to help wet-out and fill complex geometries more easily than many highly thermally conductive materials.
- Environmental resistance with thermal shock resistance for demanding operating environments.
- UL rated with UL 94 V-0 flame rating and approval for PDG-H2, Table V insulation constructions (Class H - 180°C).
Processing Summary
Uncured System Properties (25°C)
| Property | SC-320 Resin | SC-320 Hardener | Mixed |
|---|---|---|---|
| Appearance | Pink liquid | White liquid | Light pink liquid |
| Viscosity (cP) at 25°C | 25,000 | 20,000 | 22,000 |
| Specific gravity | 3.1 | 3.1 | 3.1 |
| Gel time (minutes) at 121°C | - | - | 2-5 |
| Working life (minutes) at 25°C | - | - | 40 |
Cured Properties (typ.)
Cure basis: 60 minutes at 125°C (time at temperature after the part reaches target temperature).
| Property | Typical value | Test method |
|---|---|---|
| Thermal conductivity (W/m·K) | 3.0 | ISO 22007-2 (Hot Disc transient) |
| Coefficient of linear thermal expansion (ppm/°C) | 110 | ASTM E 831 |
| Hardness (Shore A) | 54 | ASTM D2240 |
| Tensile strength (MPa) | 2.16 | ASTM D412 |
| Elongation at break (%) | 15 | Per technical data sheet |
| Moisture absorption (%) | <0.1 | ASTM D570-81 |
| Volume resistivity (ohm-cm) at 25°C | >1 x 1014 | ASTM D257 |
| Dielectric strength (kV/mm) | 7.9 | ASTM D149 |
| Dielectric constant at 25°C, 1 MHz | 6 | ASTM D150 |
| Dissipation factor at 25°C, 1 MHz | <0.01 | ASTM D150 |
| Extractable ionic contaminants (ppm) | <10 each (chloride, sodium, potassium, ammonium, bromide, sulfate) | Per technical data sheet |
Where CoolTherm SC-320 Fits
CoolTherm SC-320 fits applications where thermally conductive potting and encapsulation are used to pull heat away from cells, windings, and power electronics while also providing electrical insulation and coverage around complex geometries.
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- Compatible with cylindrical, pouch, and prismatic cell formats
- Supports heat management during charge and discharge cycling
- Suitable for customizable battery pack architectures
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- Inverters: Supports thermal dissipation and mechanical cushioning in high voltage, high current operation
- On-board chargers: Provides electrical insulation while helping move heat away from sensitive components
- Converters: Supports efficiency, thermal stability, and long-term performance
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- Helps manage heat around windings and motor components
- Supports higher power density within thermal limits
- Used in potting and encapsulation of e-motor assemblies
CoolTherm SC-320 in Electric Motor Thermal Management
The chart shows how average motor coil temperature rises as torque and output power increase. The three curves compare thermal behavior for an unpotted motor, a motor potted with CoolTherm SC-320, and a motor potted with CoolTherm EP-3500. Across the full operating range, the no-potting condition gives the highest coil temperature, while both potting materials reduce temperature at the same torque. This means potting improves heat transfer away from the windings and helps the motor run cooler under load.
The practical result is improved usable performance. At the same temperature limit, a potted motor can operate at higher torque and higher horsepower than an unpotted one. At the same torque, lower coil temperature also supports better reliability and lower copper losses. Between the two materials shown, CoolTherm SC-320 provides the lowest coil temperature overall, indicating the strongest thermal management benefit.
Tips and Troubleshooting
| Issue | Recommended Action |
|---|---|
| Air bubbles and voids |
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| Incomplete cure |
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| Electrical or thermal performance below target |
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