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CoolTherm® SC-320 Thermally Conductive Silicone
- Low stress
- Durable
- Low viscosity
Product Description
CoolTherm® SC-320 is a high-performance, two-component silicone system engineered for deep-section potting and encapsulation. It delivers excellent thermal conductivity to pull heat away from critical components while maintaining the classic, high-reliability properties of silicones—such as low modulus, high temperature resistance, and exceptional moisture protection. Its flowable consistency ensures complete coverage around intricate geometries, making it a go-to for sensitive electronic assemblies.
Product Key Features
- Low Stress – exhibits low shrinkage and stress on components as it cures.
- Durable – composed of an addition-curing polydimethyl siloxane polymer that will not depolymerize when heated in confined spaces.
- Low Viscosity – maintains low viscosity for ease of component encapsulation compared to other highly thermally conductive materials.
- Environmentally Resistant – provides excellent thermal shock resistance.
- UL Rated – provides excellent flame retardancy; UL 94 V-0 certified; approved for use in PDG-H2, Table V insulation constructions (Class H – 180°C).
Applications
SC-320 is specifically designed for applications where components are subject to thermal cycling and require a stress-relieving protective barrier:
- EV Battery Modules: Potting around battery cells to provide a thermal pathway to cooling plates while absorbing mechanical shock and vibration.
- Power Converters & Inverters: Full encapsulation of high-voltage power electronics to prevent electrical arcing and manage internal heat.
- On-Board Chargers (OBC): Protecting the internal circuitry of vehicle charging systems from environmental contaminants and thermal fatigue.
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: Thermally Conductive Silicone Encapsulant
CoolTherm® SC‑320 is a two‑component, thermally conductive silicone encapsulant engineered for electrical/electronic encapsulating applications. It provides excellent thermal conductivity while retaining the desirable silicone properties of low stress, durability, and environmental resistance.
Low‑stress, durable encapsulation — addition‑cure PDMS chemistry will not depolymerize when heated in confined spaces and exhibits low shrinkage during cure to minimize component stress.
The low‑viscosity formulation aids easy potting and helps reduce voids compared to other highly thermally conductive materials. It offers excellent thermal shock resistance and is UL 94 V‑0 certified; additionally, it is approved for use in PDG‑H2, Table V insulation constructions (Class H – 180 °C).
Encapsulation for thermal management & reliability — designed to protect power electronics, sensors, control modules, and assemblies that require efficient heat transfer with silicone compliance and robust electrical insulation.
For critical and high‑voltage designs, minimizing bubbles/voids preserves dielectric properties and reduces partial discharge risk.
Thermally Conductive • Low Viscosity • Low Stress • UL 94 V‑0 • PDG‑H2 Table V (Class H – 180 °C)
Features & Benefits
- Low Stress — low shrinkage during cure minimizes stress on components.
- Durable — addition‑curing PDMS (won’t depolymerize when heated in confined spaces).
- Low Viscosity — easier encapsulation and improved void reduction.
- Environmentally Resistant — excellent thermal shock resistance.
- UL Rated — UL 94 V‑0; approved for PDG‑H2 Table V insulation (Class H – 180 °C).
Typical Applications
- Potting/encapsulation of power supplies, drivers, and control electronics.
- Encapsulating sensors, PCBs, and heat‑generating modules.
- Assemblies exposed to thermal cycling requiring silicone compliance.
- Designs that demand flame retardancy and strong dielectric performance.
Material Overview
- Appearance (Resin): —
- Chemistry: Addition‑cure silicone (PDMS)
- Flame Rating: UL 94 V‑0; PDG‑H2 Table V (Class H – 180 °C)
- Viscosity @ 25 °C: 22,000 cP
- Specific Gravity: 3.1
- Note: Populate measured values if available.
*Property data are typical and not intended for specification. Verify suitability under your specific process conditions.
Mixing, Applying & Cure
Mixing
Thoroughly premix each component before combining. Mix 1:1 (resin:hardener) by weight or volume. Automatic meter/mix/dispense (MMD) equipment may be used for high‑volume production. If a closed‑chamber mixer is not used, mixing/catalyzing can introduce air.
Applying
Apply via handheld cartridges or automated MMD equipment. Avoid surfaces containing cure‑inhibiting ingredients (amines, sulfur, tin salts). If in doubt, place a test patch and allow to cure for the normal time to confirm compatibility.
Curing
Room‑temperature cure (25 °C) for 24 hours or heat cure 60 minutes at 125 °C. Times refer to time at temperature after the encapsulant reaches setpoint—consider oven ramp rates and large thermal masses that delay soak.
Void Control Note: For extremely high‑voltage or other critical applications, vacuuming is recommended to minimize bubbles and voids, improving dielectric integrity and thermal performance.
Dielectric Integrity & Cure Assurance
Vacuum Degassing
Use vacuum degassing post‑mix (and post‑dispense if necessary) to reduce trapped air that can compromise dielectric strength and raise thermal resistance in high‑reliability builds.
Cure Inhibition Check
Addition‑cure silicones can be inhibited by amines, sulfur, or tin salts. Always verify suspect substrates via a small test patch before full encapsulation.
Standard Packaging & Technical Help
Supplied as a two‑component system (Resin + Hardener) compatible with handheld cartridges or automated MMD equipment. Contact us for guidance on vacuum degassing, cure profiling, and substrate compatibility checks.
Ready to Qualify SC‑320?
Share your potting volume, target dielectric requirements, thermal path constraints, and cure preferences. We’ll help you tune mixing, vacuuming, and cure to achieve reliable performance.