CoolTherm® SC-324 Thermally Conductive Silicone

Harmonization Code : 3910.00.00.90 | Silicones in Primary Forms; Others

Main features

High thermal conductivity
Durable UL 94 V-0 flame rated, addition-cure PDMS
Low-stress low viscosity potting

Product Description

CoolTherm® SC-324 is a two-component, addition-cure (PDMS) thermally conductive silicone encapsulant for electrical and electronic potting applications that require heat transfer plus silicone compliance. It provides 4.0 W/m·K typical thermal conductivity while maintaining low cure stress, electrical insulation, and environmental resistance. This makes it well-suited for assemblies exposed to vibration, thermal cycling, thermal expansion mismatch, and mechanical shock.

Product Key Features

Thermally Conductive - 4.0 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 - thermal shock resistance and flame retardancy for harsh operating conditions.
UL Rated - UL 94 V-0 certified flame rating.

Applications

After cure, SC-324 forms a compliant silicone elastomer, supporting deep-section potting and assemblies where thermal expansion mismatch and vibration can drive mechanical stress. For dielectric-critical designs, void control is often important to preserve electrical performance.

Power Module Potting: Potting of inverters, converters, and power supplies to provide insulation and environmental protection while supporting heat transfer.
Electric Motors: Encapsulation of windings or stator regions to improve the thermal path from heat-generating components to the housing or cooling structure.

Product Family
PL-SC324

1. Select Package Type

5 Gallon - White

2. Available Color

White

Catalog Product

Unlike other products we offer, the products listed on this page cannot currently be ordered directly from the website.

Shortest leadtime

Shipping in 8 weeks

Contact for Pricing

Packaging

TDS, SDS & Technical documents

Specifications
Additional Information

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.	3.25
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	30000 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.	4.0 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.	10 %
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.	7.4 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.	2.0x10¹³ Ohms⋅cm

Additional Information

Thermally Conductive Silicone Encapsulant

CoolTherm® SC-324

CoolTherm® SC-324 is a two-component, addition-cure (PDMS) silicone encapsulant for electrical and electronic potting where thermal transfer and silicone compliance are both required. It delivers 4.0 W/m·K typical thermal conductivity while retaining silicone advantages such as low cure stress, electrical insulation, and environmental resistance for assemblies exposed to vibration, thermal cycling, and mechanical shock.

4.0 W/m·K (typ.) UL 94 V-0 1:1 mix by weight or volume 30 min working life (25°C)

Technical Data Sheet SDS (Part A) SDS (Part B) Contact Us

Note: Property values shown are typical and not intended for specification. Verify suitability under your geometry, dispense method, and cure profile.

Two-component system (Resin + Hardener)

Key Features

Low stress to help reduce cure-induced stress on sensitive components.
Durable addition-cure PDMS designed not to depolymerize under heat in confined spaces.
Low viscosity relative to many highly thermally conductive potting materials to support wet-out of complex geometries.
Environmental resistance with thermal shock resistance and flame retardancy.
UL 94 V-0 flame rating (per technical data sheet).

Processing Summary

Mix ratio: 1:1 (resin:hardener) by weight or volume. Premix each component prior to combining.

Working life: 30 minutes at 25°C (typ.).

Cure: 24 hours at 25°C or 60 minutes at 125°C, counted after the material reaches target temperature.

Typical Properties

Uncured System Properties (25°C)

Property	SC-324 Resin	SC-324 Hardener	Mixed
Appearance	Pink liquid	White liquid	Light pink liquid
Viscosity (cP) at 25°C	37,000	43,000	30,000
Specific gravity	3.25	3.25	3.25
Working life (minutes) at 25°C	-	-	30

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)	4.0	ISO 22007-2 (Hot Disk transient)
Coefficient of linear thermal expansion (ppm/°C)	105	Per technical data sheet
Hardness (Shore A)	50	ASTM D2240
Tensile strength (MPa)	0.82	ASTM D412
Elongation at break (%)	10	ASTM D412
Moisture absorption (%)	<0.1	ASTM D570
Volume resistivity (ohm-cm) at 25°C	>2 x 10¹³	ASTM D257
Dielectric strength (kV/mm)	7.4	ASTM D149
Dielectric constant at 1 MHz	4.5	ASTM D150
Dissipation factor at 1 MHz	<0.01	ASTM D150
Extractable ionic contaminants (ppm)	<10 each (chloride, sodium, potassium, ammonium, bromide, sulfate)	Per technical data sheet

Storage and handling (per technical data sheet)

Shelf life of each component is six months when stored at 5 to 30°C in the original, unopened container. SC-324 evolves minute quantities of hydrogen gas. Do not repackage or store in unvented containers. Adequately ventilate the work area.

Applications

Where SC-324 Fits

Potting for Battery Packs

Supports heat transfer and environmental protection while maintaining silicone compliance for assemblies exposed to vibration and thermal expansion.

Thermal benchmark: 4.0 W/m·K (typ.).
Flame rating: UL 94 V-0 (per technical data sheet).
Quality lever: Minimize voids for dielectric-critical designs.

Potting for Charging Systems

Low viscosity relative to many highly thermally conductive materials can help wet-out irregular geometries around inductors, transformers, and power components.

Flow benchmark: 30,000 cP mixed viscosity at 25°C (typ.).
Dielectric benchmark: 7.4 kV/mm dielectric strength (typ.).
Compatibility: Avoid cure inhibitors (amines, sulfur, tin salts); patch test if uncertain.

Potting for Electric Motors

Thermally conductive encapsulation can reduce hotspots by improving the thermal path from windings and magnetic components to the cooling structure. Actual temperature reduction depends on geometry, fill quality, and the thermal path.

Electrical benchmark: >2 x 10¹³ ohm-cm volume resistivity at 25°C (typ.).
Moisture benchmark: <0.1% moisture absorption (typ.).
Quality lever: Avoid trapped air to reduce thermal resistance.

Technical Guidance

Tips and Troubleshooting

Issue	Recommended Action
Air bubbles and voids	Premix each component prior to combining, then mix thoroughly at 1:1 ratio. If open mixing is used, consider vacuum degassing for high-voltage or other dielectric-critical assemblies. Dispense to promote air escape where practical and avoid turbulent flow that can re-entrain air.
Incomplete cure	Verify 1:1 mix ratio by weight or volume and ensure homogeneity. Avoid cure inhibitors such as amines, sulfur, or tin salts. Patch test if uncertain. For heat cure, confirm time at temperature after the assembly reaches 125°C.
Thermal or electrical performance below target	Minimize voids. Trapped air increases thermal resistance and can reduce dielectric strength. Confirm full wet-out around components and corners, especially in deep or complex geometries. Control dispense and cure conditions to reduce part-to-part variation.