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CoolTherm™ SC-309 Thermally Conductive Silicone Encapsulant Where to Buy

Product Information

LORD CoolTherm™ SC-309 thermally conductive silicone encapsulant is a two-component system designed to provide excellent thermal conductivity for electrical/electronic encapsulating applications, while retaining desirable properties associated with silicones. CoolTherm SC-309 encapsulant can be either room temperature cured or heat cured for maximum adhesion.

Shelf Life

Shelf life of each component is six months from date of manufacture when stored at 25°C in original, unopened container. The material must be periodically rotated within its container to maintain maximum shelf life. Setting will occur if not mixed.

CoolTherm SC-309 encapsulant evolves minute quantities of hydrogen gas. Do not repackage or store material in unvented containers. Adequately ventilate work area to prevent the accumulation of gas.

Features and Benefits

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 thermal conductive materials.

Environmentally Resistant – provides excellent thermal shock resistance.

UL Rated – provides excellent flame retardancy; UL 94 V-O certified.

Typical Properties*

Mixed Appearance Light Gray Liquid
Mixed Viscosity, cps @ 25°C 3600
Mixed Specific Gravity 1.66
Gel Time, min @ 50°C 5 - 9
Working Life, min @ 25°C 30
Cure Time 24 hr @ 25°C; or
15 min @ 100°C; or
10 min @ 120°C

Cured Typical Properties*

Volume Resistivity, ohm-cm @ 25°C 4.3 x 1013
Thermal Conductivity, W/mK 1.0
Coefficient of Linear Thermal Expansion, ppm/°C 190
Hardness, Shore A 45
Tensile Strength, psi 50
Moisture Absorption, % < 0.5
Dielectric Strength, V/mil 600
Dielectric Constant, @ 25°C 4.0
Dissipation Factor, % @ 25°C 0.004

*Data is typical and not to be used for specification purposes.
Cure schedule of 24 hours at 25°C plus 2 hours at 100°C.


Download Type Name
Download Technical Data Sheet CoolTherm SC-309 Thermally Conductive Silicone Encapsulant
Download Filled Addition-Curing Silicone Encapsulant Handling/Application Notes
Download Selector Guide Electronic Materials for LED Applications