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.
 

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-0 certified.
 

Application:
Mixing – Thoroughly mix each component prior to combining resin and hardener. Mix CoolTherm SC-309 resin with CoolTherm SC-309 hardener at a 1:1 ratio, by weight or volume. Automatic meter/mix/dispense equipment may be used for high volume production. Unless a closed-chamber mechanical mixer is used, air may be introduced into the encapsulant system either during mixing or when catalyzing the mixture. Electrical properties of the silicone encapsulant are best when air bubbles and voids are minimized. Therefore, in extremely high voltage or other critical applications, vacuuming may be appropriate.
Applying – Apply silicone encapsulant using automatic meter/mix/dispense equipment. Avoid applying CoolTherm SC-309 encapsulant to surfaces that contain cure inhibiting ingredients, such as amines, sulfur, or tin salts. If bonding surface is in question, apply a test patch of CoolTherm SC-309 encapsulant to the surface and allow it to set for the normal cure time.
Curing – Allow encapsulant to cure for 24 hours at room temperature (25°C), for 15 minutes at 100°C, or for 10 minutes at 120°C. This time-at-temperature profile refers to the time the material should be allowed to cure once it reaches the target temperature. Allowance should be made for oven ramp rates, parts with large thermal mass and other circumstances that may delay material reaching the target temperature.
 

Shelf Life/Storage:
Shelf life of each component is six months when stored at 5-30°C in original, unopened container. The material must be periodically rotated within its container to maintain maximum shelf life. Settling 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.