COOLTHERM EP-340
Harmonization Code : 3910.00.00.90 | Silicones in Primary Forms; Others

Main features
- 1.5 W/(m K) Thermal Interface
- 7,000 to 60,000 cP Mixed Viscosity
- Low Cured Coefficient of Linear Thermal Expansion
Product Description
CoolTherm® EP-340 Epoxy Resin is a black, filled epoxy resin formulated for use with Thermoset® Hardener No. 18, No. 67, or No. 70. The selected hardener determines the mixed viscosity, working life, cure schedule, operating-temperature capability, and cured mechanical and electrical properties. The resin has a typical viscosity of 300,000 cP at 25 °C and forms thermally conductive encapsulation systems with a typical cured thermal conductivity of 1.5 W/m·K by ISO 22007-2. Its low coefficient of thermal expansion supports applications where expansion and contraction of the cured epoxy encapsulation must be controlled.
Key features
- Configurable epoxy system: Compatible with three documented Thermoset hardeners for room-temperature cure, elevated-temperature cure, or lower-viscosity processing.
- Thermally conductive encapsulation: Each documented cured system provides a typical thermal conductivity of 1.5 W/m·K using the Hot Disc Transient Method, ISO 22007-2.
- Controlled thermal expansion: Cured-system coefficients of linear thermal expansion range from 28 to 31 ppm/°C, depending on the selected hardener.
Applications / Suitable for
- Thermally conductive epoxy potting and encapsulation
- Encapsulation systems requiring controlled expansion and contraction
- Automated meter/mix/dispense processing in high-volume production
TDS, SDS & Technical Documents
Technical Specifications
General Properties
Physical Properties
Additional Information
As-supplied / before-processing properties
Typical resin and mixed-system properties before cure. Values for mix ratio, viscosity, working life, and cure schedule depend on the selected Thermoset hardener and are not intended for specification purposes.
| Property | Value | Unit | Method / condition |
|---|---|---|---|
| Appearance | Black liquid | — | CoolTherm EP-340 resin as supplied |
| Viscosity | 300,000 | cP | Resin at 25 °C; test method not stated |
| Specific gravity | 2.4 | — | Resin; test temperature and method not stated |
| Mix ratio by weight | 100:3.5 / 100:6.0 / 100:7.0 | Resin:hardener | Thermoset Hardener No. 18 / No. 67 / No. 70 |
| Mix ratio by volume | 100:8.5 / 100:15.5 / 100:16.5 | Resin:hardener | Thermoset Hardener No. 18 / No. 67 / No. 70 |
| Mixed viscosity | 60,000 / 7,000 / 10,000 | cP | At 25 °C; Hardener No. 18 / No. 67 / No. 70 |
| Working life | 40 / 60–120 / 100 | minutes | At 25 °C; Hardener No. 18 / No. 67 / No. 70 |
| Shelf life | 6 | months | Stored at 25 °C in the original, unopened container; periodically rotate container to minimize settling |
After-processing / final-state properties
Typical cured properties for CoolTherm EP-340 systems prepared with Thermoset Hardener No. 18, No. 67, or No. 70. Values are listed in that order and are not intended for specification purposes.
| Property | Value | Unit | Method / condition |
|---|---|---|---|
| Thermal conductivity | 1.5 / 1.5 / 1.5 | W/m·K | Hot Disc Transient Method, ISO 22007-2 |
| Coefficient of linear thermal expansion | 28 / 28 / 31 | ppm/°C | Temperature region and test method not stated |
| Hardness | 92 / 95 / 90 | Shore D | Hardener No. 18 / No. 67 / No. 70 |
| Tensile strength at 25 °C | 43.42 (6,300) / 50.33 (7,300) / 64.81 (9,400) | MPa (psi) | Test method not stated |
| Elongation at break | 2.2 / 2.7 / 4.1 | % | Test method not stated |
| Moisture absorption | 0.10 / 0.08 / 0.17 | % | 24 hours at 25 °C; exposure medium and method not stated |
| Volume resistivity at 25 °C | 2 × 1016 / 5 × 1016 / 6 × 1015 | ohm-cm | Test method not stated |
| Dielectric strength | 16.1 (410) / 16.1 (410) / 16.9 (430) | kV/mm (V/mil) | ASTM D149 |





















