EPO-TEK 921-FL
Harmonization Code : 3810.10.00 | Soldering, brazing or welding powders and pastes consisting of metal and other materials
Main features
- Thermally Conductive Electrical Insulation
- Six-Hour Mixed Pot Life
- Adhesive, Seal, and Potting Versatility
Product Description
EPO-TEK 921-FL Thermally Conductive Epoxy is a two-component, high-Tg epoxy that combines thermal conductivity with electrical insulation. The smooth-flowing paste mixes 100:2.2 by weight, has a six-hour pot life, and is the lower-viscosity version of EPO-TEK 921. A recommended cure of one hour at 150 deg C produces a typical bulk thermal conductivity of 1.1 W/(m K) and volume resistivity of at least 6 x 10^13 ohm cm. Supported uses include mounting heat sinks and substrates, sealing electronic packages, and thermal potting.
Key features
- Thermal conduction with electrical insulation: Typical cured values include 1.1 W/(m K) thermal conductivity and volume resistivity of at least 6 x 10^13 ohm cm.
- Controlled mixed-material window: The mixed system provides a six-hour pot life.
- Multiple thermal-management functions: The product supports heat-sink and substrate bonding, package sealing, and thermal potting.
Applications
- Mounting heat sinks and substrates
- Sealing electronic packages
- Thermal potting
TDS, SDS & Technical Documents
Technical Specifications
General Properties
Component System
Two Part
Describes the number of components that must be supplied, mixed, or activated before application or cure.
Physical Properties
Thixotropic index
2.6
Thixotropic Index is a ratio of a material s viscosity at two different speeds in Ambient temperature, generally different by a factor of ten.
A thixotropic material s viscosity will decrease as agitation or pressure is increased. It indicates the capability of a material to hold its shape. Mayonnaise is a great example of this. It holds its shape very well, but when a shear stress is applied, the material easily spreads.
It helps in choosing a material in accordance to the application, dispense method and viscosity of a material.
Viscosity
12,000-20,000 mPa.s
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
Thermal Properties
Glass Transition Temperature (Tg)
≥ 90 °C
The glass transition temperature for organic adhesives is a temperature region where the polymers change from glassy and brittle to soft and rubbery. Increasing the temperature further continues the softening process as the viscosity drops too. Temperatures between the glass transition temperature and below the decomposition point of the adhesive are the best region for bonding.
The glass-transition temperature Tg of a material characterizes the range of temperatures over which this glass transition occurs.
Operating Temperature
< 300 °C
Thermal Conductivity
1.1 W/m.K
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.
Electrical Properties
Volume Resistivity
≥ 6 x 10¹³ Ohms⋅cm
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.
Additional Information
Technical properties
As-supplied / before-processing properties
Typical as-supplied values for the two-component thermally conductive epoxy.
| Property | Value | Unit | Method / condition |
|---|---|---|---|
| Mix ratio by weight | 100:2.2 | - | Part A:Part B |
| Specific gravity | Part A 2.39; Part B 1.02 | - | As supplied |
| Pot life | 6 | h | Mixed system |
| Shelf life - bulk | 6 | months | At room temperature |
| Shelf life - syringe | 6 | months | At -40 deg C |
| Color | Part A grey; Part B amber | - | Before cure |
| Consistency | Smooth flowing paste | - | Before cure |
| Viscosity | 12,000 to 20,000 | cP | At 23 deg C and 10 rpm |
Technical properties
After-processing / final-state properties
Typical cured values describe bulk material or stated test specimens, not complete assembly thermal performance.
| Property | Value | Unit | Method / condition |
|---|---|---|---|
| Recommended cure | 1 | h | At 150 deg C |
| Alternative cure | 5 min at 150 deg C; 10 min at 120 deg C; 20 min at 100 deg C | - | Minimum alternative cures may not achieve all listed properties |
| Glass transition temperature | >= 90 | deg C | Dynamic cure: 20 to 200 deg C; ISO 25 min; ramp -10 to 200 deg C at 20 deg C/min |
| Shore D hardness | 87 | - | Typical cured value |
| Lap shear strength | 1,312 | psi | At 23 deg C |
| Die shear strength | >= 20 kg / 7,112 | psi | At 23 deg C |
| Thermal conductivity | 1.1 | W/(m K) | Typical bulk material value |
| Volume resistivity | >= 6 x 10^13 | ohm cm | At 23 deg C |
| Dielectric constant | 5.94 | - | At 1 kHz |
