Technical
Bulletin
Number 211
Electronic Thermal Management Products
eGrafä Anisotropic Thermal Interface Provides Unique Heat
Dissipation
eGraf Thermal Interface Products are the only interface
materials available that provide the unique benefits of anisotropic, or
directional, heat transfer. The thermal
conductivity of eGraf products along the length and width can be up to 200 W/m°C,
approximately 20 to 30 times greater than through the thickness. Because of this anisotropy, eGraf products
dissipate the heat along the entire surface of the heat sink, even in systems
with uneven loading or surface distortion.
The maximum benefit of the heat sink is obtained, and the temperature of
the point source is substantially reduced (Figure B). The end result of using an eGraf anisotropic interface is a
cooler running point source and fewer heat related failures.
eGraf materials are available with through-thickness
conductivity of 7 W/m°C (Class 700) or 12 W/m°C
(Class 1200).
|
Figure A: Heat
Channeling of Conventional Isotropic
Materials |
|
Figure
B: Heat Spreading of Anisotropic eGraf Thermal Interface Products |
|
Simulation
depicts heat transfer from a 5 W source through a conventional interface with
isotropic (equal) conductivity of 7 W/m°C in all
directions. Note the poor dissipation
along the interface, and the high resulting temperature of the source (40°C). This characteristic is typical of
isotropic materials, including “conductor filled” silicone, polyester,
acrylic and thermally conductive greases. |
|
Simulation
depicts heat transfer from a 5 W source through an anisotropic eGraf
interface, with conductivities of 7 W/m°C through
the thickness and 150 W/m°C along the length and width. eGraf Thermal Interface Products spread
heat away from the point source, dramatically reducing the source temperature
(33.5°C) and eliminating hot spots. The heat spreading characteristic enhances
the effective heat transfer area of the heat sink. |
