I347-AT4 Datasheet, PDF (141/148 Pages) Intel Corporation – Intel® Ethernet Network Connection I347-AT4 Datasheet

Thermal Design Recommendations — I347-AT4
Figure 7.3. 10 mm Tall Passive Heat Sink (AAVID Thermalloy PN: 374324B60023G)
7.7.2
Thermal Interface Materials for Heat Sink Solutions
To maximize the effectiveness of any thermal solution, it is important to understand the interface
between the package surface and the heat sink base. The purpose of the Thermal Interface Material
(TIM) is to enhance the heat transfer between two objects in contact (see Figure 7.4). At a microscopic
level, surfaces are often rough and contain many peaks and valleys. They only contact each other at
random points across the interfacing surfaces, thus heat only conducts effectively through those small
points of contact. Heat also conducts through the air in the areas that are not touching; however, air is
a very poor thermal conductor. This results in a high thermal resistance between the two objects.
When a thermal interface material is applied, it fills the remaining gaps between the two surfaces and
provides a much more effective heat path. This enables more heat to conduct through to the heat sink,
reducing the temperature drop across the interface.
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