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Processor Thermal/Mechanical Information—Intel
®
Pentium
Dual-Core E2160 Processor
Refer to
implementing a design using T
2.3
Heatsink Design Considerations
To remove the heat from the processor, three basic parameters should be considered:
• The surface area on which the heat transfer takes place. Without any
enhancements, this is the surface of the processor package IHS. One method used
to improve thermal performance is by attaching a heatsink to the IHS. A heatsink
can increase the effective heat transfer surface area by conducting heat out of the
IHS and into the surrounding air through fins attached to the heatsink base.
• The conduction path from the heat source to the heatsink fins. Providing a direct
conduction path from the heat source to the heatsink fins and selecting materials
with higher thermal conductivity typically improves heatsink performance. The
length, thickness, and conductivity of the conduction path from the heat source to
the fins directly impact the thermal performance of the heatsink. In particular, the
quality of the contact between the package IHS and the heatsink base has a higher
impact on the overall thermal solution performance as processor cooling
requirements become stricter. Thermal interface material (TIM) is used to fill in the
gap between the IHS and the bottom surface of the heatsink, and thereby, improve
the overall performance of the stack-up (IHS-TIM-Heatsink). With extremely poor
heatsink interface flatness or roughness, TIM may not adequately fill the gap. The
TIM thermal performance depends on its thermal conductivity as well as the
pressure applied to it. Refer to
on TIM and on bond line management between the IHS and the heatsink base.
• The heat transfer conditions on the surface on which heat transfer takes place.
Convective heat transfer occurs between the airflow and the surface exposed to the
flow. It is characterized by the local ambient temperature of the air, TA and the
local air velocity over the surface. The higher the air velocity over the surface, and
the cooler the air, the more efficient is the resulting cooling. The nature of the
airflow can also enhance heat transfer via convection. Turbulent flow can provide
improvement over laminar flow. In the case of a heatsink, the surface exposed to
the flow includes in particular the fin faces and the heatsink base.
Active heatsinks typically incorporate a fan that helps manage the airflow through the
heatsink.
Passive heatsink solutions require in-depth knowledge of the airflow in the chassis.
Typically, passive heatsinks see lower air speed. These heatsinks are therefore typically
larger (and heavier) than active heatsinks due to the increase in fin surface required to
meet a required performance. As the heatsink fin density (the number of fins in a given
cross-section) increases, the resistance to the airflow increases, and it is more likely
that the air travels around the heatsink instead of through it, unless air bypass is
carefully managed. Using air-ducting techniques to manage the bypass area can be an
effective method for controlling airflow through the heatsink.
2.3.1
Heatsink Size
The size of the heatsink is dictated by height restrictions for installation in a system and
by the real estate available on the motherboard and other considerations for
component height and placement in the area potentially impacted by the processor
heatsink. The height of the heatsink must comply with the requirements and
recommendations published for the motherboard form factor of interest. Designing a
heatsink to the recommendations may preclude using it in system adhering strictly to
the form factor requirements, while still in compliance with the form factor
documentation.
October 2007
Order Number: 315279 -003US
®
Core
Chapter
6.0, Intel® Quiet System Technology (Intel® QST), for details on
CONTROL
®
TM
Intel
Core
TM
2 Duo E6400, E4300, and Intel
and the Thermal Profile.
Section 2.3.4
and
Appendix B
2 Duo E6400, E4300, and Intel
®
for more information
®
®
Pentium
Dual-Core E2160 Processor
TDG
17
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