Heatsink Size; Heatsink Mass; Package Ihs Flatness - Intel Celeron D Thermal Design Manual

775-land lga package for embedded applications
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2.3.1

Heatsink Size

The size of the heatsink is dictated by height restrictions for installation in a system and by the
space 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.
For the ATX/microATX form factor, it is recommended to use:
The ATX motherboard keep-out footprint definition and height restrictions for enabling
components, defined for the platforms designed with the LGA775 socket in
design guide.
The motherboard primary side height constraints defined in the ATX Specification V2.1 and
the microATX Motherboard Interface Specification V1.1 found at
http://www.formfactors.org/.
For the 1U and 2U server form factor, it is recommended to use:
The 1U and 2U motherboard keep-out footprint definition and height restrictions for enabling
components, defined for the platforms designed with the LGA775 socket in Appendix E of
this design guide. Note that this keep-out footprint is similar to the ATX motherboard
keep-out, with minor differences in the areas surrounding the processor package.
The 1U and 2U primary side constraints defined in the Thin Electronics Bay specification
found at http://www.ssiforum.org/.
The resulting space available above the motherboard is generally not entirely available for the
heatsink. The target height of the heatsink must take into account airflow considerations (for fan
performance for example) as well as other design considerations (air duct, etc.).
2.3.2

Heatsink Mass

With the need for pushing air cooling to better performance, heatsink solutions tend to grow larger
(increase in fin surface) resulting in increased weight. The insertion of highly thermally conductive
materials like copper to increase heatsink thermal conduction performance results in even heavier
solutions. As mentioned in
must take into consideration the package and socket load limits, the heatsink attach mechanical
capabilities, and the mechanical shock and vibration profile targets. Beyond a certain heatsink
weight, the cost of developing and implementing a heatsink attach mechanism that can ensure the
system integrity under the mechanical shock and vibration profile targets may become prohibitive.
The recommended maximum heatsink weight for the Celeron D processor in the 775-land LGA
package is 450g for the ATX form factor. This weight includes the fan and the heatsink only. The
attach mechanism (clip, fasteners, etc.) is not included.
The weight of the heatsinks for server form factors tends to be heavier than desktop form factors
and therefore there isn't a recommended maximum weight. These solutions are sometimes fastened
to the motherboard with the use of a backplate on the secondary side or in some cases are directly
mounted to the server chassis. In all cases, system integrators must ensure that the load
specifications for the package are met during shock and vibration testing.
2.3.3

Package IHS Flatness

The package IHS flatness for the product is specified in the processor datasheet and can be used as
a baseline to predict heatsink performance during the design phase.
®
®
Intel
Celeron
D Processor in the 775-Land LGA Package Thermal Design Guide15
303730
Order #
Processor Thermal/Mechanical Information
Section 2.1, "Mechanical Requirements" on page
Appendix F
of this
9, the heatsink weight

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