Intel manual Quad-Core Intel Xeon Processor 5400 Series Considerations

Thermal/Mechanical Reference Design

The package includes an integrated heat spreader (IHS). The IHS transfers the non- uniform heat from the die to the top of the IHS, out of which the heat flux is more uniform and spreads over a larger surface area (not the entire IHS area). This allows more efficient heat transfer out of the package to an attached cooling device. The IHS is designed to be the interface for contacting a heatsink. Details can be found in the Quad-Core Intel® Xeon® Processor 5400 Series Datasheet.

The processor connects to the baseboard through a 771-land surface mount socket. A description of the socket can be found in the LGA771 Socket Mechanical Design Guide.

The processor package and socket have mechanical load limits that are specified in the Quad-Core Intel® Xeon® Processor 5400 Series Datasheet and the LGA771 Socket Mechanical Design Guide. These load limits should not be exceeded during heatsink installation, removal, mechanical stress testing, or standard shipping conditions. For example, when a compressive static load is necessary to ensure thermal performance of the Thermal Interface Material (TIM) between the heatsink base and the IHS, it should not exceed the corresponding specification given in the LGA771 Socket Mechanical Design Guide.

The heatsink mass can also add additional dynamic compressive load to the package during a mechanical shock event. Amplification factors due to the impact force during shock must be taken into account in dynamic load calculations. The total combination of dynamic and static compressive load should not then exceed the processor/socket compressive dynamic load specified in the LGA771 Socket Mechanical Design Guide during a vertical shock. It is not recommended to use any portion of the processor substrate as a mechanical reference or load-bearing surface in either static or dynamic compressive load conditions.

2.1.3Quad-Core Intel® Xeon® Processor 5400 Series Considerations

An attachment mechanism must be designed to support the heatsink since there are no features on the LGA771 socket to directly attach a heatsink. In addition to holding the heatsink in place on top of the IHS, this mechanism plays a significant role in the robustness of the system in which it is implemented, in particular:

•Ensuring thermal performance of the TIM applied between the IHS and the heatsink. TIMs, especially ones based on phase change materials, are very sensitive to applied pressure: the higher the pressure, the better the initial performance. TIMs such as thermal greases are not as sensitive to applied pressure. Refer to Section 2.5.2 and Section 2.5.7.2 for information on tradeoffs made with TIM selection. Designs should consider possible decrease in applied pressure over time due to potential structural relaxation in enabled components.

•Ensuring system electrical, thermal, and structural integrity under shock and vibration events. The mechanical requirements of the attach mechanism depend on the weight of the heatsink and the level of shock and vibration that the system must support. The overall structural design of the baseboard and system must be considered when designing the heatsink attach mechanism. Their design should provide a means for protecting LGA771 socket solder joints as well as preventing package pullout from the socket.

Note: The load applied by the attachment mechanism must comply with the package and socket specifications, along with the dynamic load added by the mechanical shock and vibration requirements, as identified in Section 2.1.1.

18 Quad-Core Intel® Xeon® Processor 5400 Series TMDG