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Intel® 631xESB/632xESB I/O Controller Hub Thermal Mechanical Design Guide 31
Reference Thermal Solution
6.5.2 Extruded Heatsink Profiles
The reference thermal solution uses an extruded heatsink for cooling the chipset MCH.
Figure 6-6 shows the heatsink profile. Appendix A, “Thermal Solution Component
Suppliers” lists a supplier for this extruded heatsink. Other heatsinks with similar
dimensions and increased thermal performance may be available. Full mechanical
drawing of this heatsink is provided in Appendix B, “Mechanical Drawings.”
6.5.3 Mechanical Interface Material
There is no mechanical interface material associated with this reference solution.
6.5.4 Thermal Interface Material
A thermal interface material (TIM) provides improved conductivity between the IHS
and heat sink. The reference thermal solution uses Honeywell PCM45 F, 0.25 mm
(0.010 in.) thick, 25 mm x 25 mm (0.984 in. x 0.984 in.) square.
Note: Unflowed or “dry” Honeywell PCM45 F has a material thickness of 0.010 inch. The
flowed or “wet” Honeywell PCM45 F has a material thickness of ~0.003 inch after it
reaches its phase change temperature.
6.5.4.1 Effect of Pressure on TIM Performance
As mechanical pressure increases on the TIM, the thermal resistance of the TIM
decreases. This phenomenon is due to the decrease of the bond line thickness (BLT).
BLT is the final settled thickness of the thermal interface material after installation of
heatsink. The effect of pressure on the thermal resistance of the Honeywell PCM45 F
TIM is shown in Table 6-1.
Intel provides both End of Line and End of Life TIM thermal resistance values of
Honeywell PCM45F. End of Line and End of Life TIM thermal resistance values are
obtained through measurement on a Test Vehicle similar to Intel 5000 Series chipset’s
physical attributes using an extruded aluminum heatsink. The End of Line value
represents the TIM performance post heatsink assembly while the End of Life value is
the predicted TIM performance when the product and TIM reaches the end of its life.
The heatsink clip provides enough pressure for the TIM to achieve End of Line thermal
resistance of 0.345°C inch
2
/W and End of Life thermal resistance of 0.459°C inch
2
/W.
6.5.5 Heatsink Clip
The reference solution uses a wire clip with hooked ends. The hooks attach to wire
anchors to fasten the clip to the board. See Appendix B, “Mechanical Drawings” for a
mechanical drawing of the clip.
Table 6-1. Honeywell PCM45 F TIM Performance as a Function of Attach Pressure
Pressure on IHS(psi)
Thermal Resistance (°C × in
2
)/W
End of Line End of Life
2.18 0.391 0.551
4.35 0.345 0.459