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6.4.2
Retention Mechanism Responding in Shock and Vibration
The lead-free process, large package and Integrated Heat Spreader (IHS) application
on the Intel
and vibration comparing with the legacy generation MCH chipset.
The Intel reference thermal solution uses a back plate design that adequately protects
the Solder Ball Joint Reliability (SBJR) of the Intel
data indicates that the back plate design provides measurable improvement in SBJR of
®
the Intel
where processor heatsink is attached to the motherboard. Hence, Intel recommends
using the back plate design on chipset heatsink in such a circumstance to protect the
SBJR.
For customized form factors where the processor heatsink is Direct Chassis Attach
(DCA), customers are recommended to do shock and vibration analysis and test to
determine whether a back plate design is needed or not, which probably will benefit the
customer in controlling the heatsink cost.
6.4.3
Thermal Interface Material
A Thermal Interface Material (TIM) provides improved conductivity between the IHS
and heatsink. The reference thermal solution uses Honeywell PCM45 F*, 0.25mm
(0.010 in.) thick, 20mm x 20mm (0.79 in. x 0.79 in.) square.
Note:
Unflowed or "dry" Honeywell PCM45F has a material thickness of 0.010 inch. The
flowed or "wet" Honeywell PCM45F has a material thickness of ~0.003 inch after it
reaches its phase change temperature.
6.4.3.1
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 PCM45F
TIM is shown in
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
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
inch
/W.
Table 6-1.
Honeywell PCM45F* TIM Performance as a Function of Attach Pressure
Pressure on Psi
38
®
3210 and 3200 Chipset changed the mechanical responses during shock
3210 and 3200 Chipset in ATX form factors (1U ATX-like system is included)
Table
6.1.
2.18
4.35
®
3210 and 3200 Chipset. Analysis
2
/W and End of Life thermal resistance of 0.459 °C
Thermal Resistance (°C x in
End of Line
0.391
0.345
Intel® 3210 and 3200 Chipset Thermal/Mechanical Design Guide
Reference Thermal Solution
®
3210 and 3200
2
)/W
End of Life
0.551
0.459
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