Intel Pentium 4 Processor in the 478-Pin Package Thermal Design Guidelines

Intel
®
Pentium
®
4 Processor in the 478-Pin Package Thermal Design Guidelines
R
Design Guide 37
3 Critical to Function Dimensions of
Intel Reference Cooling Solution
3.1 Intel Validation Criteria for the Reference Design
3.1.1 Heatsink Performance
3.1.1.1 Reference Heatsink Performance Target
The Intel reference heatsink is identical for the Intel
®
Pentium
®
4 processor in the 478-pin package
and the Intel
®
Pentium
®
4 processor with 512KB L2 cache on .13 micron process. The reference
heatsink performance targets are given in Table 3. Performance difference is expected when this
heatsink is attached to either processor package: differences in the die size and power density
between both processors changes the heat spreading through the IHS.
Assuming a T
A
at the processor fan heatsink inlet of 45°C, the performance targets given below
support published frequencies for the Intel
Pentium 4 processor in the 478-pin package up to
2GHz, as well as the Intel Pentium 4 processor with 512KB L2 cache on the .13 micron process at
the published frequencies. Refer to the processor datasheet for additional information.
Table 3. Reference Heatsink Performance Target
Processor Thermal Performance, θ
θθ
θca
(Mean + 3σ
σσ
σ)
Details
Intel
®
Pentium
®
4 Processor in
the 478-Pin Package
0.40 °C/W (target) TIM = Chomerics* T454
Nominal clip load = 75 lbf
Intel
®
Pentium
®
4 Processor
with 512KB L2 Cache on .13
Micron Process
0.43 °C/W (target) TIM = Chomerics* T454
Nominal clip load = 75 lbf
3.1.1.2 Altitude
The reference heatsink solutions will be evaluated at sea level. However, many companies design
products that must function reliably at high altitude, typically 1,500 m (5,000 ft) or more. Air-
cooled temperature calculation and measurement at sea level must be adjusted to take into account
altitude effects like variation in air density and overall heat capacity. This often leads to some
degradation in thermal solution performance compared to what is obtained at sea level, with lower
fan performance and higher surface temperatures. The system designer needs to account for this
altitude effects in the overall system thermal design to make sure that the T
C
requirement for the
processor is met at the targeted altitude.