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5.0
Thermal Solution Requirements
5.1
Thermal Solution Characterization
The thermal characterization parameter, Ψ ("psi"), is used to characterize thermal solution
performance, as well as compare thermal solutions in identical situations (i.e., heating source, local
ambient conditions, etc.). It is defined by the following equation:
Equation 1. Junction-to-Local Ambient Thermal Characterization Parameter (Ψ
Ψ
= Junction-to-local ambient thermal characterization parameter (°C/W)
JA
T
= Maximum allowed device temperature (°C)
JUNCTION MAX
T
= Local ambient temperature near the device (°C) (see
A
measurement guidelines)
TDP = Thermal Design Power (W)
The thermal characterization parameter assumes that all package power dissipation is through the
thermal solution (heatsink), and is equal to TDP. A small percentage of the die power (< 5%) is
dissipated through the package/socket/motherboard stack to the environment, and should not be
considered to be a means of thermal control.
The junction-to-local ambient thermal characterization parameter, Ψ
includes the thermal interface material thermal characterization parameter, and of Ψ
local ambient thermal characterization parameter:
Equation 2. Junction-to-Local Ambient Thermal Characterization Parameter
Where:
Ψ
= Thermal characterization parameter from junction-to-sink, this also includes thermal resistance
JS
of the thermal interface material (Ψ
Ψ
= Thermal characterization parameter from sink-to-local ambient (°C/W)
SA
Ψ
is a measure of the thermal characterization parameter from the bottom of the heatsink to the
SA
local ambient air. Ψ
is dependent on the heatsink material, thermal conductivity, and geometry. It is
SA
also strongly dependent on the air velocity through the fins of the heatsink.
combination of the different thermal characterization parameters.
Intel® Core™ 2 Duo Mobile Processors on 45-nm process-Thermal Design Guide
TDG
15
Core™ 2 Duo Mobile Processors—Thermal Solution Requirements
T
Ψ
=
J
JA
TDP
Ψ
= Ψ
JA
JS
) (°C/W).
TIM
−
T
A
Section 7.0, "Thermal Metrology"
, is comprised of Ψ
JA
+ Ψ
SA
Figure 5
Order Number: 320028-001
)
JA
for
, which
JS
, the sink-to-
SA
illustrates the
June 2008
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