Thermal Metrology
Thermal and Mechanical Design Guidelines
27
3
Thermal Metrology
This chapter discusses guidelines for testing thermal solutions, including measuring
processor temperatures. In all cases, the thermal engineer must measure power
dissipation and temperature to validate a thermal solution. To define the performance
of a thermal solution the “thermal characterization parameter”,
Ψ
(“psi”) will be used.
3.1
Characterizing Cooling Performance
Requirements
The idea of a “thermal characterization parameter”,
Ψ
(“psi”), is a convenient way to
characterize the performance needed for the thermal solution and to compare thermal
solutions in identical situations (same heat source and local ambient conditions). The
thermal characterization parameter is calculated using total package power.
Note:
Heat transfer is a three-dimensional phenomenon that can rarely be accurately and
easily modeled by a single resistance parameter like
Ψ
.
The case-to-local ambient thermal characterization parameter value (
Ψ
CA
) is used as a
measure of the thermal performance of the overall thermal solution that is attached to
the processor package. It is defined by the following equation, and measured in units
of °C/W:
Ψ
CA
= (T
C
– T
A
) / P
D
(Equation
1)
Where:
Ψ
CA
= Case-to-local ambient thermal characterization parameter (°C/W)
T
C
= Processor case temperature (°C)
T
A
= Local ambient temperature in chassis at processor (°C)
P
D
= Processor total power dissipation (W) (assumes all power dissipates
through the IHS)
The case-to-local ambient thermal characterization parameter of the processor,
Ψ
CA
, is
comprised of
Ψ
CS
, the thermal interface material thermal characterization parameter,
and of
Ψ
SA
, the sink-to-local ambient thermal characterization parameter:
Ψ
CA
=
Ψ
CS
+
Ψ
SA
(Equation 2)
Where:
Ψ
CS
= Thermal characterization parameter of the thermal interface material
(°C/W)
Ψ
SA
= Thermal characterization parameter from heatsink-to-local ambient
(°C/W)
Summary of Contents for Celeron Dual-Core E1000 Series
Page 10: ...10 Thermal and Mechanical Design Guidelines...
Page 26: ...Processor Thermal Mechanical Information 26 Thermal and Mechanical Design Guidelines...
Page 68: ...ATX Thermal Mechanical Design Information 68 Thermal and Mechanical Design Guidelines...
Page 86: ...Heatsink Clip Load Metrology 86 Thermal and Mechanical Design Guidelines...
Page 88: ...Thermal Interface Management 88 Thermal and Mechanical Design Guidelines...
Page 120: ...Legacy Fan Speed Control 120 Thermal and Mechanical Design Guidelines...
Page 126: ...Fan Performance for Reference Design 126 Thermal and Mechanical Design Guidelines...
Page 127: ...Fan Performance for Reference Design Thermal and Mechanical Design Guidelines 127...
