Thermal Metrology For Fc-Pga2 Packaged Processors; Thermal Resistance; Figure 7-1. Processor-Heatsink Thermal Resistance Relationships; Equation 1. Case To Ambient Thermal Resistance - Intel FCPGA2 - Processor - 1 x Pentium 4 2.66 GHz Design Manuallines

R
7. Thermal Metrology for FC-PGA2
Packaged Processors
The following sections will discuss the thermal metrology used on the FC-PGA2 packaged processors.
These techniques should be followed to evaluate thermal performance of proposed solutions. Carefully
read the following instructions and interpretation steps to validate your cooling solution.
7.1.

Thermal Resistance

The thermal resistance value from case to local-ambient (
measure of the cooling solution's thermal performance. Thermal resistance is measured in units of °C/W.
The thermal resistance of the case to local-ambient,
resistance (
strongly dependent on the thermal conductivity and thickness of the TIM between the heatsink and
surface of the processor.
is a measure of the thermal resistance from the bottom of the heatsink cooling solution to the local-
SA
ambient air.
strongly dependent on the air velocity through the fins of the heatsink.

Figure 7-1. Processor-Heatsink Thermal Resistance Relationships

Processor Package
(IHS)
The thermal parameters are related by the following equations:

Equation 1. Case to Ambient Thermal Resistance

249660-001
®
Intel
), and the sink to local-ambient thermal resistance (
CS
is dependent on the heatsink's material, thermal conductivity, and geometry, and is
SA
Heatsink
Thermal Interface
Material
®
Pentium III Processor in the FC-PGA2 Package Thermal Design Guidelines
) for a FC-PGA2 package is used as a
CA
, is comprised of the case-to-sink thermal
CA
Socket
= (T - T ) / TDP
CA CASE LA
) (see Figure 7-1). The
SA
T
ambient
sa
=
ca
T
sink
cs
T
case
value is
CS
+
cs sa
23