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PENTIUM® PRO PROCESSOR AT 150, 166, 180, and 200 MHz
higher frequency or otherwise enhanced members of
the Pentium Pro processor family.
6.1.
Thermal Parameters
This section defines the terms used for Pentium Pro
processor thermal analysis.
6.1.1.
AMBIENT TEMPERATURE
Ambient temperature, T
, is the temperature of the
A
ambient air surrounding the package. In a system
environment, ambient temperature is the temperature
of the air upstream from the package and in its close
vicinity; or in an active cooling system, it is the inlet
air to the active cooling device.
6.1.2.
CASE TEMPERATURE
To ensure functionality and reliability, the Pentium
Pro processor is specified for proper operation when
T
(case temperature) is within the specified range in
C
Table 5. Special care is required when measuring the
case temperature to ensure an accurate temperature
measurement. Thermocouples are often used to
measure T
. Before any temperature measurements,
C
the thermocouples must be calibrated. When
measuring the temperature of a surface which is at a
60
different temperature from the surrounding ambient
air, errors could be introduced in the measurements if
not handled properly. The measurement errors could
be due to having a poor thermal contact between the
thermocouple junction and the surface, heat loss by
radiation, or by conduction through thermocouple
leads. To minimize the measurement errors, the
following approach is recommended:
•
Use a 35 gauge K-type thermocouple or
equivalent.
•
Attach the thermocouple bead or junction to the
package top surface at a location corresponding
to the center of the Pentium Pro processor die.
(Location A in Figure 38) Using the center of the
Pentium Pro processor die gives a more
accurate measurement and less variation as the
boundary condition changes
•
Attach the thermocouple bead or junction at a
90° angle by an adhesive bond (such as
thermal grease or heat-tolerant tape) to the
package top surface as shown in Figure 39.
When a heat sink is attached, a hole should be
drilled through the heat sink to allow probing the
Pentium Pro processor package above the
center of the Pentium Pro processor die. The
hole diameter should be no larger than 0.150."
E
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