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Table 10-2. Example Thermal Solution Performance for 266 MHz Pentium
Thermal Solution Performance
Θ thermal plate to ambient (°C/watt)
The Θ
thermal plate to ambient
resistance between the thermal plate and heatsink (Θ
resistance between the heatsink and the ambient air around the processor (Θ
critical but controllable factor to decrease the value of Θ
of the thermal interface between the thermal plate and heatsink. The other controllable factor
(Θ
) is determined by the design of the heatsink and airflow around the heatsink.
heatsink to air
Heatsink design constraints are also provided in AP-586, Pentium
Design Guidelines (Order Number 243333) and thermal interfaces are addressed in AP-586,
®
Pentium
II Processor Thermal Design Guidelines (Order Number 243333).
10.2.2. Measurements for Thermal Specifications
10.2.2.1.
THERMAL PLATE TEMPERATURE MEASUREMENT
To ensure functional and reliable Pentium II processor operation, the thermal plate
temperature (T
) must be maintained at or below the maximum T
PLATE
at or above the minimum T
location for T
measurement.
PLATE
Special care is required when measuring T
measurement. Thermocouples are used to measure T
measurements, the thermocouples must be calibrated. When measuring the temperature of a
surface, errors can be introduced in the measurement if not handled properly. The
measurement errors can be due to a poor thermal contact between the thermocouple junction
and the surface of the thermal plate, conduction through thermocouple leads, heat loss by
radiation and convection, or by contact between the thermocouple cement and the heatsink
base. To minimize these errors, the following approach is recommended:
•
Use 36 gauge or finer diameter K, T, or J type thermocouples. Intel's laboratory testing
was done using a thermocouple made by Omega* (part number: 5TC-TTK-36-36).
•
Attach the thermocouple bead or junction to the top surface of the thermal plate at the
location specified in Figure 10-2 using high thermal conductivity cements.
•
The thermocouple should be attached at a 0° angle if no heatsink is attached to the
thermal plate. If a heatsink is attached to the thermal plate but the heatsink does not
THERMAL SPECIFICATIONS AND DESIGN CONSIDERATIONS
at Thermal Plate Power of 37.0 Watts
35°C
1.08
value is made up of two primary components: the thermal
temperature specified in Table 10-1. Figure 10-2 shows the
PLATE
PLATE
Local Ambient Temperature (T
40°C
0.95
thermal plate to heatsink
thermal plate to heatsink
®
II Processor Thermal
PLATE
to ensure an accurate temperature
. Before taking any temperature
PLATE
®
II Processor
)
LA
45°C
0.81
) and the thermal
). A
heatsink to air
is management
temperature and
10-3
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