Intel Pentium 4 Processor on 90 nm Process Thermal and Mechanical Design Guidelines

Thermal Requirements
R
Intel
®
Pentium
®
4 on 90 nm Process Thermal Design Guide 23
Figure 5. Locations for Measuring Local Ambient Temperature, Passive Heatsink (not to
scale)
3.3.3 Processor Case Temperature Measurement Guidelines
To ensure functionality and reliability, the Pentium 4 processor on 90 nm process is specified for
proper operation when T
C
is maintained at or below the thermal profile as listed in the Intel
®
Pentium
®
4 Processor on 90 nm Process Datasheet. The measurement location for T
C
is the
geometric center of the IHS. Figure 1 shows the location for T
C
measurement.
Special care is required when measuring T
C
to ensure an accurate temperature measurement.
Thermocouples are often used to measure T
C
. Before any temperature measurements are made,
the thermocouples must be calibrated, and the complete measurement system must be routinely
checked against known standards. When measuring the temperature of a surface that is at a
different temperature from the surrounding local ambient air, errors could be introduced in the
measurements. The measurement errors could be caused by poor thermal contact between the
thermocouple junction and the surface of the integrated heat spreader, heat loss by radiation,
convection, by conduction through thermocouple leads, or by contact between the thermocouple
cement and the case. To minimize these measurement errors, the approach is outlined in
Appendix D: T
CASE
Reference Metrology.