Intel
®
945G Express Chipset GMCH Thermal Design Guide
Thermal Metrology
3 Thermal
Metrology
The system designer must measure temperatures in order to accurately determine the thermal
performance of the system. Intel has established guidelines for proper techniques of measuring
chipset component case temperatures.
3.1
Case Temperature Measurements
To ensure functionality and reliability, the chipset GMCH is specified for proper operation when
T
C
is maintained at or below the maximum temperature listed in Table 2. The surface temperature
at the geometric center of the die corresponds to T
C
. Measuring T
C
requires special care to ensure
an accurate temperature reading.
Temperature differences between the temperature of a surface and the surrounding local ambient
air can introduce error in the measurements. The measurement errors could be due to a poor
thermal contact between the thermocouple junction and the surface of the package, heat loss by
radiation and/or convection, conduction through thermocouple leads, or contact between the
thermocouple cement and the heat sink base. To minimize these measurement errors a
thermocouple attach with a zero-degree methodology is recommended.
3.1.1 Thermocouple
Attach
Methodology
1.
Mill a 3.3 mm (0.13 in.) diameter hole centered on bottom of the heat sink base. The milled
hole should be approximately 1.5 mm (0.06 in.) deep.
2.
Mill a 1.3 mm (0.05 in.) wide slot, 0.5 mm (0.02 in.) deep, from the centered hole to one edge
of the heat sink. The slot should be parallel to the heat sink fins (see Figure 3).
3.
Attach thermal interface material (TIM) to the bottom of the heat sink base.
4.
Cut out portions of the TIM to make room for the thermocouple wire and bead. The cutouts
should match the slot and hole milled into the heat sink base.
5.
Attach a 36-gauge or smaller calibrated K-type thermocouple bead or junction to the center of
the top surface of the die using a high thermal conductivity cement. During this step, make
sure no contact is present between the thermocouple cement and the heat sink base because
any contact will affect the thermocouple reading.
Caution:
It is critical that the thermocouple bead makes contact with the die (see Figure 2).
6.
Attach heat sink assembly to the GMCH, and route thermocouple wires out through the
milled slot.
Figure 2
0° Angle Attach Methodology (Top View)
NOTE:
Drawing not to scale.
Order #308643
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