Thermal Metrology
R
Intel
®
E7500/E7505 Chipset MCH Thermal Design Guide
17
5
Thermal Metrology
The system designer must make temperature measurements to accurately determine the thermal
performance of the system. Intel has established guidelines for proper techniques of measuring the
MCH die temperature. Section 5.1 provides guidelines on how to accurately measure the MCH die
temperatures. Section 5.2 contains information on running an application program that will
emulate anticipated maximum thermal design power. The flowchart in Figure 6 offers guidelines
for thermal performance and evaluation.
5.1
Die Temperature Measurements
To ensure functionality and reliability, the T
case
of the MCH must be maintained at or below the
maximum temperature specifications as noted in Table 1 and Table 2. The surface temperature at
the geometric center of the die corresponds to T
case
. Measuring T
case
requires special care to ensure
an accurate temperature measurement.
Temperature differences between the temperature of a surface and the surrounding local ambient
air can introduce errors 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 heatsink base (if a heatsink is used). To maximum measurement
accuracy, only the 0° degree thermocouple attach approach is recommended for thermocouple
attach.
5.1.1
0° Angle Attach Methodology
1. Mill a 3.3 mm (0.13 in.) diameter and 1.5 mm (0.06 in.) deep hole centered on the bottom of
the heatsink base.
2. Mill a 1.3 mm (0.05 in.) wide and 0.5 mm (0.02 in.) deep slot, from the centered hole to one
edge of the heatsink. The slot should be in the direction parallel to the heatsink fins
(see Figure 5).
3. Attach thermal interface material (TIM) to the bottom of the heatsink 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 heatsink 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 high thermal conductivity cement. During this step, make sure
no contact is present between the thermocouple cement and the heatsink base because any
contact will affect the thermocouple reading.
It is critical that the thermocouple bead
makes contact with the die
6. Attach heatsink assembly to the MCH, and route thermocouple wire out through the milled
slot.
