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8
7
6
5
4
3
2
1
0
Figure 16. Thermalloy #2328B Heat Sink-to-Ambient Thermal Resistance Versus Airflow Velocity
Assuming an air velocity of 0.5 m/s, we have an effective R
= 30 °C + 5 °C + (2.2 °C/W +1.0 °C/W + 7 °C/W) * 3.0 W,
T
j
resulting in a die-junction temperature of approximately 66 °C which is well within the maximum operating
temperature of the component.
Other heat sinks offered by Chip Coolers, IERC, Thermalloy, Wakefield Engineering, and Aavid
Engineering offer different heat sink-to-ambient thermal resistances, and may or may not need air flow.
Though the die junction-to-ambient and the heat sink-to-ambient thermal resistances are a common figure-
of-merit used for comparing the thermal performance of various microelectronic packaging technologies,
one should exercise caution when only using this metric in determining thermal management because no
single parameter can adequately describe three-dimensional heat flow. The final die-junction operating
temperature, is not only a function of the component-level thermal resistance, but the system-level design
and its operating conditions. In addition to the component's power consumption, a number of factors affect
the final operating die-junction temperature—airflow, board population (local heat flux of adjacent
components), heat sink efficiency, heat sink attach, heat sink placement, next-level interconnect technology,
system air temperature rise, altitude, etc.
Due to the complexity and the many variations of system-level boundary conditions for today's
microelectronic equipment, the combined effects of the heat transfer mechanisms (radiation, convection and
conduction) may vary widely. For these reasons, we recommend using conjugate heat transfer models for
the board, as well as, system-level designs. To expedite system-level thermal analysis, several "compact"
thermal-package models are available within FLOTHERM®. These are available upon request.
603 Hardware Specifications
Thermalloy #2328B Pin-fin Heat Sink
0.5
1
1.5
Approach Airflow Velocity
Approach Airflow Velocity (m/s)
(25 x 28 x 15 mm)
2
2.5
3
(m/s)
of 7 °C/W, thus
sa
3.5
27
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