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PID9v-604e Hardware Specifications

PRELIMINARY—SUBJECT TO CHANGE WITHOUT NOTICE

Figure 15. Thermalloy #2328B Heat Sink-to-Ambient Thermal Resistance Versus Airflow Velocity

Assuming an air velocity of 1 m/s, we have an effective

θ

sa of 5 °C/W, thus

Tj = 30 °C + 5 °C + (0.1 °C/W +1.0 °C/W + 5 °C/W) * 15 W,

resulting in a die-junction temperature of approximately 125

°C which exceeds the maximum operating

temperature of the component. To reduce the die junction temperature the designer has several options:

1. Increase the airflow velocity

2. Increase the surface area of the heat sink

3. Select a heat sink with an integrated cooling fan

Heat sinks offered by Chip Coolers, IERC, Thermalloy, Wakefield Engineering, and Aavid Engineering

offer different heat sink-to-ambient thermal resistances and air flow requirements.

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 using only these metrics 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

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3.5

Thermalloy #2328B Pin-fin Heat Sink

Approach Air Velocity (m/s)

(25 x 28 x 15 mm)

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Freescale Semiconductor, Inc.

For More Information On This Product,

Go to: www.freescale.com

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