MPC8540CPX667JC datasheet(88/104 Pages) FREESCALE

88 / 104 page

MPC8540 Integrated Processor Hardware Specifications, Rev. 4

Freescale Semiconductor

Thermal

Figure 50. Exploded Views (2) of a Heat Sink Attachment using a Plastic Fence

The die junction-to-ambient and the heat sink-to-ambient thermal resistances are common figure-of-merits

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), 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 boards, as well as, system-level designs.

MPC8540CPX667JC Datasheet(PDF) 88 Page - Freescale Semiconductor, Inc