Thermal
The spring mounting should be designed to apply the force only directly above the die. By localizing the
force, rocking of the heat sink is minimized. One suggested mounting method attaches a plastic fence to
the board to provide the structure on which the heat sink spring clips. The plastic fence also provides the
opportunity to minimize the holes in the printed-circuit board and to locate them at the corners of the
package. Figure 49 and Figure 50 provide exploded views of the plastic fence, heat sink, and spring clip.
Figure 49. Exploded Views (1) of a Heat Sink Attachment using a Plastic Force
MPC8540 Integrated Processor Hardware Specifications, Rev. 4
Freescale Semiconductor
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FREESCALE [ Freescale ]
