mpc8245ec Freescale Semiconductor, Inc, mpc8245ec Datasheet - Page 52

• Manufacturer Part Number: mpc8245ec
• Description: Mpc8245 Integrated Host Processor
• Manufacturer: Freescale Semiconductor, Inc

System Design
Selection of an appropriate heat sink depends on thermal performance at a given air velocity, spatial
volume, mass, attachment method, assembly, and cost. Other heat sinks offered by Aavid Thermalloy,
Alpha Novatech, IERC, Chip Coolers, and Wakefield Engineering offer different heat sink-to-ambient
thermal resistances and may or may not need airflow.
7.8.1
The intrinsic conduction thermal resistance paths for the TBGA cavity-down packaging technology shown
in
Figure 29
printed-circuit board.
In a TBGA package, the active side of the die faces the printed-circuit board. Most of the heat travels
through the die, across the die attach layer, and into the copper spreader. Some of the heat is removed from
the top surface of the spreader through convection and radiation. Another percentage of the heat enters the
printed-circuit board through the solder balls. The heat is then removed from the exposed surfaces of the
board through convection and radiation. If a heat sink is used, a larger percentage of heat leaves through
the top side of the spreader.
52
Figure 29
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Wakefield Engineering
33 Bridge St.
Pelham, NH 03076
Internet: www.wakefield.com
Die junction-to-case thermal resistance
Die junction-to-ball thermal resistance
depicts the primary heat transfer path for a package with an attached heat sink mounted on a
Internal Package Conduction Resistance
are as follows:
Figure 29. TBGA Package with Heat Sink Mounted to a Printed-Circuit Board
(Note the internal versus external package resistance)
External Resistance
External Resistance
Internal Resistance
MPC8245 Integrated Processor Hardware Specifications, Rev. 10
Printed-Circuit Board
Heat Sink
Radiation
Radiation
Convection
Convection
603-635-5102
Thermal Interface Material
Die/Package
Die Junction
Package/Leads
Freescale Semiconductor