Freescale Semiconductor MPC8358E Hardware Specificftion page 100

Thermal
R = junction-to-case thermal resistance (°C/W)
θ
JC
R = case-to-ambient thermal resistance (°C/W)
θ
CA
R is device related and cannot be influenced by the user. The user controls the thermal environment to
θ
JC
change the case-to-ambient thermal resistance, R
sink, the airflow around the device, the interface material, the mounting arrangement on printed-circuit
board, or change the thermal dissipation on the printed-circuit board surrounding the device.
To illustrate the thermal performance of the devices with heat sinks, the thermal performance has been
simulated with a few commercially available heat sinks. The heat sink choice is determined by the
application environment (temperature, airflow, adjacent component power dissipation) and the physical
space available. Because there is not a standard application environment, a standard heat sink is not
required.
Table 78 shows heat sinks and junction-to-ambient thermal resistance for TBGA package.
Table 78. Heat Sinks and Junction-to-Ambient Thermal Resistance of TBGA Package
Heat Sink Assuming Thermal Grease
AAVID 30 × 30 × 9.4 mm pin fin
AAVID 30 × 30 × 9.4 mm pin fin
AAVID 30 × 30 × 9.4 mm pin fin
AAVID 31 × 35 × 23 mm pin fin
AAVID 31 × 35 × 23 mm pin fin
AAVID 31 × 35 × 23 mm pin fin
Wakefield, 53 × 53 × 25 mm pin fin
Wakefield, 53 × 53 × 25 mm pin fin
Wakefield, 53 × 53 × 25 mm pin fin
MEI, 75 × 85 × 12 no adjacent board, extrusion
MEI, 75 × 85 × 12 no adjacent board, extrusion
MEI, 75 × 85 × 12 no adjacent board, extrusion
MEI, 75 × 85 × 12 mm, adjacent board, 40 mm side bypass
Accurate thermal design requires thermal modeling of the application environment using computational
fluid dynamics software which can model both the conduction cooling and the convection cooling of the
air moving through the application. Simplified thermal models of the packages can be assembled using the
junction-to-case and junction-to-board thermal resistances listed in the thermal resistance table. More
detailed thermal models can be made available on request.
MPC8360E/MPC8358E PowerQUICC II Pro Processor Revision 2.x TBGA Silicon Hardware Specifications, Rev. 4
100
. For instance, the user can change the size of the heat
θ
CA
Airflow
Natural convention
1 m/s
2 m/s
Natural convention
1 m/s
2 m/s
Natural convention
1 m/s
2 m/s
Natural convention
1 m/s
2 m/s
1 m/s
35 × 35 mm TBGA
Junction-to-Ambient
Thermal Resistance
10.7
6.2
5.3
8.1
4.4
3.7
5.4
3.2
2.4
6.4
3.8
2.5
2.8
Freescale Semiconductor