MC7448VU1700LD Freescale Semiconductor, MC7448VU1700LD Datasheet - Page 48

• Manufacturer Part Number: MC7448VU1700LD
• Description: IC MPU RISC 32BIT 360-FCCBGA
• Manufacturer: Freescale Semiconductor

Specifications of MC7448VU1700LD

• Processor Type: MPC74xx PowerPC 32-Bit
• Speed: 1.7GHz
• Voltage: 1.3V
• Mounting Type: Surface Mount
• Package / Case: 360-FCCBGA
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Features: -

System Design Information
9.7.1
For the exposed-die packaging technology described in
paths are as follows:
Figure 24
printed-circuit board.
Heat generated on the active side of the chip is conducted through the silicon, through the heat sink attach
material (or thermal interface material), and, finally, to the heat sink, where it is removed by forced-air
convection.
Because the silicon thermal resistance is quite small, the temperature drop in the silicon may be neglected
for a first-order analysis. Thus, the thermal interface material and the heat sink conduction/convective
thermal resistances are the dominant terms.
9.7.2
A thermal interface material is recommended at the package lid-to-heat sink interface to minimize the
thermal contact resistance. For those applications where the heat sink is attached by spring clip
mechanism,
(silicone, graphite/oil, fluoroether oil), a bare joint, and a joint with thermal grease as a function of contact
pressure. As shown, the performance of these thermal interface materials improves with increasing contact
pressure. The use of thermal grease significantly reduces the interface thermal resistance. That is, the bare
joint results in a thermal resistance approximately seven times greater than the thermal grease joint.
Often, heat sinks are attached to the package by means of a spring clip to holes in the printed-circuit board
(see
pressure and is recommended due to the high power dissipation of the MPC7448. Of course, the selection
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Figure
The die junction-to-case thermal resistance (the case is actually the top of the exposed silicon die)
The die junction-to-board thermal resistance
depicts the primary heat transfer path for a package with an attached heat sink mounted to a
22). Therefore, synthetic grease offers the best thermal performance due to the low interface
Internal Package Conduction Resistance
Thermal Interface Materials
Figure 25
(Note the internal versus external package resistance.)
Figure 24. C4 Package with Heat Sink Mounted to a Printed-Circuit Board
External Resistance
External Resistance
Internal Resistance
shows the thermal performance of three thin-sheet thermal-interface materials
MPC7448 RISC Microprocessor Hardware Specifications, Rev. 4
Printed-Circuit Board
Heat Sink
Radiation
Radiation
Table
Convection
Convection
5, the intrinsic conduction thermal resistance
Thermal Interface Material
Die/Package
Die Junction
Package/Leads
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