PCX745BVZFU350LE Atmel, PCX745BVZFU350LE Datasheet - Page 20

• Manufacturer Part Number: PCX745BVZFU350LE
• Description: IC MPU 32BIT 350MHZ 255PBGA
• Manufacturer: Atmel

Specifications of PCX745BVZFU350LE

• Processor Type: PowerPC 32-Bit RISC
• Speed: 350MHz
• Voltage: 2V
• Mounting Type: Surface Mount
• Package / Case: 255-PBGA
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Features: -

6.1.4
20
PC755/745
Adhesives and Thermal Interface Materials
Ultimately, the final selection of an appropriate heat sink depends on many factors, such as ther-
mal performance at a given air velocity, spatial volume, mass, attachment method, assembly,
and cost.
Figure 6-3.
A thermal interface material is recommended at the package lid-to-heat sink interface to mini-
mize the thermal contact resistance. For those applications where the heat sink is attached by
spring clip mechanism,
interface materials (silicone, graphite/oil, floroether 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 7 times greater than the thermal grease joint.
Heat sinks are attached to the package by means of a spring clip to holes in the printed-circuit
board (see
Therefore, the synthetic grease offers the best thermal performance, considering the low inter-
face pressure.
The board designer can choose between several types of thermal interface. Heat sink adhesive
materials should be selected based upon high conductivity, yet adequate mechanical strength to
meet equipment shock/vibration requirements.
1.5
0.5
2
1
0
Figure 6-2 on page
0
Thermal Performance of Select Thermal Interface Material
10
Figure 6-3
20
19). This spring force should not exceed 5.5 pounds of force.
shows the thermal performance of three thin-sheet thermal-
Contact Pressure (psi)
30
40
50
Silicone Sheet (0.006 inch)
Bare Joint
Floroether Oil Sheet (0.007 inch)
Graphite/Oil Sheet (0.005 inch)
Synthetic Grease
60
70
2138G–HIREL–05/06
80