CLIENT ST Microelectronics, Inc., CLIENT Datasheet - Page 55

• Manufacturer Part Number: CLIENT
• Description: STPC Client Datasheet / PC Compatible Embeded Microprocessor
• Manufacturer: ST Microelectronics, Inc.

The PBGA Package also dissipates heat through
peripheral ground balls. When a heat sink is
placed on the device, heat is more uniformely
spread throughout the moulding increasing heat
dissipation through the peripheral ground balls.
Figure 6-4. Optimum layout for central ground ball
Figure 6-5. Global ground layout for good thermal dissipation
Issue 2.2 - October 13, 2000
The more via pads are connected to each ground
ball, the more heat is dissipated . The only limita-
tion is the risk of lossing routing channels.
Figure 6-5
between thermal dissipation and number of rout-
ing channels.
shows a routing with a good trade off
Clearance = 6mil
External diameter = 37 mil
Via to Ground layer
hole diameter = 14 mil
Solder mask
diameter = 33 mil
Pad for ground ball
diameter = 25 mil
connections = 10 mil
Via to ground layer
Ground pad
BOARD LAYOUT
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