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參數(shù)資料
| 型號： | STPCD0110BTC3 |
| 元件分類： | 32位微控制器 |
| 英文描述： | 32-Bit Microprocessor |
| 中文描述： | 32位微處理器 |
| 文件頁數(shù)： | 54/61頁 |
| 文件大?。?/td> | 1007K |
| 代理商： | STPCD0110BTC3 |
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BOARD LAYOUT
54/61
Issue 2.2 - October 13, 2000
When considering thermal dissipation, the most
important - and not the more obvious - part of the
layout is the connection between the ground balls
and the ground layer.
A 1-wire connection is shown in
Figure 6-2
. The
use of a 8-mil wire results in a thermal resistance
of 105°C/W assuming copper is used (418 W/
m.°K). This high value is due to the thickness (34
μm) of the copper on the external side of the PCB.
Considering only the central matrix of 36 thermal
balls and one via for each ball, the global thermal
resistance is 2.9°C/W. This can be easily im-
proved by using four 10 mil wires to connect to the
four vias around the ground pad link as in
Figure
6-3
. This gives a total of 49 vias and a global resis-
tance for the 36 thermal balls of 0.6°C/W.
The use of a ground plane like in
Figure 6-4
is
even better.
To avoid solder wicking over to the via pads during
soldering, it is important to have a solder mask of
4 mil around the pad (NSMD pad), this gives a di-
ameter of 33 mil for a 25 mil ground pad.
To obtain the optimum ground layout, place the
vias directly under the ball pads. In this case no lo-
cal board distortion is tolerated.
The thickness of the copper on PCB layers is typ-
ically 34 μm for external layers and 17 μm for inter-
nal layers. This means thermal dissipation is not
good and temperature of the board is concentrat-
ed around the devices and falls quickly with in-
creased distance.
When it is possible to place a metal layer inside
the PCB, this improves dramatically the heat
spreading and hence thermal dissipation of the
board.
Figure 6-2. Recommended 1-wire ground pad layout
Figure 6-3. Recommended 4-wire ground pad layout
Solder Mask (4 mil)
Pad for ground ball (diameter = 25 mil)
Hole to ground layer (diameter = 12 mil)
Connection Wire (width = 10 mil)
Via (diameter = 24 mil)
345ml
1 mil = 0.0254 mm
4 via pads for each ground ball
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| STPCD0113BTC3 | 32-Bit Microprocessor |
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| STPCI2 | STPC ATLAS DATASHEET / X86 CORE PC COMPATIBLE SYSTEM-ON-CHIP FOR TERMINALS |
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| STPCD0112BTC3 | 制造商:未知廠家 制造商全稱:未知廠家 功能描述:32-Bit Microprocessor |
| STPCD0113BTC3 | 制造商:未知廠家 制造商全稱:未知廠家 功能描述:32-Bit Microprocessor |
| STPCD0166BTA3 | 制造商:STMICROELECTRONICS 制造商全稱:STMicroelectronics 功能描述:PC Compatible Embedded Microprocessor |
| STPCD0166BTC3 | 制造商:STMicroelectronics 功能描述:MPU STPC RISC 64-Bit 66MHz 388-Pin BGA |
| STPCD0166BTI3 | 制造商:STMICROELECTRONICS 制造商全稱:STMicroelectronics 功能描述:PC Compatible Embedded Microprocessor |
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