Intel 440GX ユーザーズマニュアル
Motherboard Layout and Routing Guidelines
2-4
Intel
®
440GX AGPset Design Guide
Note:
The top and bottom routing layers specify 1/2 oz. cu. However, by the time the board is plated, the
traces will end about 1 oz. cu. Check with your fabrication vendor on the exact value and insure
that any signal simulation accounts for this value.
traces will end about 1 oz. cu. Check with your fabrication vendor on the exact value and insure
that any signal simulation accounts for this value.
Note:
A thicker core may help reduce board warpage issues.
For a dual processor / Intel
®
440GX AGPset design, a 6 layer stack-up is recommended. Two
examples are shown below.
Figure 2-5
has 4 signal plane layers and 2 power plane layers.
Figure 2-6
shows 3 signal plane layers and 3 power plane layers. The second option makes it easier
to accommodate all of the power planes required in a Intel
®
440GX AGPset design.
If a 6 layer stack-up is used, then it is recommended to route most of the GTL+ bus signals on the
inner layers. The primary and secondary signal layer can be used for GTL+ signals where needed.
Routes on the two inner layers should be orthogonal to reduce crosstalk between the layers.
inner layers. The primary and secondary signal layer can be used for GTL+ signals where needed.
Routes on the two inner layers should be orthogonal to reduce crosstalk between the layers.
Figure 2-4. Four Layer Board Stack-up
Primary Signal Layer (1/2 oz. cu.)
Ground Plane (1 oz. cu.)
Power Plane (1 oz. cu)
Secondary Signal Layer (1/2 oz. cu)
5 mils
47 mils
5 mils
PREPREG
CORE
PREPREG
Z = 60 ohms
Z = 60 ohms
Total board thickness = 62.6
Figure 2-5. Six Layer Board Stack-up With 4 Signal Planes and 2 Power Planes
Primary Signal Layer (1/2 oz. cu.)
Ground Plane (1 oz. cu.)
Inner Layer #1 (1 oz. cu.)
Inner Layer #2 (1 oz. cu)
Power Plane (1 oz. cu)
Secondary Signal Layer (1/2 oz. cu)
6 mils
18 mils
6 mils
18 mils
6 mils
PREPREG
PREPREG
PREPREG
CORE
CORE
Z = 66 ohms
Z = 73 ohms
Z = 66 ohms
Total board thickness = 62.4