Four Layer Board Stack-Up; Six Layer Board Stack-Up With 4 Signal Planes And 2 Power Planes - Intel 440GX Design Manual

Motherboard Layout and Routing Guidelines
Figure 2-4. Four Layer Board Stack-up
Z = 60 ohms
Z = 60 ohms
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.
Note: A thicker core may help reduce board warpage issues.
For a dual processor / Intel
examples are shown below.
Figure 2-6
to accommodate all of the power planes required in a Intel
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.
Figure 2-5. Six Layer Board Stack-up With 4 Signal Planes and 2 Power Planes
Z = 66 ohms
Z = 73 ohms
Z = 66 ohms
2-4
5 mils
47 mils
5 mils
®
440GX AGPset design, a 6 layer stack-up is recommended. Two
Figure 2-5
shows 3 signal plane layers and 3 power plane layers. The second option makes it easier
6 mils
18 mils
6 mils
18 mils
6 mils
Primary Signal Layer (1/2 oz. cu.)
PREPREG
Ground Plane (1 oz. cu.)
CORE
Power Plane (1 oz. cu)
PREPREG
Secondary Signal Layer (1/2 oz. cu)
Total board thickness = 62.6
has 4 signal plane layers and 2 power plane layers.
®
440GX AGPset design.
Primary Signal Layer (1/2 oz. cu.)
PREPREG
Ground Plane (1 oz. cu.)
CORE
Inner Layer #1 (1 oz. cu.)
PREPREG
Inner Layer #2 (1 oz. cu)
CORE
Power Plane (1 oz. cu)
PREPREG
Secondary Signal Layer (1/2 oz. cu)
Total board thickness = 62.4
Intel
®
440GX AGPset Design Guide