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Board Layout Guidelines
This section provides details on the motherboard and adapter card stackup suggestions. It is highly
recommended that signal integrity simulations be run to verify each 80331 PCB layout especially
when it deviates from the recommendations listed in these design guidelines. The information in
this chapter is an example of a stackup for a motherboard and an adapter card which can be used as
a reference.
5.1
Motherboard Stack Up Information
When 80331 is used in server and workstation Raid On Mother Board (ROMB) applications the
motherboard is implemented on eight layers. The specified impedance range for all board
implementations are 50 ohms +/-15%. Adjustments are made for interfaces specified at other
impedances.
The motherboard is supporting other components in addition to 80331, so it is assumed that
server/workstation motherboard requirements dominates to assure the processor and memory
subsystem can be implemented with typical 50-ohm guidelines. Dimensions and tolerances for the
motherboard are per
Table 5.
Motherboard Stack Up, Stripline and Microstrip (Sheet 1 of 2)
Variable
Solder Mask
Thickness (mil)
Solder Mask E
r
Core Thickness (mil)
Core E
r
Plane Thickness
(mil)
Ground
Trace Height (mil)
Microstrip
Stripline1
Preg E
r
Stripline2
Microstrip
Trace Thickness
(mil)
Stripline
Trace Width (mil)
Microstrip
Table 5
defines the typical layer geometries for six or eight layer boards.
Table
5. Refer to
Nominal
Minimum
Type
(mils)
(mils)
N/A
0.8
0.6
N/A
3.65
3.65
N/A
9.8
9.6
N/A
4.30
3.75
Power
2.7
2.5
1.35
1.15
1
3.5
3.3
2
3.5
3.3
3
10.5
9.9
4.30
3.75
4.30
3.75
4.66
4.19
1.75
1.2
1.4
1.2
5.0
3.5
Intel® 80331 I/O Processor Design Guide
Figure 12
for location of variables in
Maximum
(mils)
1.0
The trace height is determined to achieve a nominal
3.65
50 ohms.
10
4.85
2113 material.
2.9
1.55
3.7
3.7
11.1
4.85
2113 material.
4.85
2113 material.
7628 material. Trace height 3 is composed of one
piece of 2113 and one piece of 7628. It is assumed
that the 7628 material covers the bottom and sides
5.13
of the layer 3 traces as well as the top and sides of
the layer 4 traces. The 2113 material covers the top
of the layer three traces and the bottom of the layer
4 traces.
2.3
1.6
6.5
Board Layout Guidelines
Table
5.
Notes
5
37
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