39
Board Layout Guidelines
5.2
Adapter Card Stackup
The 80331 can be implemented on PCI-X adapter cards with six or eight layer stackups. The
specified impedance range for all adapter card implementations are /-15%. Adjustments
are made for interfaces specified at other impedances.
defines the typical layer geometries
for six or eight layer boards.
Note:
Values are the same as the motherboard stack up with the exception of the impedance.
NOTE:
Each interface sets the trace spacing based on its signal integrity of differential impedance
requirements. For the purposes of the building the transmission line models, it is assumed the artwork is
very accurate and therefore a constant. Thus, all the variability in the trace spacing is the result of the
tolerances of the trace width.
Table 6.
Adapter Card Stack Up, Microstrip and Stripline
Variable
Type
Nominal
(mils)
Minimum
(mils)
Maximum
(mils)
Notes
Solder Mask Thickness (mil)
N/A
0.8
0.6
1.0
Solder Mask E
r
N/A
3.65
3.65
3.65
Core Thickness (mil)
N/A
2.8
3.0
3.2
Core E
r
N/A
4.3
3.75
4.85
2113 material
Plane Thickness (mil)
Power
2.7
2.5
2.9
Ground
1.35
1.15
1.55
Trace Height
(mil)
1
3.5
3.3
3.7
The trace height is determined to achieve a
nominal 60 ohms.
2
3.5
3.3
3.7
3
10.5
9.9
11.1
Preg E
r
Microstrip
4.30
3.75
4.85
2113 material
Stripline1
4.30
3.75
4.85
2113 material
Stripline2
4.3
3.75
4.85
7628 material. Trace height 3 is composed
of one piece of 2113 and one piece of
7628.
Trace Thickness (mil)
Microstrip
1.75
1.2
2.3
Stripline
1.4
1.2
1.6
Trace Width (mil)
Microstrip
4.0
2.5
5.5
Stripline
4.0
2.5
5.5
Total Thickness (mil)
FR4
62.0
56.0
68.0
Trace Spacing (using
microstrip E2E/C2C)
[12]/[16]
Trace Spacing (using
stripline E2E/C2C)
[12]/[16]
Trace Impedance
Microstrip
60
51
69
Stripline
60
51
69
Summary of Contents for 80331
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