Four Layer Board Stack-Up - Advantech SOM-ETX Series Design Manual

4.1.1 Four layer board stack-up

Figure 4.1 illustrates an example of a four-layer stack-up with 2 signal layers and 2
power planes. The two power planes are the power layer and the ground layer. The
layer sequence of component-ground-power-solder is the most common stack-up
arrangement from top to bottom.
Figure 4-1 Four-Layer Stack-up with 2 Signal Layers and 2 Power Planes
Dielectric Layer Layer
Thickness
(mil)
No Type
0.7 L1 Signals
5 Prepreg
1.4 L2 Ground
47 Core
1.4 L3 Power
5 Prepreg
0.7 L4 Signals
Notes :
Target PCB Thickness totals 62mil+/-10%
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Advantech SOM-ETX Design Guide
L1 Signal Layer
Prepreg
L2 Ground Layer
Core
L3 Power Layer
Prepreg
L4 Signal Layer
Signal-End Signals
Width Impedance
(mil) (ohm)
6/6 55+/-10%
6/6 55+/-10%
Chapter 4 General Design Recommendations
Thickness
62 mils
USB differential
Differential Signals
Signals
Width Impedance Width
(mil) (ohm) (mil)
6/7/6 100+/-10% 6/5/6
6/7/6 100+/-10% 6/5/6
Total
Impedance
(ohm)
90+/-10%
90+/-10%