Kontron COMe Starterkit Eval T2 - Manual (Page 173)

Carrier Board PCB Layout Guidelines
6. Carrier Board PCB Layout Guidelines
6.1. General
6.2. PCB Stack-ups
Note Section 6 'Carrier Board PCB Layout Guidelines' assumes a thickness for the
carrier PCB to be 0.0625 inches. Other PCB mechanics are possible but the
described Stack-ups need to be adapted.
6.2.1. Four-Layer Stack-up
Figure 68: Four-Layer Stack-up
Figure 68 above is an example of a four layer stack-up. Layers L1 and L4 are used for signal
routing.
Layers L2 and L3 are used for solid ground and power planes respectively.
Microstrips on Layers 1 and 4 reference ground and power planes on Layers 2 and 3
respectively.
In some cases, it may be advantageous to swap the GND and PWR planes. This allows Layer 4
to be GND referenced. Layer 4 is clear of parts and may be the preferred primary routing layer.
6.2.2. Six-Layer Stack-up
Figure 69: Six-Layer Stack-up
PICMG ® COM Express ® Carrier Board Design Guide Rev. 2.0 / December 6, 2013
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GND Plane
Power Plane
L1
L2
L3
L4
Power Plane
GND Plane
L 1
L 2
L 3
L 4
L 5
L 6