Layout Guidelines; Pcb Stack-Ups; Four-Layer Stack-Up; Six-Layer Stack-Up - Emerson COM Express Carrier Design Manual

21 Layout Guidelines

21.1 PCB Stack-ups

This section assumes that the thickness for the carrier PCB is 0.62 in. Other PCB mechanics are
possible, but the described stack-ups need to be adapted.

21.1.1 Four-Layer Stack-up

Figure 36 Four Layer Stack-Up
This figure 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.

21.1.2 Six-Layer Stack-up

Figure 37 Six Layer Stack-Up
COM Express Carrier Type 2
Design Guide
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