Electronics > Manufacturing & Assembly

6 Layer PCB...General structure?

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Faringdon:
Hi,
With a 6 layer PCB, would you agree, that generally the following regime is optimum…..

you have a top layer for components.
Then one layer for ground
One layer for power.
Then one layer for inner layer tracks  running in direction “A”.
Then one layer  for inner layer tracks running in a direction at 90 degrees to “A”.

Then a spare layer, likely the bottom layer, which you can make another ground.

Siwastaja:
It can work that way but usually, layers are considered as pairs where each other is reference level (ground plane or Vcc plane well decoupled to ground) and the nearby layer is a signal layer. This way, each signal automagically has a return path in the nearby reference plane.

In your system, your "spare layer" which you make a ground works as a pair with the 90degA layer, and the A layer works as a pair with your power plane. So the above description is kind of satisfied, because in typical stackup, the distance between your two signal layers is larger.

Just your terminology makes me wonder this happened by luck. Now if A and A90deg layers were close together with thin prepreg separating them, these signal would couple together, which you would of course minimize by running them 90 degrees in different directions, but still, you can avoid the coupling completely by having every other layer as reference plane.

alexaraujo:

--- Quote from: Faringdon on November 07, 2021, 04:13:10 pm ---Hi,
With a 6 layer PCB, would you agree, that generally the following regime is optimum…..

you have a top layer for components.
Then one layer for ground
One layer for power.
Then one layer for inner layer tracks  running in direction “A”.
Then one layer  for inner layer tracks running in a direction at 90 degrees to “A”.

Then a spare layer, likely the bottom layer, which you can make another ground.

--- End quote ---
.

About Stackup I use some concepts taken from this video with Robert Feranec and Rick Hartley below but also from a document I keep since college.



Hope this helps.

Feynman:
Yeah, just search for Rick Hartley on youtube. There are several videos with him talking about good and bad 6-layer stack-ups.

alexaraujo:
I use model 4 as shown in the table below.

I hope it helped you

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