3h rule

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hello every one . in my stackup the h1(distance between signal layer and upper ground) is 3.2 mil and h2(distance between signal layer and downer ground) is 4.2 . if i want to use 3h rule for minimize crosstalk i should use 3h1 or 3h2?

[binayak]

Your stripline configuration is more or less symmetric. Both planes will act as return planes. Normally you would take the lesser among h1 and h2.

How wide are your traces ? Normally for 50 ohm configuration:

(a) if edge to edge spacing (s) = trace width (w), we call it tightly coupled
(b) if s = 2w, we call it loosely coupled
(c) if s = 3w or more, we call it uncoupled

PS. Look at Dr. Eric Bogatin's "Signal integrity and power integrity simplified" for more information.

[robertferanec]

nearest reference plane:

"It is called the 3H rule. You may already be familiar with an implementation of this rule. 3H stands for three times the dielectric thickness or Height in the Z-axis from the signal layer to the nearest reference ground plane."

https://resources.pcb.cadence.com/blog/the-case-for-stitching-vias-on-your-pcb-2