Hello,
I am using Ki-cad 6.0.2 for layout designing. I am designing 4 layer PCB. I want to assign differential net class to different layer.I have created one net class of 100 ohm and assigned it to differential pair. I want to set the constraints of differential pair for different layers so How can i do that?
First:
Update Kicad!
KiCad V6 is quite new, (released last december) and it now sees a lot bigger user base and quite a lot of small bugs are being found and fixed.
KiCad V6.0.4 was released 3 days before you posted this.
In KiCad, setup of net classes is in Pcb Editor / File / Board Setup / Design rules / Net Classes
The scope of a net class is along the whole net, and there is only one setting for each net class.
As far as I know, KiCad can not use different settings for different layers of the same net or net class.
The only workaround I know is to work with net-ties, and then separate your track into different nets, but this will be a real nuisance to do.
I don’t have much experience with differential pairs, but this request seems fairly logical. As far as I know impedance of a transmission line changes between internal and external layers of a PCB, and the differential pair dimensions should match that. Maybe there already is an issue or feature request for this on gitlab.
But also: Because of the impedance changes, it’s probably better to avoid the whole issue by not switching a differential pair between an internal and external layers in the first place. And this is probably why it is not implemented (yet) in KiCad.
I have already updated the version to kicad 6.0.4. Is it possible with custom rules?
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