Strange issue here. I’d like to increase the current that can be transported on a short trace from one through-hole pad to another by drawing a trace on both sides of the PCB between these two points. I’ve done that before (maybe with KiCad 5) but when I do it now, adding a trace on the same path as the previous, it always deletes the trace from the other side! I can only have that trace on one side not both now.
Why does KiCad do that and how can I stop it? I want traces on both sides, not a single side. As both ends already exist on both sides, it doesn’t cost me anything to have these two traces. There are no crossing traces or anything, this is a free area. I could draw either without a problem, but it will delete the other that I’ve just drawn before.
I’ve verified this by hiding each layer and see what’s left. But usually the active layer is always rendered on top so you could already see.
Okay, I googled that and most of what I found described audio effects. I’ve heard that effect before when connecting a TV with a stereo amp across the room many years ago when we still had analogue audio lines. A decoupling transformer helped back then.
My PCB now has a pulsed (PWM) LED power line of up to 2 A (24 V), not an audio signal. And my trace is a few millimetres long, 1 mm wide (standard 35 µm thickness) and runs exactly on the same path on both sides. The connectors are through-hole parts, so the connection is already accessible on both sides. From my limited experience I wouldn’t expect any issues here. But just in case, would placing vias along that double-sided trace be of any use here?
And since the problem seems to be mostly about ground loops: Isn’t a ground plane with a hole (making space for other traces) also a ground loop? I mean, the current could flow left and right of that hole, which is two paths.
I believe the reason why KiCad deletes redundant traces by default is simply to make editing easier. Like if you have a track that goes in an unnecessarily roundabout way, you simply draw the shorter/better route and KiCad will automatically delete the old path without you having to manually select and delete it.
Redundant ground traces are most often not a problem, if you have multiple ground planes and stitching vias and so on, you have redundancy pretty much by inevitably.