Can't make curved tracks

Bug #1577958 reported by robotarmy
280
This bug affects 64 people
Affects Status Importance Assigned to Milestone
KiCad
Fix Released
Unknown

Bug Description

It's essential for some high speed and RF layout to be able to easily create curved tracks using arcs (or maybe even NURBS splines?)

My current method involves drawing an arc on a non-copper layer and tracing around it with copper and that's bunk.

Tags: pcbnew
Changed in kicad:
importance: Undecided → Wishlist
Jeff Young (jeyjey)
Changed in kicad:
status: New → Triaged
Revision history for this message
sto (f4eru) wrote :

Curved tracks are a must for Flex PCBs to avoid stress concentration in the flexible zones.

tags: added: pcbnew
Revision history for this message
m (easyw) wrote :
Revision history for this message
Benjamin (benjwy) wrote :

I've read the forum discussion which devolved into devs attaching images of electric fields showing that curved traces are not necessary. That's a big call to make.

It is disappointing that the developers of the project are excluding a feature due to their "superior" EM knowledge. In the RF/microwave industry, no package will be taken seriously if it can't do curved traces. In fact even when using professional tools like Allegro we have always done the geometries in AWR/ADS and imported the GDSII.

If Kicad's goal is to remain in the hobbyist arena, then this decision is justified. If they really want to challenge Altium and Cadence then something will have to be done about this feature.

Appreciate all the effort the devs make, but this call sounds crazy to me.

Revision history for this message
Seth Hillbrand (sethh) wrote :

@benjwy- Always better to start with questions than assumptions here.

No one is excluding curved tracks. Certainly no devs are claiming superior EM knowledge. We've in feature freeze for v5 right now. New features like this will need to wait for v6.

You can find some relevant dev discussion at https://lists.launchpad.net/kicad-developers/msg29878.html

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Hildo Guillardi Júnior (hildogjr) wrote :
Revision history for this message
Benjamin (benjwy) wrote :

@sethh- Yup, fair enough.

On reflection, it was an assumption it was a developer - but someone arguing for excluding a feature like curved traces because it was a "technical myth" made my internet frustration levels rise!

Looking forward to the feature in v6. Would love to help out, but my software skills are probably not up to it.

Cheers

Revision history for this message
Sebastian Kulik (sebastiankulik1) wrote :

Hi guys,
I switched from Altium ti KiCAD a year ago and bevery very happy.
One of features iI really missing: rounded traces. Its possible to do them with some workarounds, but not really elegant and some of them looks ugly as well.
It will be really nice to have this feature built in.
Best regards from Germany,
Seb

Seth Hillbrand (sethh)
Changed in kicad:
assignee: nobody → Seth Hillbrand (sethh)
milestone: none → 6.0.0-rc1
status: Triaged → In Progress
Revision history for this message
Paul van der hoeven (paulvdh) wrote :

Link below is for a flex PCB which is difficult to design without arcs in tracks.
https://forum.kicad.info/t/curved-tracks-free-form-drawing/17746

At the moment I've suggested to draw the arcs with custom graphics in a separate footprint, as it is the only way I know to do it now

Revision history for this message
RyanFav (rerouter) wrote :

Being able to use the existing graphic arc tool, but able to assign a netlist so DRC does not get upset would be an ideal minimum,

Revision history for this message
John Cope (johnbentcope) wrote :

This would greatly assist in layout out radially organized PCBs. I'd also support assigning a netlist to shapes drawn with the arc tool as a minimum.

Revision history for this message
Christian Walther (cwalther) wrote :

One reason I haven’t seen mentioned yet for wanting curved tracks: aesthetics. Angled tracks just look ugly in most cases. If you want to design boards that aren’t just functional, but also look good (prime example: https://boldport.com), curved tracks are indispensable.

I would not even necessarily need convenient GUI tools to create and manipulate them, I’m okay with making these myself, but the ability to represent them in the data structures, display them, and e.g. handle them correctly in the DRC is essential.

Here is a board I made in Eagle (also with custom-made tools): https://twitter.com/isziaui/status/1194012165935706112
I would like to be able to make the same thing in KiCad.

Revision history for this message
Robert Leyland (rleyland) wrote :

Additional reasons for using arc/circular tracks.

1/ Form factor - routing a trace around circular fixtures
2/ inductors - personal use was for 13.56Mhz RFID tag
3/ rotary switch contacts

Revision history for this message
Brian Neltner (neltnerb) wrote :

Without this tool it is challenging to route impedance controlled traces -- and even more difficult to route differential pairs of impedance controlled traces (e.g. USB). I need them to curve gently enough to not radiate at corners, to be similar enough in length to work properly, and to maintain distance from one another to achieve a specified impedance.

Usually in EagleCAD I would simply route them as a differential trace after configuring the netlist rules to space them the correct distance from each other and the neighboring ground plane, I'm not sure where I'd even start if I had to route them as a collection of line segments.

Seth Hillbrand (sethh)
Changed in kicad:
assignee: Seth Hillbrand (sethh) → nobody
importance: Wishlist → Unknown
status: In Progress → Unknown
Revision history for this message
Qingliang Yi (niqingliang2003) wrote :

in progress -> unknown????

what's wrong?

Revision history for this message
Jeff Young (jeyjey) wrote :

We moved to GitLab nearly 2 years ago. The recent updates are just to close the bugs out here on LaunchPad because people keep commenting on them (and the dev team isn't looking at Launchpad).

https://gitlab.com/kicad/code/kicad/-/issues/2023

Changed in kicad:
status: Unknown → Fix Released
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