Rounded corner track discussion

I realize all the cool kids are doing it, but running a risk of sounding like a Debbie Downer I would like to ask - why? This RF superstition was debunked years ago (here for example) I’m all for additional bells and whistles in KiCad but when we don’t even have basic features available, like PCB penalizing, I think catering to all those 3 people who work with microwave design in KiCad might be a bit … excessive?

  1. Flexi card design - this is a must
  2. high voltage design - not as critical as #1 but sharp corners are a no-no

Considering etching doesn’t make sharp corners anyway and there are use-cases where it is beneficial … Why not. It’s like placing a BGA at 45deg, it does help with tracking a bit BUT it’s an eye grabber mainly

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My mistake. Now we are catering to all those 4 people if you factor in those who do high voltage design in KiCad :slight_smile:

45 degree corners work just fine on flexible PCB, and again, the demographics of KiCad users designing flex circuits is somewhat limited.

I’m not against esthetics, but I think it might be a bit prematurely to detail a car when the transmission is still shifting only into two gears.

Right now KiCad is having heavily refactored foundations, and not added bells and whistles.
This step is needed to support advanced features in future releases, without having to build upon dirty workarounds.
I’m test driving 5.99 for some time, and IMO it’s many small improvements built on refreshed foundations. So no point in complaining that this or that feature is not supported [now].
I’d rather have the 6.0 released within reasonable timeframe, than having “best Kicad ever” vaporware which would be always under construction.


Just out of curiosity, which advance features a going to include tracks with rounded corners?

Again, I’m not against advanced features and I realize that no matter what you do there always be somebody wanting some other feature done fist. However I’m also a fan of getting the basic features done first before you start talking about advanced ones.

AFAIK these were necessary for the importers (Altium).
Typically they’re used in some RF designs. Since general purpose radios (Bluetooth, Wifi) is already Microwave, proper use of these should be considered good design practice.

And right now it’s important for the pcb geometry, file format to handle these (foundations). High-level features will come second.


This thread is meant for announcements and news, not commenting on features, please move this conversation to a separate topic, my email is getting bombarded.


Cloning hand drawn boards is another use case

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Another use-case is naysayers

“Kicad cannot be taken seriously because I cannot do foo”

It is inconsequential whether the majority would not find an engineering need for the capability if the majority of non-users dismiss kicad based upon the lack of said capability.
Likewise importing projects from eCAD tools that do support curve tracks will not work if it cannot be mapped into kicad

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45 degree corners work just fine on flexible PCB, and again, the demographics of KiCad users designing flex circuits is somewhat limited.

Whether or not they are fine in your opinion, there is a lot of guidance out there recommending that people avoid sharp corners on flex circuits, especially dynamically-flexing ones.

It doesn’t really matter how true this is or how important it is: as long as lots of PCB manufacturers and others are giving this advice, people designing flex circuits will demand it of their layout tool.

But putting this specific point aside, I think the main argument I have is with your general premise:

the demographics of KiCad users designing flex circuits is somewhat limited.

Our mission is to expand the demographics of KiCad users. KiCad is not supposed to be the “hobbyist option”, suitable only for the 80% of use cases that don’t need advanced techniques – it is supposed to be a fully-featured tool for professionals. We want more people designing RF, high-voltage, and flex circuits in KiCad.

We know that one reason KiCad doesn’t have as many people doing that type of design work is that we are missing features that those users find important. So, we are working to add those features. Whether or not you personally find routing with curved corners important, it’s something that we hear requested frequently, which means that it’s a reason some people decide not to use KiCad.


For what it is worth - I am one of those users interested in getting curved tracks in v6 and am actively working on improving KiCad’s support of it because it is important for me.

I consider it quite a basic feature and it would be difficult to convince my colleagues to switch to KiCad if this wasn’t supported - almost all of the designs in my company have at least one track that is curved. The CADSTAR importer would have had to approximate curved tracks with piecewise linear segments which would make them uneditable.

Also, RF and flex boards are not the only reasons for curved tracks: ease of layout in circular/round shaped PCBs is another that comes to mind as well as possibly increasing routing density in some scenarios.

I am not sure what “basic” feature you are missing, but if it is really important for you can develop it yourself or pay a developer to develop it for you to meet your timeline. KiCad Services have very competitive pricing for these requests - I can thoroughly recommend them.


PCB Panelization was mentioned as a “basic feature”, but in the developer’s point of view, it is not: it’s quite advanced and complex to do panelization correctly – meaning including all the necessary DRC checks for manufacturability, switching between editing the board and editing its panel layout, etc.

Typically in volume production this is handled by an entirely different software stack that works on Gerbers or other manufacturing outputs. Some PCB design tools include panelization, but in many cases panel design for a given PCB is “outsourced” to a different part of the production pipeline, as the PCB designer knows what is best for a PCB but normally not what is best for a panel – that is the job of a manufacturing engineer supporting the fabrication line. Yes, I know there are exceptions to this, you don’t have to tell me :slight_smile:

We balance every feature request between the cost to implement (how much time will this eat up? what other changes would be required to even make it possible? what will get delayed in order to prioritize this feature?) and the benefits (how many users will be able to use KiCad who were not able to use it before? how many existing KiCad users will have a better workflow?)

If the feature has a very high cost (panelization certainly does) the benefit question becomes a lot more important.

This is different than the RF stuff where corners may be or are important only in the high end of the spectrum, and possibly not everywhere where they have been used. Mechanically every corner matters because a physical object, when it is bent, always breaks in the weakest spot first, and all inner corners are weak spots.

It’s even so that a thinner trace (or other object) is stronger than an othewise wider one that has a weak spot, even when the weak spot is itself wider than the thinner trace. That’s a law of physics, and it’s practical, not just theoretical.

Of course if a flex board is bent once and there’s no vibration later it doesn’t matter much.


PCB panelization is of interest to people who make their own PCBs from scratch.
For most of us it would conflict with the CAM tools used by the PCB fab, to get minimum waste of their blanks

Needs for a certain panelization for assembly reasons can always be solved by direct communication with the PCB fab

Planar transformer. I did the transformers in Eagle CAD because I know how.
In another design I needed one turn per layer. Red = one turn.
My last hand full of designs I used the foot print editor to make rounded traces. Not good.
Now 5 people that would use rounded traces.


The post title “…discussion” implies “discussion, not ‘Announcements and News”

Having Patents on medical connectors - one for use with Flex Circuit, peaks my interest, I thus add the below screenshots of p13, p14 from ‘Flex Circuits Design Guide’ from

The full document is worth a review for those designing Flex Circuits… Of particular interest to references in the above posts on Corners. Also, good insightful tips on capturing/holding down Pads (if you make/tweak footprints…)

The thread was split to a new topic.

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Got it… Thanks.

While here, I’ll finish-up re Curved Tracks with following image…

(fyi - re method 1, draw trace/track on different layer because cannot attach to what it
thinks is a filled zone. Note: I did not fuss with making precise geometry/dim’s)

That looks gorgeous.
last one I worked with I used 45deg traces to make the loops - 12 layers

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I think there must be at least six of us who are using rounded tracks in recent projects …

Screenshot 2021-01-02 at 22.27.25

Screenshot 2021-01-02 at 22.29.41