Octagonal (not round) clearance around vias.

[odinrizhanin]

Hi,
Is it possible somehow to make copper shape around vias not octagonal but round (or have more sides)?.

Explanatory image in attachment.

[Yura.Ivanov.VLuki]

Hi,

octagonal copper shape around vias at you in settings.

Remember that you changed at yourself in settings.

[odinrizhanin]

Юрий, добрый день!
Thank you for response, I have found only how to change the shape of PAD, not of the copper around it.

I believe, if you reduce via drill to 0.2mm, you will have the same issue as me - the copper around round via will be in shape of octagon.

So, the problem is still not solved.

[Yura.Ivanov.VLuki]

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@odinrizhanin wrote:

I believe, if you reduce via drill to 0.2mm, you will have the same issue as me - the copper around round via will be in shape of octagon.

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no problem

[Yura.Ivanov.VLuki]

Attachments

[odinrizhanin]

Thank you for board file! 🙂
This helped to understand, that issue is somewhere in Eagle's global settings or DRC file (not VIAs settings), because when I open your board file on my PC, everything looks like it should - copper layer around 0.2mm round via is round too...

When I go back to my design, with same VIA settings, problem exists.

Going to search this settings

[one-of-the-robs]

I'm not at a machine with Eagle to check this but I think the clearance round a circular via is drawn as a series of straight lines approximating a circle, and that the length of those lines depends on the "width" parameter of the polygon. If you want near-circular rings round very small vias, you need to use a "narrow" polygon.

[Yura.Ivanov.VLuki]

No.

With settings of a polygon, I cannot receive octagonal openings.

Попробуйте загрузить DRC (default), and (or) NET Class (default).

Remember (where was and with whom). 😉

Good luck.

[Yura.Ivanov.VLuki]

IMHO, look at settings

[iquacker]

The answer is how thick the lines are that form the polygon. On the left, the polygon line width is 0.2mm, on the right it is 0.1mm. The second picture shows the same thing but with the layer specified as a hatch rather than a solid. This makes the effect a bit easier to see. I have not done any work to see if these widths hold true globally or if they are related to the pad size of the via - which in this case is .7mm

Regards -

[Yura.Ivanov.VLuki]

Hi from Russia!

And maybe, that you had oktogonalny transitional openings earlier?
Did you set them?
Try to delete a polygon and to make rollback.
Good luck!

[Yura.Ivanov.VLuki]

1. We put Vias, we draw a Poligon.

2. We change a form of Vias.

3. We delete a polygon and we do rollback, (Ctrl+Z).

[odinrizhanin]

Hi guys!

Привет из Риги 🙂
@Yura.Ivanov.VLuki  , @iquacker  thank you for attempts to recreate a problem.
In my case I tried all following:

1) changed width of polygon down to ZERO mil. (every time pressing command "RATSNEST" to recalculate polygon)

2) tried to assign different NET classes to signal of polygo

3) Change "Shapes" tab in DRC (I believe, it's only for PADs, not VIAs)

all points didn't help 😞  @one-of-the-robs  could this be officially considered as bug?? - image attached + board file attached.

[hudriwudri]

I just experimented a bit with your brd file, and I think it's a bug, but a very concealed one. And an old one too, Eagle 7.7 behaves the same. The issue arises when width and isolate are both very small. If you make one of them sufficiently large, you get a (nearly) round cutout.

For example with your brd file, the issue is still there when width=14mil and vanishes when width=15mil (and the resulting isolate value from DRC/netclass = 5mil).

So I suspect the problem is a rounding error in an intermediate calculation result in the program. Increasing the precision (float to double) or changing the sequence of math operations (multiplication before division) might already cure it.

[Yura.Ivanov.VLuki]

Yes, at values less than 9 mil, all octagonal become

[iquacker]

Meanwhile...

I do lots of very tight 4 layer boards with 4/4 and even 3/3 copper and have never found octagonal setbacks to be a problem, so I never tried to fix it until last night, just to see if I could.

Regards - 

[iquacker]

Making the line width bigger, makes the setback go round.

[Yura.Ivanov.VLuki]

The nature does not suffer direct lines, the computer cannot take ripples in the water.
Draw hands!

Good luck!

[odinrizhanin]

@one-of-the-robs , could be this fixed in next version of Eagle? - it's quite unpleasant, that I can't set width and clearance of polygon I want without getting a bug mentioned in the topic.

[one-of-the-robs]

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@odinrizhanin wrote:

@one-of-the-robs , could be this fixed in next version of Eagle? - it's quite unpleasant, that I can't set width and clearance of polygon I want without getting a bug mentioned in the topic.

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I fear you have completely misidentified me. I am not an employee of Autodesk, nor in any other way an official representative. I am merely a user, like yourself, albeit with a good few years' experience and a tendency to post too much on forums.