1
\$\begingroup\$

Im using some thin traces in certain areas of the board that I want to have beefed up with a polygon pour. However, when I run the rule check it just ignores that the width of the traces is now effectively larger due to the pour, and still reports that they don't meet the minimum width. Is there a way to change some of the rules so that it doesn't do this?

enter image description here

Here's a picture for reference. The wire inside the black rectangle highlighted green due to breaking a rule is of the same net as the polygon surrounding it.

\$\endgroup\$
2
  • \$\begingroup\$ Can you post a picture of that section of the board? \$\endgroup\$
    – Armandas
    Sep 3, 2014 at 7:53
  • \$\begingroup\$ Looks like the small polygon doesn't have a net attached? \$\endgroup\$
    – Dejvid_no1
    Sep 3, 2014 at 8:54

4 Answers 4

3
\$\begingroup\$

Fundamentally, polygons are evaluated separately in the DRC system.

Traces are traces, and polygons are polygons. The DRC system for checking trace width runs effectively with the polygons all shelved.

Realistically, when would you ever want to have traces that violate the design rules? If they're embedded in a polygon to the point where their width is irrelevant, you can delete them. If they're not embedded in a polygon to the point that their width is irrelevant, their width is relevant.

You're doing something that does not make sense, and the DRC doesn't account for it because there is no reason to do what you are doing.

\$\endgroup\$
1
\$\begingroup\$

What's the meaning of having wires betwen pads when you intend to put polygon pour between theses pads. Remove these non functionnal wires.

\$\endgroup\$
0
\$\begingroup\$

I would be careful with using this method of PCB layout, it is likely false economy.

Why are you using thinner tracks than you need? If the correct sized track is too wide to route properly, then a polygon pour will not improve matters.

Personally, I prefer to route ALL tracks with at least the minimum width, then "bulk up" with polygons. Necking down is an option if you wish to retain smaller thermal reliefs for pads. It's the best of both worlds, as it allows you to use both the track rules and polygon rules to assist with design verification.

This allows the DRC to use the minimum width rules correctly, and ensures a sneaky polygon doesn't form a tiny, tiny connection, and say that everything is fine.

\$\endgroup\$
0
\$\begingroup\$

Polygons and tracks are used in very different ways. If the DRC considered the additional copper added by the polygon when evaluating the track width, I would be very disappointed.

My advice would be to change how you have set up your routing. If you want width checked by the DRC, then use a correctly sized track. That doesn't mean you can't use a polygon on top of that to add a little extra copper around vias and other obstacles (design dependent), but the track is necessary.

Alternatively, if you don't need the width to be checked, you can use a polygon to do the bulk of the work with either no tracks or any width tracks, but I would normally steer towards having the routing checked by the DRC. This is still design dependent as polygons can help you deliver high power to components while getting around tonnes of vias spearing the board.

Note: Anywhere I've said "polygons", the same also applies to fills and regions.

\$\endgroup\$

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.