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I would like to know if is it possible to build up a rule that treats a single net in different way.

I have some circuits in which some nets needs to be dimensioned for high current. So I create a net class and I assign to that net class the desired width. So far, so good.

The problem is that not all tracks of that net need to this width for high current (for example think about parallel components). So I would like to make a rule that makes the net bigger only where it needs.

Is it possible?

I've tried with some rules but without any result: I made the Net Class with all net for high current and then a Component Class with all and only the component connected to high current wire. I make this rule: InNetClass('HC') AND InComponentClass('HC')... but obviously it doesn't work because the nets of class HC belongs also to component outside class HC.

How can I solve this?

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  • \$\begingroup\$ I am not sure if I understand what you want to achieve, but I don't think it is possible. A NET is a NET. There is no way to treat different wire segments of a net separately using the design rules (except by surrounding specific segments/parts of the net with rooms, but then you could obviously just route those segments manually in the first place). \$\endgroup\$
    – Rev
    Aug 3, 2015 at 16:38
  • \$\begingroup\$ PS: You may want to post a picture with an example. \$\endgroup\$
    – Rev
    Aug 3, 2015 at 16:39
  • \$\begingroup\$ Easiest thing would be to set the minimum, preferred, and maximum width rules so that "preferred" is the smaller width for that net, and "maximum" is the high-current trace width. Then you manually change the width of the high-current traces to the maximum width. Leave the low-current traces at their minimum (or preferred) widths. \$\endgroup\$
    – DerStrom8
    Aug 3, 2015 at 18:20
  • \$\begingroup\$ Thanks. I was afraid it wasn't possible..and you confirm it. I use the technique derstrom suggested. I think it's the only way. Thank you all. \$\endgroup\$
    – Gianluca Suzzi
    Aug 3, 2015 at 20:22
  • \$\begingroup\$ Maybe you can make a new component that is just a single SMD pad or two overlapped pads (I don't know). Then you could split the net into 2 nets and apply the rules separately. \$\endgroup\$
    – Justin
    Aug 3, 2015 at 20:55

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Maybe you can add to your net-rule a room. So only the net within this certain room needs to have the bigger width (InNet('') and InRoom('') or similar).

You can also set this in the schematic. I have seen this but i don't know how to do this. Its a rectangle around the nets which specifies the needs for them.

My experience showed that it's easier to set this manually than with such specific rules. If it's just a small pcb I think then it's not worth it dealing with complicated time consuming rule settings.

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  • \$\begingroup\$ Yes, I was thinking about that but as you say I don't want to mess the sch with fake net only to achieve this goal. I think I'll do it manually ;-) tank you anyway \$\endgroup\$
    – Gianluca Suzzi
    Aug 4, 2015 at 6:54

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