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Having trouble getting a track width design rule priority to be dominant

miner_tom , 12-14-2018, 09:19 AM

I have set a design rule for Routing Width of the GND and power nets called "Width Power". I have also set the priority of that design rule to be "1" while the remaining design rule "Width" is "2". However, the "Width Power" design rule is not dominant. I can see this when I route a track from one of the nets in the new design rule, called, for example GND. I still see that the net is a width of 0.2mm not 0.3mm as would be the case if "Width Power" design rule were dominant. The only way that I can get "Width Power" to be dominant is to Disable the "Width" design rule.

Attached is a screen shot of my Rules and Constraints editor.

Thank You
Tom

mairomaster , 12-17-2018, 01:50 AM

Most probably your rule works fine. The problem might be with Altium not picking the preferred value for the particular net. This is really messed up with Altium 18 to the extent that you should always pay attention to the width that is selected when routing a track. The upside is that the DRC will catch everything that is outside the Min/Max limits for the nets.

robertferanec , 12-17-2018, 04:49 AM

I do not use this option to control track width by Altium. I tried that couple of times in previous AD versions, never worked well. I have not played with it in AD18 yet, but good to know, that it looks broken. PS: Mostly I use only a very few different widths in the initial phase of layout (saves a lot of time). After everything is connected, usually only then I adjust track width.

miner_tom , 12-17-2018, 10:07 AM

Robert,

I think that this is one additional "feature" than one needs to be aware of in 18. In "Preferences->PCB Editor->Interactive Routing->Interactive routing Width Sources" you can see that there is a way to select rules or override rules for Track Width or Via Size. It was tough to find this one.

One additional comment concerning the video #2: When you demonstrated setting up the design rule for "Width Power" you set up a preferred track width of 0.3mm. Later on in the video, it was clear that the preferred track width, under the BGA was 0.4mm. Did you change the default rule to 0.4mm or did you override the default when creating the track and then do a copy paste?

Thank You again for wonderful videos.

Tom

robertferanec , 12-18-2018, 05:16 AM

In "Preferences->PCB Editor->Interactive Routing->Interactive routing Width Sources" you can see that there is a way to select rules or override rules for Track Width or Via Size. It was tough to find this one.

- they moved it to preferences, but that setting also exists in previous AD versions - that is the setting what didn't work well for me. Maybe they fixed it now (?)

One additional comment concerning the video #2: When you demonstrated setting up the design rule for "Width Power" you set up a preferred track width of 0.3mm. Later on in the video, it was clear that the preferred track width, under the BGA was 0.4mm. Did you change the default rule to 0.4mm or did you override the default when creating the track and then do a copy paste?

- Please, to what video and what minute are you referring to?

miner_tom , 12-18-2018, 08:46 AM

Hi Robert,

I have attached three screen shots from the second video in the advanced layout series. Times are 14.39, where the Width Power rule is set to 0.3mm. One at 20.25 where a power track is laid out which is clearly not 0.3mm. One at 20.03 which actually shows the rule set at 0.4mm.

I found it somewhat confusing. You said a bit after the last screen shot that you like to route 0.4mm power traces under the BGA.

Regards
Tom