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How do I create a void in a power plane?

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I want to remove an area of copper from a power plane but can't work out how to do this.
 
I'm sure it's obvious if you know how!
 
Please could a kind soul point me in the right direction?
 
Thanks
Dave
 
 
 
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Message 1 of 14
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Hi Dave:

You can use a keep-in/out area to create a void in a power plane. You will probably need to play with the Layer/Advanced options to get the DRC rules correct (it depends on exactly what you are trying to do).
Garret
Senior Software Developer
National Instruments
Circuit Design Community and Blog

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Message 2 of 14
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It seems like you could also draw around the area you want with a trace, then use the Remove Island tool to clear out the inside. 🙂
____
Ryan R.
R&D
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Message 3 of 14
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In this case I don't think a "keep out area" will do the trick, as I want to put some other stuff in there.   Adding a track and using remove island did what I wanted, but it seems an untidy way to do things.   I'd have expected to be able to select an area on the plane and just delete that, but couldn't find a way to do it hence the question.

Thanks for the help.
Dave
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Message 4 of 14
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Well the "tidy" way would be to put in a keep-out area after your parts are placed, ignoring the DRC errors, THEN add the power plane. After the plane is drawn you should be able to remove the keep-out area and touch up as necessary.
____
Ryan R.
R&D
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Message 5 of 14
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You can still use a keep out area (this is what is was referring to with setting up advanced options). You need to create a keep-out area that will only exclude then net associated with the power plane.

First assign the net that has a power plane to a net group in the group editor (Tools > Group Editor). Then, change to the keep-in/keep out layer in the Design Toolbox, and double click on the keep-in/keep-out area. In the Advanced options, check Net Group, click Options, uncheck All Groups (at the bottom) and ensure only the group you just created is checked.

The keep-out area will now keep out only the net group. You can have other things in the keep-out area, without causing DRC errors.

Note: You can also access the keep-in/out area properties from the spreadsheet keep-ins/keep-outs tab.

.


Message Edited by koekje on 07-09-2008 01:14 PM
Garret
Senior Software Developer
National Instruments
Circuit Design Community and Blog

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Message 6 of 14
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AFAICT the approach of using a "keep out" works when you know in advance of placing the power plane that you want to make a hole in it, and where.

All that seems to happen if you place a keep out after the event is that you get a DRC telling you that the keep out has stuff in it that shouldn't be there.

So the track and delete island seems the way to go.

Unless of course ...

Cheers, Dave

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Message 7 of 14
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Hi Dave,

why dont you use the poligon splitter option of UB. You can splitt the plane and delete the unneeded part of the plane.

Greetings from germany

GP

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Message 8 of 14
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Hi David:

If the delete island way works, that's great.  Still, I think I'm either not explaining my solution correctly or understanding the problem you're describing. Even if it doesn't help you, it might help others, so I'll describe with an example.

The example I'm describing is attached below.

There are three nets (GND, 1, and 2) in the example, and two parts. The two parts are connected by nets 1 and 2 and GND is assigned to the power plane. Once I placed the power plane, I setup the groups and keep out to create the void.

1. Place > Keep-in/Keep-out Area. Draw the area where you want the void. You will have DRC errors at this point, and we will now remove them.
2. We need to assign the net GND to a net group so it can be associated with the Keep-out area. Tools > Group Editor. On the Net Groups tab, click Add, and create a new group GROUP_GND. Then assign only net GND to the group.
3. Select the Keep-in/keep-out layer in the design toolbox. (The selection filter can be set to Enable Selecting Other Objects). Select the Keep-out area, then Edit > Properties. The Keep-in/keep-out properties should show. On the Keep-in/keep-out tab, check the box next to Net Group. Then click the Options... button beside Net Group. Uncheck All Groups at the bottom, and check GROUP_GND. Click OK, click OK.
4. The DRC errors should be gone because the keep-out only applies to net group GROUP_GND.

I hope this explanation clears up my ambiguity from before, even if it doesn't help in the end. Smiley Happy
Garret
Senior Software Developer
National Instruments
Circuit Design Community and Blog

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Message 9 of 14
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Dave,

I've confirmed that Garret's method works wonderfully, and is less complicated than the trace and remove island method. The main thing is that the keep-out layer will make the power plane not draw there, but will not remove anything else. 🙂

____
Ryan R.
R&D
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Message 10 of 14
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