Copper layer priority, fault in the layers.

[stressed_user]

Hi all,

First of all, I need to say that I'm using version 10.1...

When adding a copper area on a board, and assigning it to a net, all works perfectly.

When adding a second copper area (with a different net) close to it (or even overlapping), one of the two layers will have to push the other...

But which one has priority, or how is it decided?

Why this question?

This happened on a large board that I designed:

I had multiple copper area's  used to widen tracks for high current.

At the end of the board layout I added ground copper area over the power side of the board. (not the complete board)

The attachment shows what happened:

-the track connecting the via's to the U2 pad is visible (net called FDSUP) and connected.

-You can also see the selected copper area connecting both (and it is connected to FDSUP net) (yellow dotted line)

-But the coppera rea is not attached to it (even not after an extra manual DRC check)

When I move the ground copper area that lies above it, the copper area to net FDSUP reappears!

To show you, I moved it halfway, and as you can see half of the copper area is connected...

The bottom half is still covered by the ground cooper area!

Why did this happen on this (FDSUP) copper area and not on the many other copper area's on the same board?

Is there a way to give one a priority?

I tried making a new area for the tab of U2 and connecting that to the FDSUP net but that one dissapeared as well..

So it is not a question of which was put first or last...

So what is the rule behind it? How to control it?

Stressed as usual...

[stressed_user]

Hi,

I guess everyone is on holiday?

Or was the question not clear enough?

[Tom-S]

Hi stressed_user,

I'm one the applications engineers at NI. I've started looking into your question, but before I look into this further I need check that this is still an issue for you and you haven't managed to solve your query?

Kind Regards,

TomS

Applications Engineer

National Instruments

[stressed_user]

Hi Tom,

No, this issue is still not solved.

Thans for looking at it...

[Tom-S]

Hi Stressed_user,

I've located this KnowledgeBase article about routing a net on a specific copper layer which may help you:

http://digital.ni.com/public.nsf/allkb/A1D3136F210607DE862572040065305A

If I have misunderstood your issue, could please clarify for me?

Kind Regards,

Tom Shelley

Applications Engineer

National Instruments

[stressed_user]

Hi Tom,

No , this is not my problem, the article in the knowledge database is about putting area's in a limited numer of layers...

My problem is only happening with two copper area's connected to a different net, on the same layer.

you can see that in the screenshots I posted:

-On the green layer I have a first copper area connected to a net called FDSUP

-afterwards i put extra layer on the ground net (net 0) covering a part of the board.

-That area connected to the 0 net is 'eating' away the area that was put and connected to FDSUP.

-So only the original track is left as you can see.

The question is also, 'Is there a rule?'

because some area's have this problem when covered and others don't..

I can work around it by drawing separate area's drafted around the allready built area's, but that's quite a job...

Usually using a second copper area covering the first one is no problem, i Do it very often...

But on this larger layout, it always gives faults on this copper area... even when all the settings are correct...

stressed user

[stressed_user]

Tom,

i have done a new test of which you can see a sreenshot here.

1) On a blank layout, I added a copper area A connected to net 1

2) then I added a copper area B, connected to net 0, you can see that this area B cuts a part out of A.

3) next I add an area C which I connect to net 1 as well, this area cuts a part out of area B

-so area A and C are both connected to net 1 but act differently towards area B, connected to net 0.

I  have a feeling that there is some kind of 'time stamp' relation towards it.

Is that possoible? And if yes, is it possible to change that time stamp in order to chnge the priority...

that would mean that the that was put last always will cut out a part of the one that was put first...

that's what this test would suggest...

On the other hand, on my layout, I'm sur I put the area on net 0 last, and it only cuts out some of the area's, not all...

Stressed user...

[Tom-S]

Hi Stressed_user,

Thank you for clarifying, I think I have a better understanding of what you are trying to acheive now. I've tried to recreate the situation in the screenshot you attached.

I'm using Ultiboard 13.0 so im not sure if this feature is on 10.1, but have you tried using the 'Voiding' property? By default this is set to 'Yes' but setting this to 'No' should stop the copper areas cutting off others. Voiding is used to prevent short-circuits between copper areas, and when enabled a space is drawn between objects that would otherwise be touching. If multiple objects are set to void, then as you said, it looks as if this is based on a timestamp of when they were placed. However, I found that by adjusting this property I could get the board to behave as you wanted.

Let me know how you get on,

Kind Regards,

TomS

Applications Engineering

National Instruments

[stressed_user]

Tom,

Disbaling the voiding doesn't really help me out. 

All area's stick together making shorts, and giving DRC errors.

When I try this on the original design, it seemed to work at first, since there was no short.

But in fact the ground area (0) was voiding the via's and traces underneath the copper area.

When I removed some of these, I immediately got a DRC error.... shorts betwee the two area's

So switching of the voiding won't help me out here...

If needing to play with these properties, it doens't  give me a correct feeling about the layout.
but I'm happy to see you als had the 'time stamp' feeling...

[Tom-S]

Hi stressed_user,

I've had a word with a few people, and the general consensus is that you cant control the priority of the copper areas - It seems to be controlled directly by the order in which you place the copper areas. 

I'm sorry that I can't be of more help, but Ultiboard is one of our lesser used programs, and within the UK office we dont have any experts. As this forum post has had a lot of activity, hopefully it will be noticied by someone who may have a solution. If you have an active copy of any National Instruments software, you will be entitled to our standard support program where we can escalate specialist requests such as this. If so, a service request can be made by logging into MyNI. 

Kind Regards,

Tom-S

Applications Engineering

National Instruments