PCB newbie Q on copper islands

Log in or register to post comments
Go To Last Post
16 posts / 0 new
Author
Message
stevech
stevech's picture
Level: Raving Lunatic
Joined: Tue. Dec 18, 2001
Posts: 6119 View posts
#1
Posted by stevech: Sat. Aug 21, 2010 - 02:07 AM
  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

My second spin of a PCB I designed. I read about copper islands and kind of watched out for this. But my new boards have one flaw, where one region of copper fill (pour) became disconnected with ground. It was because a change I made, adding a via, caused that fill region to get isolated from ground due to a too-small area around the via. On my monitor, it is a very small sliver of copper left; in etching, it's an open circuit. Simple jumper wire fixes.

I might have caught this, using freeware expressPCB, had I clicked on the thing to highlight all pins in a net (ground) and had I noted that one pad, tied to ground, did not highlight as a member of the ground net.

Do costly professional packages find copper islands? To do so, it would have had to note that the sliver of copper was too small to assure etching wouldn't fail to leave continuity.

Tags:

Learning and Information, General Electronics
Top
ka7ehk
ka7ehk's picture
Level: 10k+ Postman
Joined: Fri. Nov 22, 2002
Posts: 21553 View posts
Location: Tangent, OR, USA
Posted by ka7ehk: Sat. Aug 21, 2010 - 02:41 AM
  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

What layout software did you use?

Jim

 

Until Black Lives Matter, we do not have "All Lives Matter"!

 

 

Top
glitch
glitch's picture
Level: Raving Lunatic
Joined: Sat. Jan 12, 2002
Posts: 8620 View posts
Location: Canada
Posted by glitch: Sat. Aug 21, 2010 - 03:15 AM
  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

yes most good packages will identify copper islands. As for the sliver, good packages won't generate any features thinner than your minimum trace width, or will at least alert you to the existence of a feature that is thinner than the limit.

Writing code is like having sex.... make one little mistake, and you're supporting it for life.

Top
ka7ehk
ka7ehk's picture
Level: 10k+ Postman
Joined: Fri. Nov 22, 2002
Posts: 21553 View posts
Location: Tangent, OR, USA
Posted by ka7ehk: Sat. Aug 21, 2010 - 03:21 AM
  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

I think even Eagle will, if you run a DRC (design rule check) on the layout.

Jim

 

Until Black Lives Matter, we do not have "All Lives Matter"!

 

 

Top
stevech
stevech's picture
Level: Raving Lunatic
Joined: Tue. Dec 18, 2001
Posts: 6119 View posts
Posted by stevech: Sat. Aug 21, 2010 - 09:15 PM
  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

The, er, good software I used for these little 2 x 3 in boards is, er, expressPCB.

To alert, it would have to have trace sliver width checks for less than x. On screen there is continuity; after etching, not so, due to trace width too small. It's at a crowded place with clearance problem created by a via.

Top
ka7ehk
ka7ehk's picture
Level: 10k+ Postman
Joined: Fri. Nov 22, 2002
Posts: 21553 View posts
Location: Tangent, OR, USA
Posted by ka7ehk: Sat. Aug 21, 2010 - 09:18 PM
  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

Eagle WILL do that, pretty sure. Or just not draw it, in t he first place. Never had any problems with this and I've given it plenty of chances.

Jim

PS - I am not saying that Eagle is good. There are lots of things in the user interface that drive me ... (further than I already am). It just what I've been using so that is the reference I can compare to.

 

Until Black Lives Matter, we do not have "All Lives Matter"!

 

 

Top
nleahcim
nleahcim's picture
Level: Raving Lunatic
Joined: Wed. Feb 19, 2003
Posts: 2191 View posts
Location: Redwood City, CA
Posted by nleahcim: Sat. Aug 21, 2010 - 11:02 PM
  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

Eagle will catch that with a DRC. Altium Designer will catch it as well.

Top
stevech
stevech's picture
Level: Raving Lunatic
Joined: Tue. Dec 18, 2001
Posts: 6119 View posts
Posted by stevech: Sun. Aug 22, 2010 - 06:30 PM
  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

Twice now I've invested several hours with Eagle. Both times I gave up due to the less than horrible UI.

So for expediency I used expressPCB. Of those I tried, DipTrace looked best, but learning time was too long vs the project's schedule.

Do the pro level PCB tools warn that there's a possible copper island because somewhere in the pour area there's a sliver that might disappear in etching? Doing so breaks electrical continuity to the ground plane.

Top
leon_heller
leon_heller's picture
Level: Raving Lunatic
Joined: Fri. Jul 27, 2001
Posts: 7672 View posts
Location: St. Leonards-on-Sea (UK)
Posted by leon_heller: Sun. Aug 22, 2010 - 06:48 PM
  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

Most have a setting for minimum copper width, so the problem shouldn't arise. There are programs that are used by some board manufacturers that check the Gerbers for that sort of thing, as well as copper slivers that might work loose and cause a short.

Leon Heller G1HSM

Top
nleahcim
nleahcim's picture
Level: Raving Lunatic
Joined: Wed. Feb 19, 2003
Posts: 2191 View posts
Location: Redwood City, CA
Posted by nleahcim: Sun. Aug 22, 2010 - 07:05 PM
  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

stevech wrote:
Twice now I've invested several hours with Eagle. Both times I gave up due to the less than horrible UI.

So for expediency I used expressPCB. Of those I tried, DipTrace looked best, but learning time was too long vs the project's schedule.

Do the pro level PCB tools warn that there's a possible copper island because somewhere in the pour area there's a sliver that might disappear in etching? Doing so breaks electrical continuity to the ground plane.


Yes. That is a standard DRC rule. I haven't used Eagle for a number of years now, but I suspect even Eagle checks for that. I could be wrong though - I was never very impressed with that package. (you get what you pay for!)

Top
curtvm
curtvm's picture
Level: Raving Lunatic
Joined: Wed. Sep 21, 2005
Posts: 3056 View posts
Posted by curtvm: Sun. Aug 22, 2010 - 07:43 PM
  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

DipTrace will do what you want with copper pours, and is about as easy as it gets. It has island removal and clearance options that should handle most situations, I would guess.

It seems to me that DipTrace has about as normal an interface as you can get with pcb software, and you won't be struggling with the user interface. I think its almost as easy to use an ExpressPCB.

In addition to the normal user interface, I like the 'pin limit' way of restricting the free version vs limiting board size in Eagle.

/advertisementover

Top
alank2
alank2's picture
Level: Raving Lunatic
Joined: Thu. Jul 16, 2009
Posts: 3000 View posts
Posted by alank2: Mon. Aug 23, 2010 - 12:55 AM
  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

Hi,

I also use expresspcb and manually check for ungrounded islands. See my thread here:

https://www.avrfreaks.net/index.p...

Page 2 I have sort of a checklist I go through to design a PCB, I'm not sure if it will help, but you might take a look at it.

Thanks,

Alan

Autoprogrammer:

https://www.avrfreaks.net/forum/wts-standalone-pdiisp-auto-programmers

Top
stevech
stevech's picture
Level: Raving Lunatic
Joined: Tue. Dec 18, 2001
Posts: 6119 View posts
Posted by stevech: Tue. Aug 24, 2010 - 04:12 AM
  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

Thank you all, esp. Alank2 for the thread pointer.

I think I'll try DipTrace for my next boards. The time I spent with it indicated that it was the best of the 4 or so I tried (as a novice).

Top
alank2
alank2's picture
Level: Raving Lunatic
Joined: Thu. Jul 16, 2009
Posts: 3000 View posts
Posted by alank2: Tue. Aug 24, 2010 - 12:11 PM
  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

Hi,

I too have been trying my luck at DipTrace. It looks like it has a lot of features.

Thanks,

Alan

Autoprogrammer:

https://www.avrfreaks.net/forum/wts-standalone-pdiisp-auto-programmers

Top
alank2
alank2's picture
Level: Raving Lunatic
Joined: Thu. Jul 16, 2009
Posts: 3000 View posts
Posted by alank2: Tue. Sep 21, 2010 - 01:02 PM
  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

Hi,

Well, I had diptrace crash on me a couple of times and since the "Eagle" is so strong I decided to really give it a game effort to learn. It took me about 4 evenings work, but I finally got it figured out and converted one of my expresspcb boards to eagle. I have to say that I am quite pleased with Eagle now that I've been working with it. Their forum was helpful in answering questions. I agree their UI is a bit backwards, but once figured out it isn't too bad. Their pour handling is excellent however - it won't create ungrounded orphans unless you tell it to. It also creates a smooth flowing pour without all the jagged edges that expresspcb creates that you must manually go back through and exclude. I am quite pleased to have made the transition and it was less painful than I thought it would be.

Good luck,

Alan

Autoprogrammer:

https://www.avrfreaks.net/forum/wts-standalone-pdiisp-auto-programmers

Top
devils4ever
devils4ever's picture
Level: Hangaround
Joined: Mon. Sep 11, 2006
Posts: 131 View posts
Location: New Jersey, USA
Posted by devils4ever: Wed. Sep 22, 2010 - 01:01 AM
  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

I'm using Kicad for schematic capture and PCB layout. So far, I'm very impressed with it. It won't let you route traces over other traces or violate minimum clearances. It's a little tricky getting used to using it. But, all PCB software is quirky. Kicad is free for both commercial and private use.

Top