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 Two Layer Board with copper fill on top and bottom; Problems with Void touching Shape 

Last post Wed, Jul 31 2013 7:28 PM by NelsonsTrfgr. 10 replies.
Started by NelsonsTrfgr 17 Jul 2013 06:37 PM. Topic has 10 replies and 1552 views
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  • Wed, Jul 17 2013 6:37 PM

    Two Layer Board with copper fill on top and bottom; Problems with Void touching Shape Reply

    Allegro 16.3. I have created a simple two layer board with copper fill on top and bottom. This copper fill is my ground plane. I followed a manual that explained how to create the shape, assign a net name and create voids. Everything seems ok, I have several SMT footprints and through hole parts and several vias installed on the board. When I do the update DRC, it returns with no DRC errors detected. When I go to produce the artwork, I choose RS274x, select all films and create artwork. It returns an error:

     ERROR: aborting film - Shape with first seg=(841.447 1910.321) [layer=TOP]
     has a void with extents [(1771.492 748.691) (2223.750 978.392)] that touches
     another shape with first seg=(25.000 25.000). Manually resolve problem.

    I followed several of the posts on this forum to attempt to resolve this issue. I moved the entire ground fill (on the top only) away from all other components. This solved the problem. I can get the artwork with no errors. When I try to pin point the offending part, it seems every part on the board will cause the error above. I selected the "Global Dynamic Shape Parameters" menu and set the minimum aperture for gap to 500 mils, along with teh suppress shapes less than 500 mils. This solves the problem, I can get the artwork with no errors. However, my ground plane has shrunk from a 2 inch x 2 inch plane to about 1/8 inch by 1/8 inch in the lower right corner (this is not acceptable). The bottom ground fill does not have these problems. It also has no SMT parts on the bottom.

    I know this must be a rookie mistake. But, I followed most of the fixes that were suggested on this forum and nothing works. I also tried to merge Shapes, but this does nothing. What am I doing wrong?

    Thanks, Richard

    • Post Points: 35
  • Wed, Jul 17 2013 8:39 PM

    • redwire
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    Re: Two Layer Board with copper fill on top and bottom; Problems with Void touching Shape Reply

    These kinds of questions are difficult at best to solve over an open forum -- especially for free.  If you don't mind either (a) posting up your file or (b) sending a copy through email, it would be quicker to solve the problem.  Cadence support will ask for the same thing.

    • Post Points: 20
  • Thu, Jul 18 2013 10:43 PM

    • PRASH36
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    Re: Two Layer Board with copper fill on top and bottom; Problems with Void touching Shape Reply
    Hi,

    Make sure that there is no OUT OF DATE shapes

    Display-->status
    • Post Points: 5
  • Fri, Jul 19 2013 12:32 PM

    Re: Two Layer Board with copper fill on top and bottom; Problems with Void touching Shape Reply

    Hi, I have attached my allegro project, footprints, pads, etc... I still have not solved this problem. One thing I forgot to mention is I used a previous allegro *.brd project that was based on mils. However, I have tried to create artwork with millimeters. Is it possible this could be a problem?

    Thanks, Richard

     

    • Post Points: 20
  • Fri, Jul 19 2013 6:37 PM

    • redwire
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    Re: Two Layer Board with copper fill on top and bottom; Problems with Void touching Shape Reply

     I re-setup the artwork output and cleared up the errors.  However, I could not just leave the board alone. 

     

    There are a lot of nits on the board so I addressed *some* of them.  I have attached a new zip with the artwork parameter file as well as an adjusted .brd file so you can possibly use some of the changes.  Be aware that the input "50 ohm" microstrip is not 50 ohms...  There are a lot of little placement changes that could save you some vias...  Also you still need to finish the silk/assy layers right?  They are mixed up a bit.

     Take a look and if you have any more questions post up.

     

    • Post Points: 20
  • Tue, Jul 23 2013 11:28 AM

    Re: Two Layer Board with copper fill on top and bottom; Problems with Void touching Shape Reply

    Hi Redwire,

     Thank you for all your efforts with helping me with this board. I think I narrowed the problem down to the "INT" layer. If I de-select this layer in the artwork create window, it creates the gerbers without errors. Unfortunately, I don't know what the "INT" layer is for. I looked at the gerbers and all layers are there.

    I can give you some background info. I am an electrical engineer and I typically build the schematic, hand over the netlist to a layout person, wait for the board to show up from the factory, then go into the lab and debug it. My company actually has a layout team. Unfortunately, this project I am working on is a demonstration project. And there is little money for these kinds of projects. I convinced my manager to give me some time to work on this board and a little money to fabricate the boards. But, no money for layout or assembly. So, I figured I could use a previously designed board and just modify it with my new components. The result is what you saw in my zip file.

    Yes, I also need to fix the 50 Ohm microstrip. Thanks for all your help. I will make the changes you suggested and let you know how it goes.

    • Post Points: 20
  • Thu, Jul 25 2013 6:06 PM

    • redwire
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    Re: Two Layer Board with copper fill on top and bottom; Problems with Void touching Shape Reply
    It's very common for "film" layers to be used as a quick way to set up different visibility during routing.  These layers are not necessarily candidates for Gerber output.  This is what appears to be the case for your board...and I support that method as it has been the way Allegro was initially designed to be used.  So I think if you choose the correct layers in the Artwork output window you will get an error-free result.   Post back up if you have more questions.  Happy routing!!
    • Post Points: 20
  • Sun, Jul 28 2013 8:23 PM

    Re: Two Layer Board with copper fill on top and bottom; Problems with Void touching Shape Reply

    Hi Redwire,

    I have come across another problem. I added two internal plane layers to my *.brd design. One is labeled GROUND_1 the other is GROUND_2. I followed the directions to add Shape->Rectangular and selected the correct layer in the Options tab Etch/GROUND_1. Set the 'Shape Fill' to Dynamic copper. Then added the shape. I selected 'Assign a net name' to my GND net. After that was complete for both ground planes, I verified in the Visibility tab that the layers were there. The problem is no artwork is created for the ground planes. I go to Manufacture->Artwork and select the correct parameters. In the available films window, neither of the ground planes show up to be created. Is it possible I have a setting incorrectly enabled?

     Thanks, Richard

     

    • Post Points: 35
  • Mon, Jul 29 2013 3:39 AM

    • stump1019
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    Re: Two Layer Board with copper fill on top and bottom; Problems with Void touching Shape Reply

    You have to add the two ground layers to your fim files. Have you done that? For these film files you also need to determine whether you added your planes as a negative or a positive in the cross section, that also needs to be reflected in the film file.

    • Post Points: 5
  • Mon, Jul 29 2013 7:18 PM

    • redwire
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    Re: Two Layer Board with copper fill on top and bottom; Problems with Void touching Shape Reply

     Like stump says...you need to set up the artwork to generate the layers.   Take a few minutes to peruse the artwork output tab and right mouse on some of the existing layers and see what is there...try right clicking on a folder and add->new; you can exit out of artwork and set up the layer you want to generate artwork from and go back in to Manufacture->artwork and right click on the folder, "match display" and you're pretty much done.  You'll need to decide if you want to turn the planes positive or negative and choose a few more options and then generate.

    • Post Points: 20
  • Wed, Jul 31 2013 7:28 PM

    Re: Two Layer Board with copper fill on top and bottom; Problems with Void touching Shape Reply

    Thanks, Stump/Redwire.

     I think I have the gerbers complete. I have zipped them up and attached them. Would either of you have a moment to look over them and let me know what mistakes need to be corrected before I send these files out to be fabricated?

     Many thanks, Richard

     

    • Post Points: 5
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Started by NelsonsTrfgr at 17 Jul 2013 06:37 PM. Topic has 10 replies.