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

NelsonsTrfgr

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

  • redwire

    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.

  • PRASH36
    Hi,

    Make sure that there is no OUT OF DATE shapes

    Display-->status
  • NelsonsTrfgr

    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

     

    ept_3000_tw_u2.zip
  • redwire

     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.

     

    ept_3000_tw_u1a.zip
  • NelsonsTrfgr

    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.

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