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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

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  • 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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  • 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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