Start a new topic

DFM - Touching Net Objects


I have a PCB with short between via and plane. They assigned to different net as you can see in the attached picture. How can I find this short?

I performed a Complete PCB check with Compare Net File but can't see this error in the results.

Thank you


Thanks for your question.  Netlist Comparison will find that net error.  DFM Check is primarily used to check the manufacturability of the PCB.  Netlist Comparison ensures the electrical/net connectivity of the PCB.

Just curious where is the original data coming from?  

Gerber: If it were from Gerbers, there are no nets assigned.  FAB 3000 always runs "Netlist Extraction" (prior to DFM Check).  During netlist extraction, that circle would automatically be   included into the Net of objects it is touching.  When you run "Netlist Comparison" - check Gerbers against actual IPC Netlist file - it would highlight this net error. 

I personally haven't seen two different nets objects touching in an outputted ODB++/IPC-2581 file - should be obvious to any layout software before exporting fine.  However if you experience bad ODB++/IPC-2581 files, I would suggest "always" checking the box "Overwrite Nets" during DFM Check setup.  This lets FAB 3000 generate a new netlist (based from actual design objects) - and you can simultaneously run Netlist compare (check box:  Compare Net File).  

Note: Feel free to send me any sample ODB++/IPC-2581 files that had (different touching nets) and we'll be happy to highlight/pinpoint this issue during import - so the user is aware immediately of potential Net discrepancies - and uses FAB 3000 to regenerate a clean netlist.

Thanks again.

Best regards,


Simon Garrison - Applications Manager

Visit Numerical Innovations
Login or Signup to post a comment