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When testing FAB 3000, I have purposely added many shorts and opens to our design.

When testing FAB 3000, I have purposely added many shorts and opens to our design. When running the Netlist Comparison, FAB 3000 is telling me that I have a short in locations where there should not be any and not finding shorts where they are located. I am confused why each error is not pinpointed?

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Thanks for your response.  Please see below for my responses.

Netlist Compare:

  • If the board passes FAB 3000 netlist comparison, than the electrical integrity of the PCB is good.  This is the primary goal to ensure electrical integrity.
  • If the board has only one open/short, FAB 3000 will pinpoint that specific location and CAM net. 
  • If the board has multiple shorts/opens, it's difficult to pinpoint all locations due to other "unintended discrepancies" that may occur because of the multiple shorts/opens could completely affect the entire electrical integrity.  

Note:  Typically when any Opens/Shorts are detected, you would need to perform a Step-by-Step deduction process (see below).  For example in your sample design, FAB 3000 pinpointed the first open VDUT4/VMON4 at (11.005, 6.434).  The design engineer would need to perform the following:

  1. Review this open first (back in their CAD tool). 
  2. Make any necessary corrections. 
  3. Re-run the Netlist compare check with FAB 3000 on the new gerbers.  

If FAB 3000 netlist compare passes, than the updated design is now good (all other warnings were simply a compounded byproduct from the open/short).   If FAB 3000 finds other opens/shorts, than use the new location and net for that error and repeat steps 1-3 above.   Trying to fix multiple opens and shorts simultaneously is recipe for disaster.  Methodically fixing opens/shorts one at a time is the most reliable method.

I understand your concern because of multiple errors/warnings that do not all seem correct.  However if the board is good, FAB 3000 will pass it.  If the board is bad, FAB 3000 correctly fails the PCB and issues warnings.  Fixing one error at a time (Back in CAD), and then re-running FAB 3000 netlist check until no errors are shown, will ensure the successful electrical integrity of any PCB.

Thanks again.

Best regards,

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