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[SOLVED] Via definition & routing on OrCAD - PCB Editor

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Member level 2
Member level 2
Jun 12, 2009
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there are some doubts I need to solve before adding vias to the layout.

  • Two types of vias are needed, through hole and BBvias, could the drill hole be the same for both of them?
    • Via Pad <= 0.3 mm
    • Via Drill Hole <= 0.15 mm
    • Which would be the recommended pad & drill hole for different kind of via?
  • Through Hole Via.
    • Is it needed to have available pad in every inner layer?
    • How can the pad be avoided into inner layers when it is only necessary to connect Top with Bottom layer? (Using "Suppress unconnected int. pads; legacy artwork" option from PAD Designer).
  • Through Hole & BB via.
    • At padstack definition, is it needed to define every layer on the future board (ex. 4 layers [Begin, L2, L3, Default Internal, End])? Or is it fine with simple definition (Begin, Default, End) and the later definition with BBvias setup and/or Constraint Manager?
  • B(lind)B(uried) via.
    • Which are the requirements for placing one via over another? (Stagger distance, number of layers at via definition).
    • Once, set the contraint manager parameters, is something else you have to do for adding several vias to join several layers?
  • Thermpad QFN ICs.
    • At a QFN IC, a thermpad is present, then vias have to be added. At Pad Designer, this thermpad includes the drill hole parameters, and a multiple drill with the number of vias and their respective clearance (X,Y). How can these vias be defined to fit board requirements.
    • I suppose this thermpad need to be added on constraint manager too. Is this right?

And finally, to sum up the steps to be able to add vias to design are:
  1. Create the via pad on Pad Designer.
  2. Make definition for similar vias from BB Vias Setup on PCB Editor. Setting start & end layers.
  3. Add via to physical contraint set, at respective top layer.
  4. At routing time, select start (Active) & End (Alternate) layers.
Is this right?

Kind regards!

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