Converting Existing Rigid-Only Design to Rigid-Flex In Allegro...

Hi,

I have a current fairly complex 8-layer rigid-only PCB .BRD design that was created for a client about a year ago. They are now needing me to take the existing design, add (x4) flex cables extending out from it and then add (x2) small 2 layer rigid-only PCBs to the design.

In the 'Allegro / OrCAD 17.2 Rigid Flex Design Creation Best Practices.PDF' supplied by Cadence, on page #24, it is mentioned that when creating new PCB stackup zones for rigid-flex:

"When a zone is first defined with pre-existing symbols, traces, vias, or conductor shapes within the boundary, the stackup assignment for that zone may fail. The symbols, traces, vias, conductor shapes must be moved out of the area where the zone will be defined, and the stackup reassigned. After that the moved or deleted objects can be replaced. Traces and shape placement within a zone will fail if the layer they are defined on no longer exists."

So in another words, before adding PCB stackup zones to an existing PCB design, all objects (copper, vias, parts, etc.) need to be moved (or exported to subdrawing(s) ) out side the Board Geometry OUTLINE (now in vs 17.2 it is DESIGN_OUTLINE) subclass.

This existing design has many different power net dynamic shapes on 2 inner plane layers. When I attempt to save these layers in a subdrawing file and import them back in, the priority of many of the shapes get changed, therefore messing up many of the power planes. Also because of this, due to the dynamic net assignment of copper / vias when importing these shapes back in, some parts that on the top and bottom layers have their pins / copper shapes reassigned to incorrect nets.

In the past, I have been using a separate Skill file 'assign_net' to re-assign pins / vias / copper to the correct nets. It works but it is a bit cumbersome to use, especially if there are a large number of nets to be re-assigned.

Questions:

1) Is there a suggested way of taking an existing rigid-only PCB design over to rigid-flex without this much complexity (to be able to create new PCB stackup zones)?

2) In 17.2, is there a way to re-assign nets to copper?

Thanks,

Danny