Swapping of layers on the PCB Board

Hello Rohit,

You can always use the Z-copy command. There are couple articles in the COS site that explain how to use it. Here's the link to them: 

Article (11009846) Title: How to copy a cline to another layer in Allegro
URL: https://support.cadence.com/apex/ArticleAttachmentPortal?id=a1Od0000000nboiEAA

Article (20204744) Title: How to copy a shape to several classes across the board.
URL: https://support.cadence.com/apex/ArticleAttachmentPortal?id=a1Od0000000tMieEAE

And here's the content of one of them (you can use the same procedure but applied to different elements):

1. Select Edit > Z-Copy.

2. Select only Clines in the Find filter.

3. In the Options window, change Copy to Class/Subclass to the new subclass to which you want to copy the cline.

4. Select the clines individually or using a rectangular selection.
5. With the clines highlighted, right-click and select Done from the pulldown menu.

You will see a copy of the cline/s on the destination subclass.

You can use the edit / change / cline to change the cline to another layer.

for swapping layers, i would use 2 files, file a with layer 3 (removed layer 4) and file b with layer 4 (removed layer 3).

with z-copy command, u can move objects on layer 3 to layer 4 on file a and objects on layer 4 to layer 3 on file b.

u can import layer 4 of file a into file b by sub-drawing.

u would need to adjust the padstacks.

Here's an easier method:

Move the clines on layer 3 to clear the board outline. for example, move clines ix 50.

Use Edit/Change/Cline to change the clines on layer 4 to layer 3.

Change the clines that were moved to be on layer 4. Move those clines back ix -50.

To keep any existing vias from connecting to planes when the clines were moved, you can use Edit/Property/Vias to assign property "Retain Net".