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Allegro PCB Designer : Interlayer Spacing ?

mxlecanu

Hi,

 I'm currently working with Cadence 16.5 and I would like to add an interlayer spacing constraint for two adjacent layers, in order to prevent interlayer crosstalk between differential pairs.

I spent some hours looking for a solution, and I found this post : http://www.cadence.com/forums/p/18113/1251634.aspx where Icanx2 talks about “PCB Interlayer Clearance Rule”.

I searched into Cadence's help and found a procedure to set interlayer spacing rule, but the problem is that the first step is : Choose Rules - PCB - Interlayer - By Layer Pair, but I couldn't find this menu anywhere in the GUI...

I also found a command line to set this parameter : "rule PCB (inter_layer_clearance 1.2 (layer_pair cc via))", but when I use the same command line with the layer names corresponding to my layout, Allegro tells me that the command couldn't be found...

If someone already worked on interlayer nets spacing and knows how to set a rule generating a DRC this would be really helpful.

 

Thank you very much,

Have a nice day. 

  • pcbnagaraj
    They are the rules used in Allegro Auto router . I have not used it , but you can refer to the Allegro PCB Router Command Reference document in the Allegro help for the procedures and usage.

    Thanks,

    Nagaraj.
  • mxlecanu

    Hi Nagaraj,

     Thanks for your help.

    Does that mean that it is only available with auto router ? Do you know a way to set a similar constraint for manual routing process, which would generate a DRC ?

    I already looked at Allegro Router Command Reference Manual, and the first step of the procedure is to go to Rules -> PCB -> Interlayer -> By Layer Pair. But I couldn't find it in the Allegro PCB Designer GUI... (which could be explained if only available for autorouting...)

     Thanks again,

    Maxime

  • lcanx2
    You may want to try setting your layer to layer spacings in the PCB Router GUI itself.

    From the Allegro pulldown menus:

    Route->PCB Router->Route Editor…

    Then, from the Pulldown menus of the Router GUI, access the Interlayer clearance settings by choosing:

    Rules->Class to Class->Interlayer

    After entering your spacings and choosing your assignments you should end up with a rule looking similar to:

    rule class_class _difpr_QLM0_RX_0 _difpr_QLM0_TX_1 (inter_layer_clearance 10 (layer_depth 5))

     
    Bill
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