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Constraints for fanout

Hossein1357

Hi, 

I want to create some rules for Allegro PCB when it creates fanout for my BGA. I have defined two types of VIAs and I want to force Allegro to use one VIA - and thick track width -  for Power& GND pads and other VIA - with thinner track width - for signals. Where can I define such rules?

Any suggestions are welcome.

Hossein 

  • chads108

     You will need to create a shape on a constraint region layer encompassing your BGA  .  In Constraint Manager you will then create physical and spacing constraints for that region specifing the different vias, line widths and spacings. The physical constraint you create is then assigned to the constraint region you created on the board.  Fanout should then follow the contraints for that region. 

    I actually build the constraint region into my BGA footprints since more often than not, the etch widths and spacings are going to be different in these areas and that way I only need to assign a constraint to the already defind region.

    Chad

  • Hossein1357

     Hi,

    I have created constraint region for Power & Signal pads below BGA and have assigned some Physical constraints in CM to these two regions. I tried Route->PCB Router->"Fanout by pick" and it worked. However, as shown in below picture it does not obey the orientation - BGA Quadrant Style - for some nets. I should add that I have not yet created any spacing constraint!. If I use "Create Fanout", router will follow that Style without using predefiend vias in constraint!.. I don't see which method I should use?!.Or, how can I correct this?

    https://drive.google.com/file/d/0BzS3_lT7y4tEWk9aSHhlNDVKTlE/edit?usp=sharing

     Any comments are welcome.

    Hossein

  • Hossein1357
    Long time sience I wrote this post and still didn't get any answer. Can anybody help please?
  • Hossein1357

    Long time sience I wrote this post and still didn't get any answer. Can anybody help please?

  • steve

     Route - Create Fanout is easier to control. You can either fanout by symbol or by pin (or window) so set your rules up and then look at the Options menu to define direction angle etc then window the pins. BGA quadrant type works well for the four quadrants of the BGA.

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