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Help defining layers for DRC

KennyMillar

I would like to start work on a 4-Layer board, with layer 2 being a VCC supply layer, and 15 Being a GND supply layer.

 

On DRC I have define the layers as : ((1*2)+(15*16))

And I have named layer 2 as $VCC and 15 as $GND

 

When I try to autoroute the board I get : "Cant route blind/buried vias together with supply layers"

 

I think the problem is I don't fully understand the syntax for defining layers in the DRC dialog.

 

All help and suggestions at this point are welcome!

  • Hi,

     

    The main error here is you are using buried vias on the supply layers - GND and VCC. Pads and vias do not work with supply layers. You could probably either use only a blind via from Layer 1 to Layer 16 or if you really want to use the buried vias, then you will have to skip the supply layers.

     

    Here are some important points to keep in mind when having supply layers in your design:

     

    Specials of a Supply layer
    a) The layer is displayed inverted, i. e. everything drawn in this layer is non-copper on the real board.
    b) This layer does not work with Pads and Vias. Connected elements will automatically get Thermal symbols if required, isolated elements will get isolating rings, so-called Annulus symbols. The dimensions of these symbols can be adjusted in the Design Rules' Supply tab.
    c) To keep the board edges free of copper draw an isolating WIRE near the border. This avoids possible short circuits between adjacent (Supply) layers.
    d) It is not possible to draw traces in a Supply layer (inverted display!).
    e) For manufacturing data generation (for example Gerber) with the CAM Processor you have to activate the Supply layer only, nothing else! No Vias, no Pads!
    f) And again: The layers Pads and Vias have nothing to do with the Supply layer. To see what's the matter in this layer you have to display only this Supply layer. And remember the inverted display.

     

    Hope this helps.

     

    Best Regards,

    JayaB

  • in reply to Former Member

    Thanks - that makes sense.

    I changed my layer definition to (1*2+15*16) and that seems to work for me.

  • in reply to KennyMillar

    On 6/30/2010 5:05 AM, Kenny Millar wrote:

    Thanks - that makes sense.

    I changed my layer definition to (12+1516) and that seems to work for me.

    >

    I would recommend that you use EAGLE's other mechanism for producing

    copper planes - polygons. I think polygons are much easier to use, the

    tutorial has a good explanation of how to use them. they will also allow

    you to place tracks in the copper plane if you need them.

     

  • in reply to Former Member

    I'm not sure about using polygons as supply layers.

    I'm very au fait with using polygons, and would rather use Eagle's built in supply layer features.

  • in reply to KennyMillar

    Kenny Millar wrote:

    I'm not sure about using polygons as supply layers.

    I'm very au fait with using polygons, and would rather use Eagle's built in supply layer features.

     

     

    Almost certainly at some point you are going to need to use polygons.

    Examples are flooding unused area on the top/bottom with copper,  making

    large copper areas to heatsink a part.   The limits of Supply layers are

    well discussed both here and in the tutorials/manual.   It is not

    difficult to draw a polygon on a layer and then name it (GND, VCC or

    whatever).

     

    Jim

     

     

  • in reply to Former Member

    Thanks for the reply, but like I said - I am au fait with polygons. I use them all the time.

    I flood fill top and bottoms layers all the time. I don't need help with polygons!!!

     

    Eagle has support for supply layers and I'm using that feature.

    My original problem was resolved by defining the layers correctly in DRC.