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First Multilayer Board - vias question

autodeskguest

Hi,

 

I'm working on the first 4-layer board and I was unable to find the answer

in documentation.

 

I have 4 signal layers.

 

All my vias are simple ( no blind or burried vias to keep cost down).

 

Question : Are vias connecting in all 4 layers 1,2,15,16 always ?

 

Is it posssible to have let say via connecting 2 to 16 while there is a

polygon or very wide trace of another signal over the via  in layer 15 ?

 

If yes, how do I make it working?

 

Thank you.

 

 

 

  • Sagi Barak wrote:

    Hi,

     

    I'm working on the first 4-layer board and I was unable to find the answer

    in documentation.

     

    I have 4 signal layers.

     

    All my vias are simple ( no blind or burried vias to keep cost down).

     

    Question : Are vias connecting in all 4 layers 1,2,15,16 always ?

     

    Is it posssible to have let say via connecting 2 to 16 while there is a

    polygon or very wide trace of another signal over the via  in layer 15 ?

     

    If yes, how do I make it working?

     

    Thank you.

     

     

    For a 4-layer board, a hole is drilled through all 4 layers.  The via

    only connects the layers that you want.  In your example, that is layers

    2 and 16.  If the hole for the via is not drilled through all 4 layers

    then that is either a blind or buried via.

     

        -

      | |  -

      layer  1 (NOT connected to via)

              | |------  layer  2 (IS  connected to via)

              | |        layer 15 (NOT connected to via)

              | |------  layer 16 (IS  connected to via)

               ^-- via

     

    BTW, with 4 layer boards, usually the 2 inner layers are for power and

    ground.  If you really have 4 signal layers, then be sure to use fat

    power traces, and copper flooding (pour) for ground.

     

    HTH

    -Dave Pollum

     

  • Sagi Barak wrote:

    Hi,

     

    I'm working on the first 4-layer board and I was unable to find the answer

    in documentation.

     

    I have 4 signal layers.

     

    All my vias are simple ( no blind or burried vias to keep cost down).

     

    Question : Are vias connecting in all 4 layers 1,2,15,16 always ?

     

    Is it posssible to have let say via connecting 2 to 16 while there is a

    polygon or very wide trace of another signal over the via  in layer 15 ?

     

    If yes, how do I make it working?

     

    Thank you.

     

     

     

    The key is to make sure that your DRC is set up properly.

     

    In the DRC layers tab the Setup should be (12+1516) .

     

    If this is the  case then all vias will be straight through all layers.

    Read the accompanying explanation in the DRC layers tab for setting up blind

    and buried vias for future reference and to reassure yourself that the above

    setup is correct.

     

    cheers

     

    David