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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.

 

 

 

Parents

  • 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

     

Reply

  • 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

     

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