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BGA and High Speed Board

autodeskguest

Hi

 

I would like to have some feedback of your experiences with the design

of complex boards that use BGA and have an High speed Address/Data Bus.

 

For example a system of :

          100Mhz Bus Speed

          32 bit Data Width

          14 bit Address Width

          Processor (BGA) +

          2 SDRAM(TSOP54) +

          FLASH(TSOP48)

 

Of corse I speak about handly routing with Eagle.

 

Does some one do that before?

 

Does any one have some special techniques and/or tools to easly do this job?

 

What about the placement strategy of the placement?

 

What is the traces width for a 0.8 mm pitch BGA?

 

What about respecting the traces lenght matching of the bus signal?

How to deal with accordion traces?

 

Do you think it's crazy to make a complicated ulp that help for

interactive routing?

 

There's a lot of questions but I will not charge you a lot.

 

Thank's in advance

 

BR

 

Abdallah MEZITI

 

 

 

 

 

 

 

  • abdAllah Meziti wrote:

    Hi

     

    I would like to have some feedback of your experiences with the design

    of complex boards

     

    I have no experience of such multipin components, but...

     

    What about the placement strategy of the placement?

     

    Move them around in Eagle until it looks good.

    (see the airwires)

    Of course you need understanding of length matching data/clocking lines

     

    Eagle autorouter is speedy and i often test the placement by running it

    shortly, ripping up, move components, retry.  For finishing, I often end

    up roputing it all manually however, but see below.

     

     

    What is the traces width for a 0.8 mm pitch BGA?

     

    Ask your manufacturer how thin traces and isolation distances he can use

    at what cost levels, if he can do micro vias, sizes of vias etc...

     

    What about respecting the traces lenght matching of the bus signal?

    How to deal with accordion traces?

     

    (not my cup of tea)

     

    Do you think it's crazy to make a complicated ulp that help for

    interactive routing?

     

    Absolutely, use what exist;

    You can export to the java program http://freerouting.net/ and back to

    eagle.

     

    That said of course set up GND plane, maybe power plane and route power

    and decoupling manually, maybe clocking, oscillators and such.

    Then save that, before autorouting.