Re: gEDA-user: good books about footprint and land patterns

[Vara Prasad Goluguri <varaprasad.goluguri@xxxxxxxxx>]

   Creating footprints probably depends on what software you use.
   I have been doing it with gEDA and it hasn't been too hard.
   Get the specs for the IC and understand. Feed in values into one
   of these programs (understand them as well) and get the footprints you
   want.
   I use programs and do some manual editing.
   [1]http://www.brorson.com/gEDA/land_patterns_20070818.pdf
   [2]http://www.dlharmon.com/geda/footgen.html
   [3]http://luciani.org/geda/pcb/pcb-perl-library.html#tqfn
   I agree with Joerg, books are not the only answer. Lots of things are
   said in the books
   and one would end up have a feeling that not a single PCB was ever
   done.
   Play first and then books.
   / Vara

   On Fri, May 15, 2009 at 8:21 PM, Joerg
   <[4]joergsch@xxxxxxxxxxxxxxxxxxxxx> wrote:

   Jelle de Jong wrote:
   > Hello everybody,
   >
   > What are good books that explain how to create good save footprints
   from
   > datasheet specs. I am searching for best practices, math rules and
   so forts.
   >
   > I need to create save footprints for BGA's and other very small
   > components that probably go into reflow soldering. I would like to
   know
   > how to make footprints if only the dimensions of the part is know
   and no
   > recommended pad layout is provided there is also an difference
   between
   > layout when reflow and wave soldering. I would like to see more
   science
   > and less trial and error, because it takes to much time and money.
   >
   > [5]http://tinyurl.com/pp8xnv
   > [6]http://tinyurl.com/octvzu
   >

     Honest opinion: I do not believe books are the answer here.
     Technology
     progresses fast, both in therms of packages and assembly process.
     If a
     book has reached its 2nd anniversary it might already be outdated
     in
     wide stretches. My sources boil down to manufacturer's guidelines
     and if
     in doubt a quick chat with the guys at the assembly plant or my
     layouter. Since I contract out the layouts and use a very
     experienced
     (a.k.a. older) layouter he is always in contact with the major
     assemblers and knows the land patterns du jour in his sleep.
     Because
     that's what he does all day long.
     Large semiconductor manufacturers also offer a wealth of
     information. I
     have most in hard copy (a whole binder) but much is available
     online.
     Just one example:
     [7]http://www.standardics.nxp.com/support/documents/logic/pdf/dqfn.
     solder.pdf
     --
     Regards, Joerg
     [8]http://www.analogconsultants.com/

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References

   1. http://www.brorson.com/gEDA/land_patterns_20070818.pdf
   2. http://www.dlharmon.com/geda/footgen.html
   3. http://luciani.org/geda/pcb/pcb-perl-library.html#tqfn
   4. mailto:joergsch@xxxxxxxxxxxxxxxxxxxxx
   5. http://tinyurl.com/pp8xnv
   6. http://tinyurl.com/octvzu
   7. http://www.standardics.nxp.com/support/documents/logic/pdf/dqfn.solder.pdf
   8. http://www.analogconsultants.com/
   9. mailto:geda-user@xxxxxxxxxxxxxx
  10. http://www.seul.org/cgi-bin/mailman/listinfo/geda-user


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