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]joerg...@analogconsultants.com> 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 If a book has reached its 2nd anniversary it might already be outdated in wide stretches.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/ _______________________________________________ geda-user mailing list [9]geda-u...@moria.seul.org [10]http://www.seul.org/cgi-bin/mailman/listinfo/geda-user 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:joerg...@analogconsultants.com 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@moria.seul.org 10. http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
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