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

[Joerg <joergsch@xxxxxxxxxxxxxxxxxxxxx>]

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.
> 
> http://tinyurl.com/pp8xnv
> 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book has reached its 2nd anniversary it might already be outdated in 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:

http://www.standardics.nxp.com/support/documents/logic/pdf/dqfn.solder.pdf

-- 
Regards, Joerg

http://www.analogconsultants.com/



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