Re: gEDA-user: GEN_QFP and SOICs

[Dan McMahill <dan@mcmahill.net>]

On Wed, Apr 07, 2004 at 11:37:34PM -0700, hjohnson@sfu.ca wrote:
> Hello Folks,
> 
> I'm attempting to design a PCB using several SOICs (PIC, optical sensor,
> and the like). I've created the symbols for gschem, and given them the
> footprint attributes with GEN_QFP and the appropriate parameters, as
> described by qfp_ui.  The problem, here, is that when I attempt to use
> gsch2pcb, I just get horrendous errors on these items.  Does anyone have
> any thoughts?
> 
> One of the footprint attributes I'm using (defined in the tragesym step)
> is: 
> 
> GEN_QFP 8000 50 17 1 0 18 436 610
> 
> I am using the version of gEDA that ships with debian/unstable.
> 
> If someone could point me to appropriate documentation on how to
> generate the SOIC packages, (for PCB) or point out what I'm doing wrong,
> I would appreciate it.
> 

I'd recommend looking in the ~geda library that ships with PCB.  It
includes various SOIC packages as well as quite a large number of QFP 
packages.  I've not really used the qfp_ui ones.

Standard warning:  Please do some sanity checks on the footprints you use.
They may not be right.  This warning applies to essentially any footprint
library you ever get for any tool from anywhere!  Especially with things
like QFP and other fine pitch SMT packages, you find that there can often
times be differences that you don't notice at first glance until you go to
solder a part down and find out that your qfp package had a 0.5 mm pitch
and the footprint was 0.4mm or 0.65mm.  

-Dan

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