kicad-developers team mailing list archive

[Lorenzo Marcantonio <l.marcantonio@xxxxxxxxxxxx>]

On Wed, Aug 21, 2013 at 02:57:22PM +0200, Nils Hesse wrote:

> I'm happy that this really could be usefull to someone. I would like to
> create more footprint wizards and/or other plugins/scripts for KiCAD in the
> future.
> The code isn't really that much by the way, most of the code is
> "housekeeping" (clean console outputs) and the creation of silkscreen lines
> for the outline of the module (7 single lines).

Building it by hand is not too long, using a custom grid (and rotating
it for the other sides). However I would *not* like do hand draw
a socket 1366 :D (routing *that* would be a little hard in
pcbnew, anyway...) AFAIK the biggest QFP is 144 pin so I'm safe for now.

If you want documentation (i.e. the IPC formulas) for calculating pad
size and spacing from the package geometry I have written a tutorial
text on it (if you ever used LP Calculator or PCB Footprint Expert these
are the algorithm they use).

You can get it here:
http://www.logossrl.com/~mrclnz/ipc7351b-impl/ipc7351b-impl.pdf

It's freshly updated with the B revision (mostly they added the aluminum
capacitor and deprecated the SMD-mounted DIPs); we're waiting the C one
in a few months, however... do not worry, there is still people using
the old IPC-SM-782 footprints and the boards are working anyway!

You will need to download one of the two (free) calculators to have the
'magic numbers' to make the formula work (sorry, it's a paid standard
and I can't reproduce their tables). The new calculators are already
using the revision C tables, but they haven't actually changed a lot
(the big change is rounding and the silk/fabrication layout).


-- 
Lorenzo Marcantonio
Logos Srl