kicad-developers team mailing list archive

[Lorenzo Marcantonio <l.marcantonio@xxxxxxxxxxxx>]

On Tue, Apr 22, 2014 at 11:31:03AM -0400, Carl Poirier wrote:
> So in this case, let's keep what was said before; origin in the middle of
> SMT, origin on pin one of THT, which is put in the first quadrant.

There actually is a standard for both pin 1 and orientation. Well, *two*
standards :D both IPC (IPC-7351) and IEC (61188-7) have it... the
important thing is that the middle is determined by leads, not body.
Also, at least here in Italy, many people always use the centroid (even
for THT). Finally, there is the EIA-481 (the reel/tube standard) and,
anyway, each manufacturer does *whatever he want*.

In fact most placement systems use three alignment point: the CAD
insertion point, the nozzle/pickup point and the pin 1 point. Pick and
place software and the operator make everything match (more or
less...). That is unless the operator declare the reel orientation in
the wrong way (happened to me:D)

My suggestion is: pick a standard and follow it. Most other CADs seems
to follow the IPC rules, anyway.

For other info search around for 'PCB Design Optimization Starts in the
CAD Library', it explains many things quite nicely.

> Are there any opinions about schematics using millimeters, which I
> mentioned earlier?

IIRC the metric schematic proposal was rejected. Don't remember the
exact reason. There is a technical issue, however: internally eeschema
works in decimils and rounding kills endpoint testing.

-- 
Lorenzo Marcantonio
Logos Srl