kicad-developers team mailing list archive

["�vind Aabling" <Oyvind.Aabling@xxxxxxxx>]

On Thu, 26 Aug 2010, Alex G wrote:

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> > > Is it just me or are DFN8-M065 <-> TDFN8-M065 and DFN10-M05 <->
> > > TDFN10-M05 packages identical except that TDFN's have slightly larger
> > > pads?
> >
> > Very likely - my DFN/QFN lib is based on datasheets
> > from topline.to (they make dummy components).
> >
> > I've seen several variations in identical packages, when
> > comparing datasheets from different manufacturers, so
> > appropriate values must in some cases be guesstimated :-(
> For 3D packages, it's not that critical. For footprints, I would go with
> the more conservative values, such as the larger pads.
>
> I like maxim's documentation because it's complete, and quite
> conservative, and the components they make seem to always conform to
> specs, unline some other manufacturers.
>
> > In some cases, I've even resorted to measuring on actual
> > components that I happen to have laying around ...
> Ouch! You need a pretty good caliper to measure something that small.

I do have a digital caliper, but no, I haven't measured SMD
components, only stuff like transistors, DIPs and DB/DSUB :-)

Well, I did use a ruler to doublecheck the pin row-to-row
spacing (package outer dimension) on a few QFPs.

> > Also, some datasheets specifies min+max, and others only
> > the nominal size - I've chosen nominal (almost ?) everywhere.
> Nominal is fine, IMO. Nominal is a manufacturer's way of saying "it's
> how it should look, but we can't get it that exact".

Yep.

> Alex
>
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Øyvind.

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