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Re: A few extra component footprins

 

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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