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Re: A few extra component footprins


On Thu, 26 Aug 2010, Alex G wrote:

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There are named "land patterns" on maxim's website:

Yes, there are both land patterns and package outlines,
but there's an awful lot of them to go through ...

I know what you mean. I have a hard time navigating that maze. Still,
for TDFN, there aren't that many. I'd be glad to harvest some information.

There's one thing that puzzles me - the Maxim datasheet lists two
versions of the package for N=8 and three each for N=10 and 14,
but unless I'm blind, all variants have identical dimensions ?

There are a few duplicates, but there are some 3x3mm TDFN packages and
some 2x2mm packages.

I've looked at some of the datasheets above, and I think the datasheet
http://pdfserv.maxim-ic.com/package_dwgs/21-0137.PDF is wrong
- the difference between the variants seems to be the size of
the exposed pad (D2,E2), but 21-0137.PDF lists them as identical.

I'm not sure what you mean.
http://pdfserv.maxim-ic.com/package_dwgs/21-0137.PDF lists the size of
the exposed pad as identical for variations of the same N. For N=14 D2
is 1.7mm instead of 1.5mm.

Well, that's what I meant - 21-0137.PDF lists _all_ dimensions for
the "same N variations" as identical, which doesn't make sense.
The other datasheets on maxim-ic.com
lists varying sizes for the thermal pad.

I think there are also larger packages as well;

Yes, much larger - up to 56 "pins" :-)

AFAIK, TDFN only goes to 14 pins. TQFN on the other hand, does go to 56.
I think you're referring to TQFN. I'll look over the .dim and see if I
can get some dimensions in (If I can't then I should probably try to fly
to save the world from an idiot mind :p ).

You're right - I overlooked the TDFN vs.
TQFN when searching for the max size :-(

What do you want to do about the molex connectors? If I had the
generator script, I could play around with it and see if I can get some
work done on the connectors. It could also be of great help if we could
convert IGES to VRML automatically. Worst case, I'd have to manually do
it for 100+ connectors

I've taken a quick look at the IGES file format, and
it's fortunately not binary, but (sort of) human readable
ASCII (in good ol' punched-card 80-colums fixed format :-)

There's a Wiki page on IGES: http://en.wikipedia.org/wiki/IGES,
but it doesn't go into enough detail to be _really_
useful (some of the info is there, but not all).

There are a few PDF files listed under "References" on the wikipedia
page, which seem to deal with the standard. But at multi-hundred pages
long, they shouldn't be read by anyone. I'll keep an eye out for a
*readable* spec.

Ref 5 looks interesting, but www.uspro.com times out :-(

I haven't understood what all the numbers and fields means yet, but
as freecad can read IGES (*), the freecad source should also contain
some useful info for writing a script to convert IGES to VRML.

(*): Well, sort of - freecad is definitely alpha code:
I've tried feeding the simple example on the Wiki to freecad,
and it gets the coloring wrong - the points, arcs and lines
should be yellow, red and green, but they're all shown in black.
Also, Wiki Ref 6: http://www.wiz-worx.com/iges5x/wysiwyg/f214x.shtml
is totally wrong (most of it is missing).
Fortunately, the missing stuff is 2D graphics, and the Molex
connectors shows up just fine (except for the coloring).

Hmm, I just noticed that IGES contains color information. If it's any
consolation, not even Inventor can get the color right (well, except for
the yellow lines).

I found an open source (Java) IGES viewer on
but unfortunately, it's 2D only.

It does get the colors right, though, so I'll
take a look at the source when I get the time.

IGES contains a lot of advanced features, such as
spline curves and surfaces, so how easy it is to translate
an IGES file to VRML depends on which features are used.

As KiCad only understands VRML IndexedFaceSet and materials,
any 1D and 2D info (points, lines, arcs, etc.) in an IGES
file will get lost - only the 3D faces can be converted.
However, that should be enough for kicad, I think.

Yes, the 3D faces are all that's needed in kicad. I'm not sure how the
pieces are supposed to be colored; Inventor displays the body and pins
as one piece, in one color.

Worst case scenario, there's also the possibility of converting PRO/E or
STEP files, as molex provides all three variations (though I think STEP
is binary).

... or create the 3D view ourselves from perl :-)

I don't know which will be easiest, as that depends on the
available info on the file formats - probably not much :-(


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