[sdiy] ARM Cortex M4F chips with CODEC interfaces & DIY-friendly packages

[charlie wallace]

I don't think QFN's are that much harder, only the the bottom pad,
fill via vias , hot plate or hot air , but you can hand solder the
rest just as easily.

Personally i think they're easier to hand solder, my teach the newbs
project is a 20 pin QFN with a pad and 1206/0805/0603 LED's. They're
harder to bridge and you just do the tag one corner, opposite and drag
it just the same as pins.

Or you can line of paste along the pads and hot plate, or drag again.

We've had people of all ages and skillsets manage these QFN's with not
many  issue, certainly no more than with QFP's, in the classes,
bridges have caused more people to lift pads than anything else.

as for precision we did a dumb test which was, how sloppily could you
throw a QFN onto solder paste/pads (on a hotplate) and it still
worked, we got to the point where i could toss the chip onto the pads
like a carnival game and i'd still solder correctly. They were smaller
QFN's

we've hand built 100's of these at conferences and classes, some hot
plate, some hand solder only.

http://farm6.static.flickr.com/5170/5327863563_4e345db3c8.jpg
http://oldwiki.032.la/images/thumb/CyIII_proto.jpg/600px-CyIII_proto.jpg
http://aweplanet.com/braydon/files/2011/08/closeupcylonII-e1312226429340.jpg


cheers

On Tue, Sep 16, 2014 at 6:15 AM, Robin Whittle <rw at firstpr.com.au> wrote:
> I mentioned an ST chip in a UFQFPN48 package:
>
>   http://www.st.com/web/catalog/mmc/FM141/SC1169/SS1577/LN1877/PF260148
>
> because it had fewer pins than LQFP-64 packages - so I thought it might
> be more DIY-friendly.  However, after looking at the data sheet, page
> 122, I think this is not the case.
>
> As far as I know, 0.5mm LQFP packages could be soldered by hand, by
> filling the area with solder and removing what is not needed with wick
> or a desoldering tool.  I have never tried anything like this - can
> anyone report success or otherwise?
>
> However, the UFQFPN packages have no leads - just solder pads on the
> inside edge of the bottom of the package, so there would need to be
> solder paste put in place with a stencil, precise alignment, perfect
> heating etc, and no chance for inspection or solder sucking if things
> didn't work out well.
>
>   - Robin
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