[sdiy] matrix ICs

[Theo]

May I suggest the "blob" method for soldering the TQFP?
I got this from a friend who works at a SMD assembly line, where 1 minute
for a 100 pin TQFP is already too slow. There is a web-page around about
this soldering method, but I don't have the URL, sorry.

- Flux your PCB (spray works fine), this is rather essential.
- Place the TQFP on the board.
- Next take a normal soldering iron with a +/- 2mm bit, larger is also OK.
- Now put a nice "blob" of solder on the tip of the iron and drag this over
the pins of the IC.
Done.

It takes some practice and you might want to keep a 0.8mm iron handy to
remove a occasional solder bridge.
(just reheat the offending pins)
But the emphases in on occasional, most of the time it works like a charm.

There is one thing though you need to take in account.
While designing your PCB you should make sure there is a copper-area (large
trace, ground plane, ect.) next to the pads of the IC your gona "blob".
Your "blobbing" ends on this copper-area so the excess of solder has a place
to go.

I "blob" all my SMD ICs and am quite happy with it :)

Theo


From: Alex Stettler <alex at xatomic.ch>



> Hi all,
>
> I'm currently designing a 32-channel patch-cordless patchbay (PCLPB) with
> four AD8113 chips.
> These are 16x16 crosspoints and are specially designed for audio purposes.
> They have -100dB channel crosstalk, 100dB isolation at 20kHz and a +/-12V
> supply.
> The outputs are buffered.
> They come in a 100pin TQFP package.
> So I'm very curious on the results of the finished product and I hope I
> could manage
> to solder the chips properly to the PCB as such a 100pin TQFP is a rather
> small chip.
> But it should be possible with a hot air gun and solder paste.
>
> Regards,
> Alex
>
> > -----Ursprüngliche Nachricht-----
> > Von: owner-synth-diy at dropmix.xs4all.nl
> > [mailto:owner-synth-diy at dropmix.xs4all.nl]Im Auftrag von Glen
> > Gesendet am: Samstag, 6. Oktober 2001 08:57
> > An: synth-diy at dropmix.xs4all.nl
> > Betreff: Re: [sdiy] matrix ICs
> >
> > Just to pass some time, I compiled a list of known cross-point
> > switches where
> > are still considered to be in active production. You can find
> > that list here:
> >
> http://users.ezwv.com/~mclilith/electronics/cross-point.html
>
> Perhaps it will be of interest to someone.
>
>
> Later,
> Glen
>