ivp wrote:
> Have to say I'm wondering about hand-working these MCP1640
> DFN-8 packages though. MSOP8 is bad enough

I've had to do a few small packages lately.  After some experimentation I
found a way that seems to work OK for doing these by hand.  First you put
extra solder on the pads on the bare board.  Make sure there aren't solder
bridges.  This can usually be done just by dragging the soldering iron over
each pad.  If that doesn't work you used too much solder, so clean some off
with a solder wick and try again.

Once you've got solder on all the pads, smear the whole area with paste
flux.  Make sure this is non-conductive, like rosin, since it's not going to
get cleaned off under the package.  Now place the package in the correct
position on the pads.  The paste will stick it loosely to the board.  Align
it correct.  A magnifying light and tweasers help a lot.

Now you've got the package sitting on its pads held there by a layer of flux
paste.  Flow the solder with hot air at 650 degF or so long enough for the
flux to smoke for a few seconds.  Sometimes you can see the solder melt, but
usually not.  If the flux stops smoking you're definitely done, although you
don't need to hold the hot air on it that long.

I've done some QFNs that way, and a few TQPF 64 pin PICs.  For me the
hardest part is lining up the chip correctly before applying heat.  A
magnifier helps, but the hand movements need to be really tiny.  Once it's
properly lined up, the actual soldering is fairly easy.


********************************************************************
Embed Inc, Littleton Massachusetts, http://www.embedinc.com/products
(978) 742-9014.  Gold level PIC consultants since 2000.
-- 
http://www.piclist.com PIC/SX FAQ & list archive
View/change your membership options at
http://mailman.mit.edu/mailman/listinfo/piclist