[sdiy] SMD soldering video

[Dave Manley]

> I'd tend to agree - it seems pretty wasteful.
>
> I've been able to solder 0.5mm pitch parts (up to QFP80 so far) 
> without too much trouble. The trick I use is pre-tinned PCB pads and a 
> dab of liquid flux. Position the part, tack two opposing corners, 
> apply a drop of flux and then merely heat the pads. The pre-tinned 
> solder on the pad will melt and the flux cleans the surface, allowing 
> it to flow to the part leads. This give an extremely clean joint with 
> no excess or bridging. The main difficulty is cleaning the excess flux 
> off afterwards, but an old toothbrush and some isopropyl seems to do 
> the trick.
>
> The main advantage of the Spark-Fun technique seems to be that they 
> can do it very quickly without giving each lead individual attention.
>
> Eric
The method I'm describing is very quick.  After the corners are tacked 
as you describe, it takes about 10-15 seconds per side of a  large 
PQFP.  If you're lucky you get no bridging.  If there is bridging, 
typically drawing a clean (dry) iron across the joints will usually 
clear them.  Last resort is to bring out the solder wick.  For cleaning 
we used IPA with a brush with short, stiff bristles. (It's nice to have 
de-ionized water and an air compressor too ;-) )

Once you've tried it a few times and figure it out, you'll wonder why 
people complain about SMT.

BTW, I learned this technique from an incredibly skilled technician, who 
used it day after day assembling engineering prototypes.

-Dave