[sdiy] Starting with SMT hand-soldering

[Dave Manley]

 On Thu 10/10/28  1:58 PM , "Jason Tribbeck" jason at tribbeck.com sent:
> On 28 October 2010 21:47, Dave Manley  wrote:
> 
>  On Thu 10/10/28 12:17 PM , "David G. Dixon" dixon at interchange.ubc.ca
> sent:
> > > I'd like to try my hand at laying out and
> > hand-soldering an SMT board and> thought I'd stop in here to see what
> advice I
> > could get from those that> have done it.
> >
> > Go see Rick Moranis about getting yourself shrunk...?  :o)
> 
> Short of doing that:
> 
> For chip resistors/caps: holding the part with the tweezers, solder down
> one end.  Move on to the next component, only soldering down one end of
> all the caps and resistors, then make a final pass soldering the other end,
> and touching up as necessary.  Some people will object to this, but I find
> this is the fastest.
> 
> For leaded ICs: solder down one corner, then solder down the opposite
> (diagonal) corner.  If all the leads aren't perfectly lined up on the
> pads, adjust the corners until you get it right.  Then solder all the
> other leads, using lots of solder flux, dragging the wetted iron while
> applying more solder, solder all the leads on one side in a single pass.
>  With practice you can get very good at this and not need to do much touch
> up, or cleanup with solder wick.  There's no reason to solder one lead at
> a time!  Don't do it!  :-)
> 
> This reminded me of something: I use a pair of tweezers which are normally
> closed for the resistors/capacitors, which means you don't get too tired
> doing a lot of them. But I also only solder one side at a time (I also try
> to tin the pads in the same orientation so I don't need to spin the PCB
> around too many times).
> 
> The technique for chips described above does work very well, but it did
> take me a while before I was comfortable doing it - for a while, I found it
> easy to do 1.27, but difficult for 0.8, and then easy for 0.65 and smaller.
> I think it's because the 0.8mm is close to my soldering iron tip size, and
> I couldn't drag the solder properly. However, after a bit of practice, I
> think I've got it cracked.

The other thing I like to do when putting down chip resistors/caps, is to put a little bit of solder on one of the pads first.  Then you only need two hands to put the part on - step one put the solder on, step two with the tweezers slide the part into the pre-soldered pad that you're heating with the soldering iron.  If you pre-load one side of all the component pads with some solder, then assembly goes much faster.

-Dave