Re: gEDA-user: best ways to do SMT assembly

[Dave N6NZ <n6nz@xxxxxxxx>]

Robert Butts wrote:
> I'm sorry to start a new thread on this, I can't find saved mail I've seen
> before.
> 
> I got pcbs back and now want to assemble them.  What is the best way, i.e.
> solder paste to use, heating method, solder bridge removal...?  Most of the
> components are small SMT parts.  The through hole parts I'm fine with.
> 
> Thanks
> 
Lot's of good comments in this thread already.  I've done SMT assembly 
both by hand, and I've experimented with toaster oven reflow.

For a single board, especially for first time checkout, hand soldering 
is just fine, since you can assemble and test a small area at a time 
more easily than when you reflow the whole board.  I find the main 
challenge with any homebrew SMT soldering is getting a small enough 
amount of solder laid down.  It really only takes a tiny amount.

For doing things by hand, get the smallest tip you can round up, or file 
one down. Equip yourself with a syringe of flux as well as a syringe of 
solder, and some of the smallest solder braid you can find.  If you live 
in bifocalville like me, a microscope is nice.  For two-pad parts, use a 
toothpick or tweezer to hold it down while heating the first pad, then 
then solder the second pad without any clamping of the part in order to 
avoid mechanical stresses.

For TQFP's, apply a stripe of solder across all the pads, and tack 
solder just two pins on opposite corners.  After you are happy with the 
alignment you can solder the rest down.  Probably you will have bridges, 
which is easily handled with flux and solder wick.

Hand soldering SMT is tedious, but not difficult.

-dave


_______________________________________________
geda-user mailing list
geda-user@xxxxxxxxxxxxxx
http://www.seul.org/cgi-bin/mailman/listinfo/geda-user