[sdiy] Solder paste and toaster ovens

[Tim Parkhurst]

Hey Peter, 

Actually, I've done solder paste reflow with a hot air gun. It worked very
well! Basically, just keep the nozzle moving, so that you gradually heat up
the board. If the heat gun has a concentrating nozzle, I would take it off
(so that you get a larger warm air pattern). It's easy to see once you've
reached the right temp because you can watch the solder paste change states.
Once the paste flows and you get a nice smooth solder joint, keep the nozzle
moving and back it off slowly. This is so you don't rapidly heat or cool the
board (the thermal shock can be bad for other solder joints on the board).
Heat up the board over a period of at least 30 seconds, and let it gradually
cool over the same amount of time. I was at a client's once (back when I
used to install SMT pick and place machines), when their reflow oven broke
down. We completed six boards (each about 6" x 6" with over 100 components)
by using a heat gun. I held the gun and had two guys wearing hi temp gloves
hold the boards. All six boards worked perfectly!


Tim (you can pry my heat gun from my cold, dead hands) Servo

"Imagination is more important than knowledge." - Albert Einstein




> -----Original Message-----
> From: Peter Grenader [mailto:peter at buzzclick-music.com]
> Sent: Thursday, March 31, 2005 8:27 AM
> To: synth-diy at dropmix.xs4all.nl
> Subject: [sdiy] Solder paste and toaster ovens
> 
> A while back someone here spoke about flowing solder paste in a toaster
> oven.
> 
> Anyone do this?  Would a heat gun work better or as well?  I'd like to
avoid
> putting whatever particulates the solder paste may spew into my toaster
oven
> so my bagels don't become carcinogenic!
> 
> My situation:
> 
> In a nutshell, I may have to solder an expensive NPN pair in a TO-71 can
to
> a board using solder paste so that I can get it down close enough to the
> board surface soo it rests upon a chip resistor. Basocally - REAL low to
the
> board. Problem is, when the tranny is down that far I can't get to the
leads
> to solder them (non plated through holes).  OK - so...I thought I'd use
> solder paste.  Problem is, if any of the leads of the tranny don't flow
with
> the paste, then I'm screwed because it's going to be impossible to get to
in
> there to do touch up.  THe secret of couse is to buzz it out before I clip
> the leads in case I have to back up connections withwire on the other side
> of the board, but of course I'd like to avoid that if possible.
> 
> \any help would be appreciated.
> 
> - P
> 
> 
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