Chris Loiacono wrote:
> Just to add a bit..
> The solder balls indicate a few possible things:
> Either there was excess paste used;
> or all the surfaces never reached and stayed at the minimum reflow
> temp for long enough time;
> or the heat ramp was too sharp and the flux was not given time enough
> to activate.
>
> The silver content does call for a bit more precision in balancing
> the time phases of the process, but with generic 63/37 paste, it's
> not as hairy and is harder to damage anything. Starting with silver
> content in the paste is not a good idea IMHO.
>
> When following the paste maker's process curve for times & temps, I
> have never had soldr balls or a mess of any kind.
>
> I suggest that the entire process needs to be controlled to get
> consistent results - ramp-up, flow, and cool.
>
> Then again, the new Salton Toaster-oven my wife bought recently is
> only capable of under-cooking or burning everything from white bread
> to pumpernickle bagels....so perhaps you have already out-achieved
> the rest of the crew there..


Solder paste deposited out of pads can melt and form small balls that can
stick to the board solder mask paint, but not much, normally you can remo=
ve
them just by touching.   Nothing that a good brush and alcohol 91=B0 can'=
t
remove.

Other than that, please take a look at the recent webpage I put together
about Home SMT Baking:
http://www.ustr.net/smt/index.htm

Cheers,
Wagner.

--
http://www.piclist.com hint: The PICList is archived three different
ways.  See http://www.piclist.com/#archives for details.