On Wednesday 17 August 2005 10:43 am, derekhawkins wrote:
> > How much are you thinning the solder paste before you paint it on? It
> > sounds like you're really thinning it down quite a bit.
>
> The reason for thinning is not to prevent solder forming where there is
> no copper. You thin to get an even layer of paste without ridges or
> brush marks that will cause some places to have too much solder. Areas
> without copper will be filled with tiny discrete balls of solder that
> wash off quite easily.
>
> A new jar of paste may be so moist that no thinning at all is required.
> Whatever, thinning will usually consist of just adding a few drops of
> water at the top of the paste in the jar or wetting the brush
> occasionally. Sort of like painting with solid water paints.
>
> I don't have many pictures of the process but here is a shot of what to
> expect if too much paste is used....Raised rings around would be holes
> in pads and raised tracks and pads (some may prefer this);
>
> http://www.pbase.com/eldata/image/47810059/original
Interesting pic, that's _still_ loading on this dialup connection. Must be
pretty big!
> Caution:
> Depending on paste used, it may contain lead and/or an acidic flux.
I was of the impression from earlier posts in this thread that the stuff you
were talking about was lead-free, which is something I'd rather avoid if
possible. Acidic flux strikes me as something else to avoid, as well.
And this stuff is available as plumbing supplies? Seems to me to be a whole
lot easier to use than the stuff I've seen talked about in the context of
surface-mount, where it has a limited lifespan, requires refrigeration (!),
etc.
Wonder why I haven't heard of this before? :-)