On 30/01/2017 07:32,
olds...@tubes.com wrote:
> One other thing. I am not finding any 50-50 or 60-40 lead tin rosin core
> solder anymore. At least not in the stores. I do not plan to serve
> anyone dinner on the underside of a chassis, so I'm not worried about
> getting lead poisoning. But apparently the government must think we eat
> off of our electronics and have banned the old lead based solder.
>
> Since I will be removing old caps, soldered with lead-tin solder,
> shouldn't I be using lead-tin solder to replace the parts? Or will the
> new solder (whatever it's made of), mix properly with the old lead based
> stuff? (I dont want to create some sort of dialectric corrosion issues).
> [Even with a desoldering bulb and wicking, not 100% of the lead is ever
> removed]. Not to mention that I have heard that some (or all) of these
> new solders require a lot more heat, which can damage the components
> while soldering.
You can still buy leaded solder, even in Europe where it is not allowed
in new electronics that is sold, but can still legally be used to repair
things that were built before 2006. You can also use it to make new
things in Europe if you do not "place them on the market".
The solder with 60% lead is not even very nice to use, because it spends
a lot of time in a "mushy" state as it is cooling. I think they only
used 60% lead in old appliances because lead is cheaper than tin. The
eutectic alloy with 37% lead is much better because it goes from fully
liquid to being fully solid over a small range of temperature, but is
slightly more expensive due to the higher price of tin.
Some of the lead-free solders are actually not bad to use, for example
96SC alloy from Multicore. The melting point is a bit higher than
tin-lead eutectic but probably not much different from the 60% lead
alloy that you wanted. The high melting point would only really be a
problem if you are desoldering components from plated-through holes in a
multilayer board with several ground planes buried within it, and that
sounds unlikely for your vintage electronics. The only problem that I
have with the 96SC alloy is that it is expensive, perhaps partly due to
the 3.8% silver content.
The area around the wet sponge used for cleaning the soldering iron
usually gets covered in tiny solder particles and dust, that get on the
carpet etc. When soldering at home the main risk is probably if you have
a young child in your family of the age where they crawl on the floor
eating dirt, and they eat some lead dust. A blood concentration of lead
that is increased by 50 parts per billion is correlated with an IQ that
is 10 to 20 points lower. If you do the calculations, 50 parts per
billion is not much.
http://oehha.ca.gov/media/goodmangilmanlead.pdf
If you are working on old equipment then regardless of whether you use
leaded solder wire or not, the solder droplets that end up on your
sponge and on the bench around it will contain lead, so it is best to
wipe it up carefully and keep it out of living areas of your house.