[sdiy] Lead-free DIY

[karl dalen]

 >have, higher soldering
> > temperatures wich stresses everything!! Urgh! 
> 
> Yeah, ok.
> 
> How about this then (if we could wish): Sn-Cu-Ag platings and Sn-Bi solder.
> Sn-Cu-Ag plating would not obscure traditional Sn-Pb or Sn-Pb-Ag solders and
> it
> will mixture well with Sn-Bi (to the best of my knowledge). For both kinds of
> solders the Sn-Cu-Ag would quickly disolve into the Sn-Pb, Sn-Pb-Ag or Sn-Bi
> solder.

Im not dubthing into what you say, im only saying that it depends
on the % mixture of the components that maks the alloy, for instance
you say Sn-Cu-AG thats what i use when i hard solder copper to copper
or brass to copper or brass to brass with a blow torch using butane
propane or typical camping cocking gas! No, not fart gas, that type 
of gas are to violent! :-) You cant fart into a bucket and use it!

Sn-Cu-Ag solder pins are also known as the plumber solder when they
solder copper plumbing in houses the problem with that mixture is 
its made for at least 500c deg, the Cu content is very high and 
when cooled after soldering becomes quite hard.

Otherwise your argument are most likely valid!

>The assumption being that the plating content of the final solder
>joint is relatively low. The Cu trace will be noticeable, but should not
>increase the level very much. It would be interesting to know if Cu-Bi forms
>any strange (fragile) mixtures as the solder cools off.

Its well known in metalurgy that heating of hardened (anneled)
materials softem them up a terrible lot, for instance i had a piece
hardened aluminium here, quite hard when heated it turned so soft 
that i could bend it with my fingers. Most pure copper plates does 
the same in various degrees, however most brass mixtures keeps its
stiffness, brass stiffnes depends on the amaout of zink. The more 
zink the stiffer-harder the brass alloy. 

Bi for instance, Bi metal is soft, heavy, brittle, and silvery white
with a pinkish tinge. It melts at 271°C (520F), has a density of 
10.067 grams per cubic centimeter on melting point, expands by
3.32% on solidification, and boils at 1560°C (2840F). Its atomic
number is 83 and the atomic weight 209. It has the lowest thermal
conductivity of all metals, except mercury, while its electrical
conductivity is greater in the solid than in the liquid state.

Bismuth combines with one or several elements such as antimony, 
cadmium, indium, gallium, lead, tin... to form alloys melting as
low as at 20°C (68°F).

Because it expands on solidification, it can be dosed to produce 
dimensionally stable alloys. As a rule of thumb, alloys with more 
than 55% Bi expand, those with less than 48% contract. Mixtures 
in the remaining gap being dimensionally stable.

Furthermore, the next generation of electrical contact material is 
based on Silver-Bismuth compositions suitable for the building and
the automotive sectors because they resist wear, do not weld or
produce arcing under heavy loads.

> Some of this should be a matter of digging in the ref-books.
> > > Where's my Metalurgy-DIY handbook when I need it?
> > Not where we want it to be!!
> Sadly not :(
Well i dont even have one but i shurly wish i could find a quality one
much like a cook book, eg, take this, blend with this, and get this alloy!  

Reg
KD