Homebrew PCBs

> Woods metal is an alloy of tin-lead-bismuth-cadmium. Hmm, low 
> temperature solder. I suppose that is one way of tinning your 
> boards :-)
> 
> Les


Unless you pass too many amps thru it!

A quick rummage around the 'net turned up Wood's metal is 50% bismuth, 26.7%
lead, 13.3% tin, 10% cadmium by weight.  I don't think that's RoHS
compatible.  It melts at 70C, not 50C as I thought.  Someone once told me
that when pointing out it was used in fire sprinkers.  Might have been a
different alloy.

However, there's Field's metal, 60C melting point and none of the nasty
stuff, being 32.5% bismuth, 51% indium, 16.5% tin by weight.

There's a bloke on eBay selling a 58% Bismuth, 42% tin alloy, melts at 290F.
That's a bit high.

Years ago I turned down the chance to buy a large chunk of Field's metal,
dang.  It comes in handy for casting and weird machining tricks.  To machine
something thin, funny shaped, delicate or otherwise annoying, you cast it
into the Field's metal, machine it, then melt it off.  Since it's supported
by the other metal, the piece you're machining doesn't get damaged.

Tony