Suggestions for VT103?
cclist at sydex.com
Mon Dec 29 11:56:26 CST 2008
On 29 Dec 2008 at 8:57, Sridhar Ayengar wrote:
> It's not the lower melting point. It's that the mixture is eutectic.
There's a lot of misconception about what solder alloys are really
The characteristics of various tin/lead ratios are very useful. I
work a lot soldering sheet brass. Normally, I work with 50/50 alloy
because of its large plastic range and its ability to fill gaps and
be tooled while cooling. But if I'm working with something that
requires a joint to solidify almost immediately from the liquid state
(eutectic), it'll be a 63/37 alloy. Melting point isn't a major
issue as I'm working with an acetylene torch. 60/40 gives you a bit
of plastic time before solidifying, but not much.
If I were soldering PCBs, I'd want the eutectic alloy--liquid or
solid, with virtually no plastic phase in between.
Plumbers and radiator repair shops use the 50/50 alloy because it can
be tooled while cooling. (In theory, the term should be "plumbers
used to use" since lead-bearing solder for plumbing now violates code
in the USA. But I've yet to see a plumber who doesn't keep a couple
of rolls of 50/50 squirreled away for the tough jobs). The tradeoff
is that the workpiece must be solidly clamped or otherwise fixed so
that it doesn't move while the solder is solidifying.
This control of state-change characteristics is one thing for me that
sets lead-bearing solders apart from the RoHS pack.
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