Posted by
Don Wilhelm-3 on
Jun 24, 2005; 7:39pm
URL: http://elecraft.85.s1.nabble.com/Your-solder-may-be-no-clean-tp379721p379723.html
I checked the referenced link, and it contains the following statement: "The
eutectic point is the point at which the liquid phase borders directly on
the solid ? + ? phase, representing the minimum melting temperature of any
possible alloy of ? and ?."
As I read that the liquid phase BORDERS on the solid phase, it certainly
says to me that the plastic phase is absent (and that is the most important
point for soldering IMHO). The fact that this also represents the lowest
possible temperature for solidifacation also is true, but not the main
emphasis for a soldering application - we usually use a higher temperature
than the absolute minimum required.
73,
Don W3FPR
> -----Original Message-----
>
> Jerry,
>
> Thanks for the brief explanation of why the NASA solder specifications
> are what they are, and the explanation of eutectic.
>
> If anyone wants to know more about it,
>
http://en.wikipedia.org/wiki/Eutectic does a fair job, and includes a
> phase diagram and is a good reference.
>
> <snip>
> >There seems to be an opinion regarding solder that "eutectic"
> means the ability to go from a liquid state to a solid state
> without passing through a plastic state..."Eutectic" means that
> the ratio of the base metals of the alloy are formulated to give
> the lowest possible point of solidification, usually lower than
> the point of any of the base metals used, and has nothing to with
> the presence or absence of a plastic state...
> >
>
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