Hi TDK!

If you hadn't read my previous thread from this saga, you wouldn't have known
that these solderballs occurred during wave solder, not SMT reflow as you
suggested.

I always make sure my pre-heat ramp isn't too steep while driving off the
volatiles in the paste, not only to prevent solderballs, but to make sure I'm not
killing my flux too soon, as well as reducing thermal shock.

-Steve Gregory-

> I recall from my early intro into SMT that solder balls are caused by the
> rapid melting of the SMT paste during reflow. It is a violent transformation
> that literally causes the solder paste to explode as it becomes a liquid,
> causing a splattering of molten solder.
>
> The way around that was to do a careful preheat for a certain temperature &
> time ( the 2 of which I don't know - only a reflow technician would have the
> historical & empirical history to tailor these as they change with different
> pastes, etc. ). This causes the extra liquid resins in the paste to
> evaporate & thus result in a more subdued reflow process, eliminating the
> splattering of molten solder which, when solidyfing, results in "Solder
> Balls".
>
> Am I somewhat on track here or way off ???
>
> This intro was well over 10+ years ago.
>
> Regards
> TDK
>


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