Jason

Some manufacturers use water-soluble flux of the amino acid-hydrochloride/amine
hydrochloride types for tinning, often with very perfunctory washing afterwards. Bought
in tinned wire is often zinc-chloride/hydrochloric acid fluxed before passing through
the tinning bath and then simply wiped between a damp, folded skin (sometimes slightly
greasy) as it leaves the tinning bath. Others, but not all, do pass it through a couple
of (usually static) water baths as well.

Do not be surprised at quite high chloride ion levels on leads, but it is not possible
to say whether they come from component manufacturers or their suppliers. If the
process includes tinning on nickel, it is difficult to tin without some chlorides.

This is one reason why "no-clean" soldering does not offer the expected reliability,
when no control of incoming components is done.

Brian

"Jason Larson, AScT" wrote:

> Hi Technet, I have a question for those that are involved with component
> manufacturing.
>
> What type of flux is used for preparing leads for tinning? Also is there
> anywhere that chlorine is used in this process? Where would chlorine come
> from if not from the manufacture?
>
> We analyzed some of our raw goods with a SEM and noticed that there was
> chlorine present in the junction of diodes and also on the leads by the
> glass / slug interface
>
> Thanks
> Jason
>
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