The photos do not show any discoloration. Did you select the right
components? I have seen discoloration of many epoxy covered components. The
analysis is usually this:
alt.1  deviation in the component manufacturer's process
alt. 2 overheat due to excessive heat in the soldering process, especially
with IR-lamps
alt. 3 overheat due to excessive current
alt. 4 natural discoloration of epoxy body over a long time's operation

the reason for most issues occur in the middle section can simply be that
those components were exposed to harder  IR radiation, not unusual with IR
lamp ovens. We left such ovens and use VP.

Inge



On 6 March 2012 19:02, Jim West <[log in to unmask]> wrote:

> Hi all,
>
> Take a look at the photo's at the below links (one shows picture of a new
> cap).  I'm trying to figure out why the end terminations of a tantalum
> capacitor (C37 and C38) are coming out of the reflow discolored.  In our
> process, the middle boards of our panel have the discolored terminations.
>  The boards on the outside of the panel are all fine.  I think it's a heat
> related issue, but I don't know why only the middle boards are affected.
>  All the solder joints are looking fine as well (even on the discolored
> terminations).
>
> Any thoughts as to what might be happening?  In your opinion, would your
> reject these?
>
> http://stevezeva.homestead.com/Discolored_Tant.jpg
>
> http://stevezeva.homestead.com/New_Tant.jpg
>
> Jim West
>
>
>
>
>
>
>
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