I have to agree with Inge that I did not see discoloration like I was
expecting.   Usually the color is more bluish when heat related oven
damage is the cause (generally speaking).

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Inge Hernefjord
Sent: Wednesday, March 07, 2012 9:52 AM
To: [log in to unmask]
Subject: Re: [TN] Capacitors end termination discolored.

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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