Jim,

The first thing I would do to help determine why the terminations are discoloring would be to do an XRF measurement of the termination on one of the capacitors to see what the terminal metallization is and compare it to what the capacitor data sheet says it is supposed to be.

Regards,
George
George M. Wenger
Senior Principal Reliability / FMA Engineer
Andrew Corporation - Wireless Network Solutions
40 Technology Drive, Warren, NJ 07059
(908) 546-4531 Office (732) 309-8964 Mobile
E-mail: [log in to unmask]

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Jim West
Sent: Tuesday, March 06, 2012 1:03 PM
To: [log in to unmask]
Subject: [TN] Capacitors end termination discolored.

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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