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September 2004

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Subject:
From:
"Dehoyos, Ramon" <[log in to unmask]>
Reply To:
TechNet E-Mail Forum <[log in to unmask]>, Dehoyos, Ramon
Date:
Fri, 10 Sep 2004 09:36:57 -0700
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        Hi Gaby:
        Solder ball are potential source for shorts. Perhaps there is a need to remove the part and wick up the solder balls and reinstall or replace the part.
        Good luck,
        Ramon

-----Original Message-----
From: TechNet [mailto:[log in to unmask]]On Behalf Of Gabriela Bogdan
Sent: Friday, September 10, 2004 12:24 PM
To: [log in to unmask]
Subject: [TN] Tin plating on leads HELP!!!


Dear friends,
After assembly, on all circuits there was one fine pitch PLCC from a certain vendor which had lots of small solder balls between the leads, even on the solder mask dam between them.
Other PLCC's with the same pitch were clean.
We tried to see the amount of solder balls by X-ray, and found many more behind the leads.
At first we thought that our solder paste was the culprit, but seeing that other components were "normal" , we looked closer to the leads by X-ray, and saw a lot of small voids only along the leads of the bad component, these voids reaching to the upper end of the leads, where the solder paste did  not reach. Visually, the upper part of the leads was very rough.
I suppose that the tin plating of the leads contained additives which epand during soldering, even burst out, and "spit" the molten solder all around.
If this is the case,how could I reject such components during incoming inspection?
Should I do a solderability test for each batch on a printed ceramic plate?
Gaby

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