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January 2001

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Subject:
From:
"Ingemar Hernefjord (EMW)" <[log in to unmask]>
Reply To:
TechNet E-Mail Forum.
Date:
Thu, 18 Jan 2001 15:52:39 +0100
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text/plain (58 lines)
Evening here, Lisa,
your name sounds very scandic. Yes please, send me image, maybe we have same problems, who knows. We use a 560 and smaller, and get sometimes strange joints with electrical opens or even worse. The solderings may work for one year or two or even more, but as we have seen rare intermetallics between balls and PCB land nickel, we think it's advisable to keep an eye on it and learn more.

Ingemar Hernefjord
Ericsson Microwave Systems

-----Original Message-----
From: Lisa Anderson [mailto:[log in to unmask]]
Sent: den 18 januari 2001 14:06
To: [log in to unmask]
Subject: [TN] PGBA Cold solder joints


Good morning to all!  Question for those with
experience in the BGA arena .. lately, we have noticed
cold solder joints on the outermost row of balls of a
357 Motorola PBGA package.  The problem is not found
at any testing stage since the ball and reflowed paste
are making sufficient contact; it shows up later
after, what is assumed, oxidation forms.  At present,
we are suspecting 1) coplanarity issues, 2) activation
of the flux too early in the reflow soak stage, 3)
cupping ("potato chipping") of the device as it is
processed through the reflow oven.  Has anyone out
there experienced this problem?  TIF file attached for
viewing pleasure.

Many thanks in advance for your help,

Lisa Anderson

Note: if file can not be viewed, send me a note.

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