Hi Roger,
In addition to what Dave has said, I'd recommend to do planar SEM/EDS analysis of the "de-wetted" areas (to see what happened to the board finish and what has been "formed"). On top of that, I'd pull off one of the lead and do SEM/EDS on both surfaces (bottom side of the lead and top of the pad).
Vladimir
Vladimir Igoshev,
Research in Motion
-----Original Message-----
From: TechNet [mailto:[log in to unmask]]On Behalf Of David D. Hillman
Sent: Thursday, January 06, 2005 1:39 PM
To: [log in to unmask]
Subject: Re: [TN] Solder Joint Failures after Short-term Vibration
Hi Roger! I recommend having a cross-section completed so you can get a
look at the solder joint/component lead interface to determine the quality
of the solder joint interface/structure. Good Luck.
Dave Hillman
Rockwell Collins
[log in to unmask]
Roger Stoops
<Roger_Stoops@TRI
MBLE.COM> To
Sent by: TechNet [log in to unmask]
<[log in to unmask]> cc
Subject
01/06/2005 12:19 [TN] Solder Joint Failures after
PM Short-term Vibration
Please respond to
TechNet E-Mail
Forum
<[log in to unmask]>
; Please respond
to
Roger Stoops
<Roger_Stoops@TRI
MBLE.COM>
Hello all,
We are having an ongoing problem with solder joint failures on a 144-pin
PQFP processor, after short-term vibration. The board layout and mechanical
mounting apparatus were designed with vibration in mind, and have passed
vibration testing in the past. The same processor is used on a dozen other
assemblies, none of which have this problem.
The solder joints appear to exhibit dewetting, although there is a toe and
heel fillet. The heel fillet is unusually large, and the top of the PQFP
lead has a grainy appearance instead of a matte or shiny appearance. Some
leads can be pushed off the solder joint with very little pressure.
Sn62Pb36Ag2 solder is being used, and our EMS provider continues to claim
that boards meet IPC-A-610 class 2 requirements.
Any ideas as to what may be causing solder joint failures?
Also, any suggestions or recommendations (preferred) for a test house to
provide x-ray, microsection and composition analysis?
TIA & Best Regards,
Roger M. Stoops, CID+
Trimble Navigation Ltd., Dayton, OH, USA
Ph: +01 937.245.5288
Fax: +01 937.233.7511
Oh, and BTW, changing EMS providers is not an option...
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