Have you modified reflow profile? To be higher peak or slower cool down?
Are these larger devices than the norm? (giving larger thermal
mass/inertia).
With silver in the joints those conditions can give rise to a coarser grain
structure and on the surface this can present as roughness = dulling.
So far as IM layer is concerned, what is the age of the parts? In these
straightened times it is possible the parts have been on someone's shelf a
little longer than normal.
Regards
Mike Fenner
Indium Corporation
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Newland, Scott
Sent: Tuesday, January 13, 2009 7:21 PM
To: [log in to unmask]
Subject: [TN] Dull and Grainy Leaded Solder Joints
We are suddenly seeing a rash of dull and grainy solder joints on SMT
inductors that use silver-palladium-platinum-glass frit terminations.
Otherwise the exterior of the joint looks good. The terminations as
supplied have no leaded or lead free solder or tin finish, just the
glass frit. In cross section the joint is also unique in that there is
no real IM layer and the grain structure near the joint is a bit odd.
The solder joints are fully re-flowed. All the other solder joints on
the CCA look good with no indication of solder process issues.
The vendor claims they have been supplying this type of termination for
years and nothing has changed, also this issue has just sprung up in the
last couple of months.
As far as we can tell the joints look different, but reliable.
Any suggestions or comments?
Scott Newland
Chief Mechanical Engineer - Fighter Enterprise
Harris GCSD
321 768 4272 (W)
321 720 1756 (C)
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