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Date: | Fri, 11 Jul 97 09:12:50 cst |
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Hi Christian -
We do a bunch of SEM-EDX (Energy Dispersive Xray) as a method of
getting a snapshot of what is happening. The EDX technique is good to
about 0.5 atomic weight percent and can look at small areas. Using the
Auger microscopy techniques you can get down to 0.1 atomic % and a
much smaller analysis region but not everyone has an Auger sitting on
their desk. There are other electron microscopy techniques (ESCA,
SIMS,etc.) but you really just want to get a general idea of what is
happening with the solder joint metallurgical composition and not do a
exhaustive investigation - the simpler SEM techniques will give you
that information. My preference is to look at a scan/raster area that
includes the whole solder joint first and then do point scan/rasters
on solder joint areas that look to be segregated. Based on these
general results you can decide if additional solder joint reliability
testing is warranted. As for solder joint reliability, thermal cycling
with continuous electrical monitoring of the solder joints has worked
well for me. Good luck.
Dave Hillman
Rockwell Collins
[log in to unmask]
______________________________ Reply Separator _________________________________
Subject: Re: Solder compatibility
Author: [log in to unmask] at ccmgw1
Date: 7/11/97 8:25 AM
Dave,
in your reply you recommend the use of Scanning Electron Microscopy analysis
techniques. As far as I know there are some methods available - single point,
areal
and others, depending on the required analysis resolution. Talking about a
final
composition of Sn/Pb/Ag (even some small zones only) what analysis technique
would be recommendable ? Furthermore, any recommendations for Solder Joint
Reliability Testing?
Regards,
Christian
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