Hi Dale - Do you have any pictures that you can share with the group? A
visual would assist in providing you accurate information.

Dave Hillman
Rockwell Collins
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"Hart, Dale L CTR USAF AFMC AFRL/RXSA" <[log in to unmask]>
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Subject
[TN] solder joint height








We have been doing a some analysis of cca's for the Air Force consisting
of
SMT.  The visual inspection of the solder joints looks very good all
characteristics above the suggest minimum for class 3 of 610.  The solder
fillets in some instances could be characterized as being robust.  In
cross-sectional analysis however, the solder joint height of the
components
electrical termination above the land has been perhaps 0.025 mm to the
point
of needing a SEM to look at the land-solder-component lead interface.
Closer examination in these areas revealed small cracks in the grain
boundaries.  I used the term grain boundaries because the solder in these
areas do not resemble the colonies observed in the bulk solder of the
fillet.  In some of these instances the land is often deformed in the
shape
of the component lead.



Would these joints although stronger be more susceptible to fatigue or
overload failure?

What are the implications if these cca's are encapsulated?

What suggestions could be offered to the manufacturer?





Dale L. Hart

Universal Technology Corporation (UTC)

Failure Analysis

1270 North Fairfield Road

Dayton, Ohio  45432-2600

(937) 656-9165

Fax (937) 656-4600

Email:  <mailto:[log in to unmask]> [log in to unmask]




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