Ed,
Unfortunately access was denied but on a general note metal particles on
MLCC surfaces are some what common and are due to several factors. First,
typically these parts are vibratory bowl fed to a tape a reel machine for
reeling and depending on vibration intensity and chip size, parts
terminations will mark the bodies of other parts. Second, surface roughness
plays a significant factor in termination marking. From a practical stand
point this marking becomes less desirable as operating voltages increase,
spacing shrinks and if moisture, contamination etc. is present to promote
nasties to form between metal marks between MLCC and PWB.

John

At 08:21 AM 6/3/02 -0700, you wrote:
>Fellow Technetters,
>
>I recently found extraneous metal on the surface of several MLCCs on an
>assembly.  I examined stock parts and found this condition pre-existed on
>the stock caps (tape & reel).  These caps have pure tin terminations.  There
>is a picture of this condition at the link below ...
>
>http://www.eskimo.com/~ehare/MetOnCap.bmp
>
>What is your opinion of the acceptability of this condition?
>
>What might be the root cause?
>
>Are there any specifications that address this issue?
>
>Best regards,
>Ed
>--
>
>                SEM Lab, Inc.
>       Scanning Electron Microscopy
>            and Failure Analysis
>                Snohomish, WA
>             Ph. (425)335-4400
>              Fax  (603)658-4519
>           http://www.semlab.com
>
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