Yes, it could. 
But, so could flux residue.
 

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of James Verrette
Sent: Friday, September 19, 2008 4:23 PM
To: [log in to unmask]
Subject: [TN] Can desoldering and soldering fix a leaky MLCC

I had a case where I was measuring about 100k accross two nets on a PCB
Assembly with an Ohm meter.  I removed a .1uF X7R MLCC SMT 0402 size from
the board and the 100k short went away.  I measured the cap and the ohm
meter and the resistance was OL.  I put the capacitor back on the board and
remeasured the resistance and there was no short.  I looked for obvious
damage on the cap under a microscope, but didn't see anything.
 
Is it possible that desoldering and resoldering by hand could cause a leaky
MLCC to stop leaking?  I am trying to find an explaination for what made the
100k short circuit go away.  The only other expaination is that there was
something under the part that caused leakaget.  The boards are assembled
with no-clean flux, SnPb solder paste.
 
Based on what I have read flex cracks could cause the leakage we saw before
the modification, but could desoldering and soldering cause it to go away?
 
Jim Verrette
Senior Electrical Engineer
 
 
 

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