No, Ioan,
You can't create a resonance circuit that way. The method works with
caps only.
Cracked BGA solder joints...who/what is cracking them? Thought such
problems were very rare nowadays, at least if you are still soldering
with SnPb (our MIL production need not change to leadfree in 10 years).
Inge
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Tempea, Ioan
Sent: den 19 juni 2006 13:48
To: [log in to unmask]
Subject: Re: [TN] Finding cracked capacitors
Inge,
this is very interesting! Would this equipment take care of the cracked
BGA solder joints?
Thanks,
Ioan
-----Original Message-----
From: TechNet [mailto:[log in to unmask]]On Behalf Of Ingemar Hernefjord
(KC/EMW)
Sent: Monday, June 19, 2006 5:58 AM
To: [log in to unmask]
Subject: Re: [TN] Finding cracked capacitors
It may be a little late adding test methods, but I'm curious about what
the reaction will be on my proposal. Years ago, Yves Ousten, Institute
Polytechnic Paris, gathered a number of guys from the universities and
the industry in order to find an acceptable way of finding defect
ceramic capacitors. He based his method on resonance ciruitry, where any
defect cap would deviate from a specified RF resonance signature. He
utilized the generation of elastic waves and piezoelectric effects,
microcracks having an essential influence on these parameters. He has
written a lot about the test method, myself, I have just two reports:
"Improving Reliability of electronic assemblies using early physical and
electrical indicators." and
"Non-destructive detection and localization of defects in multilayer
ceramic capacitors using electromechanical resonances."
"The use of Impedance Spectroscopy, SEM and SAM imaging for early
detection of failures in SMT assemblies."
It seems as the test method calls for skilled RF test engineer and quite
a expensive RF equiment. On the other hand, both these are available at
big companies. We were planning to use Ousten's method, but we have less
need nowadays, as microcracks are rather rare.
Anyone who have used this capacitor test method?
Ingemar Hernefjord
Ericsson Microwave Systems
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