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From: Fred Bloggs
User-Agent: Mozilla/5.0 (Windows; U; Win 9x 4.90; en-US; rv:1.0.1) Gecko/20020823 Netscape/7.0
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Subject: Re: Ceramic Capacitors
Date: Thu, 26 Sep 2002 12:44:46 GMT
NNTP-Posting-Date: Thu, 26 Sep 2002 05:44:46 PDT
Organization: EarthLink Inc. -- http://www.EarthLink.net
> I just found out that ceramic capacitors can exibit a piezoelectric effect
> that in presence of mechanical vibrations on a board, can produce electrical
> noise on a line that the capacitor is suppose to decouple...
> The phenomenon may not be negligeable on big size surface mount caps.
> The paper said "some" ceramic capacitor..
Can you cite this paper? And I am perplexed by the statement that NP0
dielectric does not exhibit piezoelectric effects since it is the same
material in a blend of N-egative and P-ositive tempco to yield 0.
> Does anyone have any information on precisely what kind of ceramic capacitor
> would particularly exibit this behavior ? ( NPO, X7R, X5R, Y5V, Z5U ... ? )
> Searches onthe net didn't bring anything relevant.
Even if it does, the bulk component continues to exhibit capacitance
which will attenuate the voltage greatly- probably because of the large
effective output impedance of the small region producing the emf.
Maybe you can use a microphonics damper as shown here:
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