The Cyber-Spy.Com Usenet Archive Feeds Directly
From The Open And Publicly Available Newsgroup
This Group And Thousands Of Others Are Available
On Most IS NNTP News Servers On Port 119.
Cyber-Spy.Com Is NOT Responsible For Any Topic,
Opinions Or Content Posted To This Or Any Other
Newsgroup. This Web Archive Of The Newsgroup And
Posts Are For Informational Purposes Only.
Subject: Re: Ceramic Capacitors
Date: Fri, 27 Sep 2002 07:56:52 -0400
X-Newsreader: Microsoft Outlook Express 6.00.2600.0000
"Fred Bloggs" wrote in message
> dhrm77 wrote:
> > I just found out that ceramic capacitors can exibit a piezoelectric
> > that in presence of mechanical vibrations on a board, can produce
> > 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.
So far I have found 2 papers :
The first was part of the datasheet for the LT1761 :
http://www.linear-tech.com/pdf/1761fa.pdf page 14
The other is a comparison of multilayer ceramic and tantalum capacitors :
http://www.avxcorp.com/docs/techinfo/mlc-tant.pdf page 4
None of those 2 are any close to being thorough on the subject.
None actually addressed NPO (COG) caps.
Any more information would be appreciated.
> > Does anyone have any information on precisely what kind of ceramic
> > 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:
Go Back To The Cyber-Spy.Com
Usenet Web Archive Index Of
The sci.electronics.design Newsgroup