Effects of vibration on capacitors

[Rich Grise]

Watson A. Name wrote:

And what i would really like to know more about is what is mentioned in
"commercial EIA Class 2 and Class 3 dielectric, such as X7R, X5R, X8R,
Y5V, Y5U, Z5U, etc." Like, what's this "EIA Class 2 and Class 3
dielectric, such as X7R, X5R, X8R, Y5V, Y5U, Z5U, etc."?? Where can I
find more detailed info? Or is ths another high-priced EIA document
that's not available online? And no one is willing to go into detail
about the subject?

http://www.google.com/search?q=ceramic+dielectric+comparison+chart&btnG=Search
First Hit:
http://www.avxcorp.com/docs/techinfo/dielectr.pdf



Have Fun!
Rich

 

[Rich Grise]

On Sun, 14 Nov 2004 07:27:45 -0800, Watson A.Name - "Watt Sun, the Dark
Remover" wrote:
On Sun, 14 Nov 2004 07:27:45 -0800, Watson A.Name - "Watt Sun, the Dark

"Terry Given" <my_name@ieee.org> wrote in message
High-dielectric constant ceramics certainly pick up vibration long
before anything breaks, and no matter how much you scold them they
do
not stop.

Yet another reason to avoid the poxy things. Z5U, Y5V = shite.

Avoid, how? I come across a lot of caps tha aren't marked as such, all
they have is '104' marked on them, ferinstance. How do I know if
they're "shite"? And then there's the problem of how to avoid them, if
a replacment has other serious disadvantages, such as being much bigger?

That's why I want to know more aout the different grades of caps, and
what those designations mean. That way, I can make more intelligent
decisions on whether or not they're suitable for a certain application,
and not just make an uninformed generalization and claim they're all
"shite".

Z5U and Y5V are very cheap ceramic dielectrics that pack a lot of
picofarads into a relatively small package, at the cost of abysmal
tolerance and stability specs, and possibly ESR - but two out of
three of these are irrelevant for decoupling, and the third might
actually enhance it, by lowering the Q of the decoupling cap,
tending towards a snubber sort of thing. X7R, I guess, is one of
the high-stability ones, either by tolerance or tempco; NPO means
negative-positve-Zero (tempco), which, for your convenience, they
symbolize with '0', which everybody reads as 'O' anyway.

Any more than that, I'd have to recommend to you to Our Friend,
Google The Wise, for charts and stuff.

If you'd like to hear from the bench tech in me, I'd use polyester
or some very expensive thing like that if I wanted to get 1% out
of a 555. For decoupling, use the cheapest ceramics you can get,
and one cap per chip is not too many. And I would try to sprinkle
tantalums about, 1 - 10 uF, and one 100uF aluminum honker at the
board's power entry point. For two rails, of course, double this,
observing polarity.

For RF, I've heard great things about silvered mica, but that
might just be my inner museum bringing them up because all those
millennia ago that was the best they could come up with.

And, of course, as usual, (all together now,) It Depends.

As far as microphonics. Since I am as good as totally clueless
about that compared to the information the other posters have
been kind enough to share, I'll let that go other than to say
that I understand the principle, but I've never encountered
microphonics from any capacitor that I've noticed at the time.
I haven't ever gone _looking_ for them, and whenever I've
encountered microphonics, there's always been a coil or some
component flapping in the breeze or something, to account for
it.

Try shouting at your All-American-Five and see if your voice
comes out the speaker!

Hope This Helps!
Rich

 

[David Harper]

"Roger Hamlett" <rogerspamignored@ttelmah.demon.co.uk> wrote in message news:<hsnmd.54$Zf4.34@newsfe6-win.ntli.net>...

"David Harper" <dave.harper@gmail.com> wrote in message
news:364fd697.0411120525.25f3d961@posting.google.com...
Does anyone know how severely vibration can affect a capacitor's
ability to regulate voltage? (i.e. how much the voltage can deviate
as a function of vibration) What types of caps are better at
regulating voltage under high vibration?

Thanks in advance!
Dave
Lots of comments so far about the various types of component, and the
effects. However I wonder if you could be 'ingenious', and make the
effects cancel?. If (for instance), you arranged four capacitors, in a
tight circle, each rotated 90 degrees to the next, and mechanically
coupled them together (epoxy), and electrically connected them in
parallel, then presumably (within the limits of the mechanical propogation
speed of the actual vibration), the effects would largely cancel. It might
be worth considering, if the capacitor sizes required, were larger than
available in types that have little response to vibration.

Best Wishes

I guessing that it would not work much better than 4 caps in parallel
with no specific orientation... your idea assumes that the vibration
affects capacitors arranged in different angles in opposite manners.
It may affect them identically. Secondly, the overall effects could
change significantly depending on the frequency of vibration.

Dave

 

[Roger Hamlett]

"David Harper" <dave.harper@gmail.com> wrote in message
news:364fd697.0411170939.45ebc4a5@posting.google.com...

"Roger Hamlett" <rogerspamignored@ttelmah.demon.co.uk> wrote in message
news:<hsnmd.54$Zf4.34@newsfe6-win.ntli.net>...
"David Harper" <dave.harper@gmail.com> wrote in message
news:364fd697.0411120525.25f3d961@posting.google.com...
Does anyone know how severely vibration can affect a capacitor's
ability to regulate voltage? (i.e. how much the voltage can deviate
as a function of vibration) What types of caps are better at
regulating voltage under high vibration?

Thanks in advance!
Dave
Lots of comments so far about the various types of component, and the
effects. However I wonder if you could be 'ingenious', and make the
effects cancel?. If (for instance), you arranged four capacitors, in a
tight circle, each rotated 90 degrees to the next, and mechanically
coupled them together (epoxy), and electrically connected them in
parallel, then presumably (within the limits of the mechanical
propogation
speed of the actual vibration), the effects would largely cancel. It
might
be worth considering, if the capacitor sizes required, were larger
than
available in types that have little response to vibration.

Best Wishes

I guessing that it would not work much better than 4 caps in parallel
with no specific orientation... your idea assumes that the vibration
affects capacitors arranged in different angles in opposite manners.
It may affect them identically. Secondly, the overall effects could
change significantly depending on the frequency of vibration.
Yes. It was a 'thought exercise', but with some capacitors exhibiting

piezo effects, might be worth considering.

Best Wishes

 

[Terry Given]

Tim Wescott wrote:

Dan Major wrote:

dave.harper@gmail.com (David Harper) wrote in
news:364fd697.0411120525.25f3d961@posting.google.com:


Does anyone know how severely vibration can affect a capacitor's
ability to regulate voltage? (i.e. how much the voltage can deviate
as a function of vibration) What types of caps are better at
regulating voltage under high vibration?


Caps and resisters should not be affected by vibration. They are
monolythic (solid) devices. OK, "should not be affected..." up to a
point. If you get vibration that causes g forces great enough to
cause mechanical breakdown of the physical packaging, *then* the
values will change. Other components, however, will be affected
because they are either mechanical in function (crystals), or are such
that the shape can be easily changed (coils, etc.). I suppose if the
components were surface mounted on a circuit board that was flexible
enough, and the vibrations caused the components to bend or otherwise
change shape *then* caps and resistors could change value.

High-dielectric constant ceramics certainly pick up vibration long
before anything breaks, and no matter how much you scold them they do
not stop.

Yet another reason to avoid the poxy things. Z5U, Y5V = shite.

Cheers
Terry