10V ceramic cap at 95V DC ?

[Adam S]

I was wondering what happens when you put too much voltage across a one
of those low voltage multilayer ceramic capacitors. I took a 2.2uF 10V
X7R in 1206 package, and applied 95V across it and nothing exciting
happened. Leakage settled to 0.5uA after 2 minutes. Even after
disconnecting for 1 minute the terminal voltage was around 60V+. The
only thing I noticed was capacitance had dropped from 2.30uF to 1.85uF
(at 0 VDC bias) after the test. However heating the capacitor with a
soldering iron tip for a second , had restored it to its original 2.30uF.

So what bad things are suppose to happen when you exceed the 10V spec. ?

 

[Uwe Bonnes]

I was wondering what happens when you put too much voltage across a one
of those low voltage multilayer ceramic capacitors. I took a 2.2uF 10V
X7R in 1206 package, and applied 95V across it and nothing exciting
happened. Leakage settled to 0.5uA after 2 minutes. Even after
disconnecting for 1 minute the terminal voltage was around 60V+. The
only thing I noticed was capacitance had dropped from 2.30uF to 1.85uF
(at 0 VDC bias) after the test. However heating the capacitor with a
soldering iron tip for a second , had restored it to its original 2.30uF.

So what bad things are suppose to happen when you exceed the 10V spec. ?

As you have seen
- Polarization gets lost (perhaps recoverable)
and more
- Capacitance at that high voltage drops considerably
- At some point in time or at some higher voltage the part will spark or
something like that

Bye

 

[colin]

I was wondering what happens when you put too much voltage across a one of
those low voltage multilayer ceramic capacitors. I took a 2.2uF 10V X7R in
1206 package, and applied 95V across it and nothing exciting happened.
Leakage settled to 0.5uA after 2 minutes. Even after disconnecting for 1
minute the terminal voltage was around 60V+. The only thing I noticed was
capacitance had dropped from 2.30uF to 1.85uF (at 0 VDC bias) after the
test. However heating the capacitor with a soldering iron tip for a second
, had restored it to its original 2.30uF.

So what bad things are suppose to happen when you exceed the 10V spec. ?

I was making a EFL inverter, it had some 1nf 1205 400v caps in the filter,
when I was trying to get it to work ocassionaly the thing would resonate and
get so excited
sparks would jump acros the endcaps of the capacitors !

I was surprised the caps hadnt failed and gone short circuit, it was quite
spectacular.

Ive used some 10uf ceramic caps in a low leakage integrator application,
I measured the total leakage in the circuit and it was the same as the
leakage through the glass fiber pcb.
theres probably good reason why the guaranteed specs are seemingly somewhat
pessimistic.

Colin =^.^=

 

[Joerg]

I was wondering what happens when you put too much voltage across a one
of those low voltage multilayer ceramic capacitors. I took a 2.2uF 10V
X7R in 1206 package, and applied 95V across it and nothing exciting
happened. Leakage settled to 0.5uA after 2 minutes. Even after
disconnecting for 1 minute the terminal voltage was around 60V+. The
only thing I noticed was capacitance had dropped from 2.30uF to 1.85uF
(at 0 VDC bias) after the test. However heating the capacitor with a
soldering iron tip for a second , had restored it to its original 2.30uF.

So what bad things are suppose to happen when you exceed the 10V spec. ?

Be careful if that comes off a low impedance source. I have seen ceramic
turn into bubbly green glass with a loud bang.

 

[Ian]

I was wondering what happens when you put too much voltage across a one of
those low voltage multilayer ceramic capacitors. I took a 2.2uF 10V X7R in
1206 package, and applied 95V across it and nothing exciting happened.
Leakage settled to 0.5uA after 2 minutes. Even after disconnecting for 1
minute the terminal voltage was around 60V+. The only thing I noticed was
capacitance had dropped from 2.30uF to 1.85uF (at 0 VDC bias) after the
test. However heating the capacitor with a soldering iron tip for a second
, had restored it to its original 2.30uF.

So what bad things are suppose to happen when you exceed the 10V spec. ?

ISTR some information (AVX site?) saying that most ceramic caps will
survive several times the rated voltage, it is just that a few per batch may
not.

Regards
Ian

 

[Joerg]

ISTR some information (AVX site?) saying that most ceramic caps will
survive several times the rated voltage, it is just that a few per batch may
not.

Sounds like Russian roulette ;-)

 

[Adam S]

ISTR some information (AVX site?) saying that most ceramic caps will
survive several times the rated voltage, it is just that a few per batch may
not.

I only tested a couple of caps and didn't go higher that 95V on a 10V
rated device. Its interesting watching such a tiny thing make a nice
little blue spark when shorted.

 

[Tim Williams]

Hmmmmm. Methinks I want to buy a reel of a thousand, build an automatic
testing machine, and assemble the remaining ones (being made almost entirely
of magic smoke, the bad ones remove themselves from the machine with the
assistance of a small fan) into a rather large capacitor. Whaddya think,
energy density comparable to aluminum electrolytic at least? ;o) Power
density through the roof!

Tim

 

[Rich Grise]

On Mon, 02 Apr 2007 17:39:23 -0500, Tim Williams wrote:
[top-post repaired, see below]

Hmmmmm. Methinks I want to buy a reel of a thousand, build an automatic
testing machine, and assemble the remaining ones (being made almost entirely
of magic smoke, the bad ones remove themselves from the machine with the
assistance of a small fan) into a rather large capacitor. Whaddya think,
energy density comparable to aluminum electrolytic at least? ;o) Power
density through the roof!

If you've got the money, I've got the time! ;-)

Good Luck!
Rich

 

[Tim Williams]

If you've got the money, I've got the time! ;-)

College student :-(

Tim

 

[Rich Grise]

College student :-(

No, starving Contract Inventor. ;-)

Or, depending on how hungry I am at the moment, I can do grunt work.

Let's face it, who amongst us isn't a whore, some of us merely priced
higher than others? >:->

Thanks!
Rich

 

[whit3rd]

I was wondering what happens when you put too much voltage across a one
of those low voltage multilayer ceramic capacitors. I took a 2.2uF 10V
X7R in 1206 package, and applied 95V across it and nothing exciting
happened. Leakage settled to 0.5uA

I noticed was capacitance had dropped from 2.30uF to 1.85uF

The X7R and BK (and some other) capacitor ceramics are nonlinear
(actually ferroelectric), and the problem with overstress isn't
leakage or explosion. It's capacitance-value-droop. And as you
saw, the value stays out-of-spec after the stress is removed.
At 95V, if you'd measured it (put a known-good capacitor in series
and voltage-stress it then measure the series pair under voltage),
you might have found 0.2 uF.

A buddy of mine was trying to measure capacitors for a filter. He
never got the same value twice from the digi-bridge. I saw the
markings on the capacitor and laughed- it was the heat from his
fingers
as he handled the caps that made 'em always a few percent off
on successive measurements. Nonlinear materials are great for
energy density and in applications when you care little for AC
dissipation. They don't really obey the straight capacitance equation
very well, though.

 

[Tim Williams]

No, starving Contract Inventor. ;-)

Or, depending on how hungry I am at the moment, I can do grunt work.

Let's face it, who amongst us isn't a whore, some of us merely priced
higher than others? >:->

Churchill: Madam, would you sleep with me for five million pounds?
Socialite: My goodness, Mr. Churchill... Well, I suppose... we would have to
discuss terms, of course...
Churchill: Would you sleep with me for five pounds?
Socialite: Mr. Churchill, what kind of woman do you think I am?!
Churchill: Madam, we've already established that. Now we are haggling about
the price.
(From: wikiquote.org.)

Tim

 

[Rich Grise]

Churchill: Madam, would you sleep with me for five million pounds?
Socialite: My goodness, Mr. Churchill... Well, I suppose... we would have to
discuss terms, of course...
Churchill: Would you sleep with me for five pounds?
Socialite: Mr. Churchill, what kind of woman do you think I am?!
Churchill: Madam, we've already established that. Now we are haggling about
the price.
(From: wikiquote.org.)

That's an old Playboy Party Joke. The "real" Churchill quote, which
probably actually came from W.C.Fields, was:

Dowager: "Mr. Churchill, you are drunk!"
Churchy: "Madam, you are ugly. Tomorrow I shall be sober."

And then there's the one where a guy walks into a bar and sees a gal
with a duck under her arm:

Guy: "Hey, where did you get the pig?"
Gal: "That's an old joke!"
Guy: "I was talkin' to the joke."

Cheers!
Rich