NP0 / C0G long term stability

[John Devereux]

Hi,

Does anyone have any data on the likely long term stability (aging) of
C0G/NP0 chip capacitors? All I can find is that long term drift is
"zero"...

Thanks,

John

 

[John Devereux]

"C0G (NP0) is the most popular formulation of the "temperature-
compensating," EIA Class I ceramic materials. Modern
C0G (NP0) formulations contain neodymium, samarium and
other rare earth oxides.
C0G (NP0) ceramics offer one of the most stable capacitor
dielectrics available. Capacitance change with temperature
is 0 ±30ppm/°C which is less than ±0.3% Δ C from -55°C
to +125°C. Capacitance drift or hysteresis for C0G (NP0)
ceramics is negligible at less than ±0.05% versus up to
±2% for films. Typical capacitance change with life is less
than ±0.1% for C0G (NP0), one-fifth that shown by most
other dielectrics. C0G (NP0) formulations show no aging
characteristics.

Thanks, that is more than I found. I am still not sure if the actual
likely life stability is a lot less than that, or if that figure is just
a limitation of the measuring method.

The highest lifetime-stability surface mount parts I know of are the
Vishay metal foil resistors, at ~$10 each. These have a 100ppm lifetime
stability. I was wondering how a C0G capacitor would compare, since my
application could use either.

 

[John Devereux]

Manufacurers like AVX and Johanson flat out state no aging whatsoever
for this dielectric class. It's not the case for higher grade relative
permittivity types but it's a completely different technology of
dielectric so no extrapolation is possible.

But that extract you quoted was from an AVX datasheet wasn't it? That's
what came up anyway. Or is there some distinction between "aging" and
"capacitance change with life"?

Yes I am specifically talking about NP0/C0G rather than X7R etc.

 

[John Devereux]

Experimentally, the Susumu thinfilm resistors (more like 30 cents
each) drift less than 10 PPM per year, maybe much less. We make a
16-channel DAC board, where each channel uses an ADR421 and a dac and
5 Susumu's to define the output, and all the channels hold 10-15 PPM
per year.

Thanks, that is encouraging. The datasheets show up to 1000ppm for
various type of drifts though.

 

[John S]

Thanks, that is encouraging. The datasheets show up to 1000ppm for
various type of drifts though.

You may be looking at the wrong data sheets or data sheets from an
inferior manufacturer. Please provide a link to them.

 

[John Devereux]

[...]

Thanks, that is encouraging. The datasheets show up to 1000ppm for
various type of drifts though.

You may be looking at the wrong data sheets or data sheets from an
inferior manufacturer. Please provide a link to them.

I was looking at these:

<http://www.susumu-usa.com/pdf/RG_RM_RGH_DATASHEET.pdf>

 

[John S]

On Mon, 14 Nov 2011 15:34:44 +0000, John Devereux

[...]

Thanks, that is more than I found. I am still not sure if the actual
likely life stability is a lot less than that, or if that figure is just
a limitation of the measuring method.

The highest lifetime-stability surface mount parts I know of are the
Vishay metal foil resistors, at ~$10 each. These have a 100ppm lifetime
stability. I was wondering how a C0G capacitor would compare, since my
application could use either.

Experimentally, the Susumu thinfilm resistors (more like 30 cents
each) drift less than 10 PPM per year, maybe much less. We make a
16-channel DAC board, where each channel uses an ADR421 and a dac and
5 Susumu's to define the output, and all the channels hold 10-15 PPM
per year.

Thanks, that is encouraging. The datasheets show up to 1000ppm for
various type of drifts though.

You may be looking at the wrong data sheets or data sheets from an
inferior manufacturer. Please provide a link to them.

I was looking at these:

<http://www.susumu-usa.com/pdf/RG_RM_RGH_DATASHEET.pdf>

I apologize. I thought the thread was still on capacitors. My mistake.

 

[Jamie]

On 11/14/2011 1:50 PM, John Devereux wrote:


On Mon, 14 Nov 2011 15:34:44 +0000, John Devereux

[...]


Thanks, that is more than I found. I am still not sure if the actual
likely life stability is a lot less than that, or if that figure
is just
a limitation of the measuring method.

The highest lifetime-stability surface mount parts I know of are the
Vishay metal foil resistors, at ~$10 each. These have a 100ppm
lifetime
stability. I was wondering how a C0G capacitor would compare,
since my
application could use either.


Experimentally, the Susumu thinfilm resistors (more like 30 cents
each) drift less than 10 PPM per year, maybe much less. We make a
16-channel DAC board, where each channel uses an ADR421 and a dac and
5 Susumu's to define the output, and all the channels hold 10-15 PPM
per year.


Thanks, that is encouraging. The datasheets show up to 1000ppm for
various type of drifts though.



You may be looking at the wrong data sheets or data sheets from an
inferior manufacturer. Please provide a link to them.

I was looking at these:

<http://www.susumu-usa.com/pdf/RG_RM_RGH_DATASHEET.pdf>

I apologize. I thought the thread was still on capacitors. My mistake.

Well don't do that again!

Jamie

 

[John Devereux]

On 11/14/2011 1:50 PM, John Devereux wrote:

On Mon, 14 Nov 2011 15:34:44 +0000, John Devereux

[...]


Thanks, that is more than I found. I am still not sure if the actual
likely life stability is a lot less than that, or if that figure is just
a limitation of the measuring method.

The highest lifetime-stability surface mount parts I know of are the
Vishay metal foil resistors, at ~$10 each. These have a 100ppm lifetime
stability. I was wondering how a C0G capacitor would compare, since my
application could use either.

Experimentally, the Susumu thinfilm resistors (more like 30 cents
each) drift less than 10 PPM per year, maybe much less. We make a
16-channel DAC board, where each channel uses an ADR421 and a dac and
5 Susumu's to define the output, and all the channels hold 10-15 PPM
per year.

Thanks, that is encouraging. The datasheets show up to 1000ppm for
various type of drifts though.


You may be looking at the wrong data sheets or data sheets from an
inferior manufacturer. Please provide a link to them.

I was looking at these:

<http://www.susumu-usa.com/pdf/RG_RM_RGH_DATASHEET.pdf>

I apologize. I thought the thread was still on capacitors. My mistake.

Hey, no problem.

Really, I should probably use the susumus, 1000ppm is just about
acceptable and it seems that I likely will get much much better in
practice.

I just found it an intriguing possibility, with references to "zero",
"not measurable" drift of a 0.1 cent part, and having to spend $10 to
get a 100ppm resistor. That's 10000 times more expensive!

 

[Spehro Pefhany]

Well, ceramic materials are man-made rocks. There are surface
rocks that are as old as 4.5 billion years, so the 'aging' of a ceramic
capacitor will depend, in the long term, mainly on the metal/wire/coating
parts of the gizmo. Those are the same whether it's NP0 or any
other formulation.

Quite logical, perhaps sensible, but completely wrong.

http://www.johansondielectrics.com/...ral/capacitor-again/jdi_cap-aging_2006-03.pdf

Interesting that reflow soldering will "de-age" the capacitor, thus
maximizing the capacitance (and the drift) immediately after assembly!

So, if your design depends on, say, X7R capacitance, you can improve
stability over a typical product life considerably just by waiting a
few days after soldering before tuning it.


Best regards,
Spehro Pefhany

 

[John Devereux]

Quite logical, perhaps sensible, but completely wrong.

http://www.johansondielectrics.com/...ral/capacitor-again/jdi_cap-aging_2006-03.pdf

Interesting that reflow soldering will "de-age" the capacitor, thus
maximizing the capacitance (and the drift) immediately after assembly!

So, if your design depends on, say, X7R capacitance, you can improve
stability over a typical product life considerably just by waiting a
few days after soldering before tuning it.

That *is* interesting - unfortunately that reference does not help me
since it was NP0 I was interested it. Which they say "are stable over
time, temperature and voltage". Encouraging, but *how* stable?

 

[Spehro Pefhany]

Er... no, reread that article: it refers to spontaneous polarization of
ferroelectric materials, and those aren't part of any NP0 capacitor.
Ferroelectric materials are useful, but nonlinear, and they can polarize
for lots of reasons (not just age, but time-under-bias, I suspect).

You said " Those are the same whether it's NP0 or any other
formulation". X7R and Y5U are such.

That leaves open the possibility that the OP is worried about- that
there may be small residual aging effects.

A few years ago (okay, twelve!) John Woodgate mentioned that such
effects can be used to date when ancient pottery was fired.


Best regards,
Spehro Pefhany