Capacitors and ESD
blanko
Ceramtic?
Tantalum?
I know that some of the ceramic caps that I am working with are rated
at 25 volts. An ESD zap can be multiples of 1000 V. I believe that
the capacitors are ESD sensitive because I will exceed the max rated
voltage. Is this true?
Thank you.
-E
Tim Williams
What's a human body, about 1nF and 10kV worst case? Not going to do much to
anything over 0.1uF.
Tim
--
Deep Friar: a very philosophical monk.
Website: http://webpages.charter.net/dawill/tmoranwms
"blanko" <elect...@yahoo.com> wrote in message
news:a4aad671-1468-404f...@21g2000yqj.googlegroups.com...
John Larkin
<tmor...@charter.net> wrote:
>Capacitor divider. Run the numbers.
>
>What's a human body, about 1nF and 10kV worst case? Not going to do much to
>anything over 0.1uF.
>
>Tim
The common body model is 100 pF in series with 1.5K. That, charged to
10KV, dumps 10 volts into a 0.1 uF cap. Of course, it dumps most of
that 10KV into a 10 pF cap.
I tested some 0603 16 volt ceramic caps to see when they'd fail. At
120 volts, the limit of my supply, they were still OK.
John
whit3rd
> Are capacitors ESD sensitive? Please explain.
Yes, kinda, BUT if it's an electrolytic, it heals afterward, and if
it's a ceramic, there isn't any permanent damage, and it goes
back to 'normal' after a while (faster if it's hot).
Only the ultra-thin MOS capacitors of IC processes are really
likely to take permanent damage from a little bit of charge.
Some of the high-density ceramics are piezoelectric, and those
can turn nonlinear if you get 'em above the voltage rating. One
manufacturer actually required the capacitance value to be
measured BEFORE any verification of max sustainable voltage,
so the units wouldn't fail incoming testing.
Tim Williams
news:ot6al5pi072rjuve8...@4ax.com...
> I tested some 0603 16 volt ceramic caps to see when they'd fail. At
> 120 volts, the limit of my supply, they were still OK.
Of course, they'd be no good at bypassing at that voltage. The D-E curve
(think B-H) is going to be flat as Kansas.
John Larkin
<tmor...@charter.net> wrote:
>"John Larkin" <jjla...@highNOTlandTHIStechnologyPART.com> wrote in message
>news:ot6al5pi072rjuve8...@4ax.com...
>> I tested some 0603 16 volt ceramic caps to see when they'd fail. At
>> 120 volts, the limit of my supply, they were still OK.
>
>Of course, they'd be no good at bypassing at that voltage. The D-E curve
>(think B-H) is going to be flat as Kansas.
>
>Tim
Why are you spoiling my fun?
John
Tim Williams
>>Of course, they'd be no good at bypassing at that voltage. The D-E curve
>>(think B-H) is going to be flat as Kansas.
>
Fun? You aren't having fun, the damn thing didn't even explode. ;-)
John Larkin
<tmor...@charter.net> wrote:
>"John Larkin" <jjla...@highNOTlandTHIStechnologyPART.com> wrote in message
>news:6udal5t621q5fekd3...@4ax.com...
>>>Of course, they'd be no good at bypassing at that voltage. The D-E curve
>>>(think B-H) is going to be flat as Kansas.
>>
>> Why are you spoiling my fun?
>
>Fun? You aren't having fun, the damn thing didn't even explode. ;-)
>
>Tim
Ceramic caps are nonlinear enough that you could make a useful
parametric amplifier from some.
Hmmm, and a fA-sensitive amplifier.
John
Tim Williams
> Ceramic caps are nonlinear enough that you could make a useful
> parametric amplifier from some.
>
> Hmmm, and a fA-sensitive amplifier.
I recall HP already had made a leakage meter like that, using diode
capacitance instead.
With pA-sensitive op-amps available these days, there isn't much point in
doing that. Yeah, you said fA, but you'd be taking days to accumulate any
charge to measure it. Unless it was a microscopic hunk, like if you got at
a single cell of FeRAM. Ah, but a monolithic femtoammeter would perform
well, wouldn't it? Still, it would be quite noisy. You might end up with a
better thermometer.
Wimpie
Hello,
Yes ESD can destroy MLCC capacitors, even below the voltage breakdown
limit. Try to locate "DC, AC and Pulse Load
of Multilayer Ceramic Capacitors". This is a former PHILIPS document.
You can probably find it on www.koaspeer.com also. There are more
documents around, but this one gives the data in an easy to understand
way.
If you can't locate it, please contact me.
Best regards,
Wim
PA3DJS
www.tetech.nl
without abc your PM will reach me.
Wimpie
> On 19 ene, 00:39, blanko <electro...@yahoo.com> wrote:
>
> > Are capacitors ESD sensitive? Please explain.
>
> > Ceramtic?
>
> > Tantalum?
>
> > I know that some of the ceramic caps that I am working with are rated
> > at 25 volts. An ESD zap can be multiples of 1000 V. I believe that
> > the capacitors are ESD sensitive because I will exceed the max rated
> > voltage. Is this true?
>
> > Thank you.
>
> > -E
>
> Hello,
>
> Yes ESD can destroy MLCC capacitors, even below the voltage breakdown
> limit. Try to locate "DC, AC and Pulse Load
> of Multilayer Ceramic Capacitors". This is a former PHILIPS document.
> documents around, but this one gives the data in an easy to understand
> way.
>
> If you can't locate it, please contact me.
>
> Best regards,
>
> Wim
> PA3DJSwww.tetech.nl
> without abc your PM will reach me.
Addition to text shown above:
The link to the document is: http://www.koaspeer.com/pdfs/MLCC.pdf
Best regards,
Wim
PA3DJS
www.tetech.nl (Dutch)
blanko
I just sat down and read the document:
http://www.koaspeer.com/pdfs/MLCC.pdf
I was hoping that if ESD was a problem for capacitors that I would be
able to clearly understand that indeed there is an ESD issue. From
what I have read and digested - it seems that there is not an ESD
issue with capacitors.
Page 7 starts the section on ESD Pulses.
"The immunity of MLCCs to ESD pulses is not well characterized"
"When subjected to ESD pulses, low-capacitance MLCC's sometimes
exhibited corona effects without internal damage"
"All products were resistant to at least 2.5 kV HBM [Human Body Model]
and 1kV MM [Machine Model ]pules. 0805 and 1206 products showed the
same behaviour."
There are two graphs Fig. 12 and Fig. 14 that show the experimental
data on ESD immunity. I am not sure how to interpret these graphs.
Are the areas that are shaded problem areas?
Thanks for any clarification.
-H
Wimpie
> Wim,
>
> I just sat down and read the document:
>
> http://www.koaspeer.com/pdfs/MLCC.pdf
>
> I was hoping that if ESD was a problem for capacitors that I would be
> able to clearly understand that indeed there is an ESD issue. From
> what I have read and digested - it seems that there is not an ESD
> issue with capacitors.
Please locate the waveform for the EN 61000-4-2 ESD gun. For the 8 kV
pulse, the peak current is 30A. the I^2*t product is significantly
higher then the product for the human body model as used in the
document.
You should carry out I^2*t interpolation between the HBM, "your pulse"
and the PHILIPS MM to figure out whether the selected capacitors will
survive.
>
> Page 7 starts the section on ESD Pulses.
>
> "The immunity of MLCCs to ESD pulses is not well characterized"
Therefore they did this investigation.
>
> "When subjected to ESD pulses, low-capacitance MLCC's sometimes
> exhibited corona effects without internal damage"
>
> "All products were resistant to at least 2.5 kV HBM [Human Body Model]
> and 1kV MM [Machine Model ]pules. 0805 and 1206 products showed the
> same behaviour."
Depending on your environment, EN 61000-4-2 pulses can be up to 8 kV
(contact discharge).
>
> There are two graphs Fig. 12 and Fig. 14 that show the experimental
> data on ESD immunity. I am not sure how to interpret these graphs.
> Are the areas that are shaded problem areas?
Lower edge of shaded area: first capacitor fails, so below the shaded
area all survive
Higher edge of shaded area: all broken or damaged, so above the shaded
area all will be broken.
Because of the energy in the MM pulse, the pulse values in figure 14
are far below the voltages in figure 12.
[deleted]
JosephKK
>"John Larkin" <jjla...@highNOTlandTHIStechnologyPART.com> wrote in message
>news:fahal5h0g29cg6dbl...@4ax.com...
>> Ceramic caps are nonlinear enough that you could make a useful
>> parametric amplifier from some.
>>
>> Hmmm, and a fA-sensitive amplifier.
>
>I recall HP already had made a leakage meter like that, using diode
>capacitance instead.
>
>With pA-sensitive op-amps available these days, there isn't much point in
>doing that. Yeah, you said fA, but you'd be taking days to accumulate any
>charge to measure it. Unless it was a microscopic hunk, like if you got at
>a single cell of FeRAM. Ah, but a monolithic femtoammeter would perform
>well, wouldn't it? Still, it would be quite noisy. You might end up with a
>better thermometer.
>
>Tim
Comments like this make me appreciate Keithley 619 multimeters better.
John Larkin
Here's my ebay Keithley 610 measuring a surface-mount 100G resistor,
soldered to the Pomona plug. This meter's full-scale ranges go to
1e-14 amps and 1e14 ohms.
ftp://jjlarkin.lmi.net/Keithley.JPG
And here's my home-made fA parts tester...
ftp://jjlarkin.lmi.net/99A260A1.JPG
ftp://jjlarkin.lmi.net/99A260A3.JPG
ftp://jjlarkin.lmi.net/99S260A.JPG
Turns out that some cheap transistor c-b junctions are better pA
diodes than some official, expensive picoamp diodes.
I still want to demonstrate single-electron charge quantization at
room temp using available parts. It should be just possible.
John