have you ever seen silicon or teflon capacitors in anything?

[coppercone2]

They exist. They have descriptions.

Have you ever seen one inside of something? what was it?
https://www.electronicsweekly.com/news/products/teflon-high-film-capacitors-can-tolerate-150c-without-derating-2021-09/
https://eepower.com/technical-articles/beyond-mlccs-the-rise-of-the-silicon-capacitor/'

where are they hiding?

for the silicon cap, it looks like maybe the 1uF unit on mouser is the answer to the high value C0G capacitor.

[Gyro]

where are they hiding?

In dusty warehouses in the former Soviet Union ... https://www.ebay.co.uk/sch/i.html?_nkw=inkw=soviet+teflon+capacitor

[coppice]

Teflon capacitors, teflon coax, and lots of other things teflon are common in high end RF applications.

[themadhippy]

I had a teflon boss once,nothing would stick to him.

[coppice]

I had a teflon boss once,nothing would stick to him.

You haven't really seen a true one of those until you find one that has lost their employers at least a billion dollars. Loathed by everyone below them, and still being praised by those above.

[moffy]

We used teflon capacitors as the integrating capacitors for precision accelerometers for the Tornado fighter/bomber. They were large and cylindrical, tied to the board with glued wedges to hold them in place. The accelerometers had a variable magnetic force applied to their displacement lever to hold it at zero through a couple of coils. The current was integrated in the teflon cap and a precision charge pulse was applied to reset the cap, which was how the A/D conversion was done and the force was measured.
A story circulated around Ferranti about the Ariane rocket, for which we supplied the attitude measurement package. The French were the lead contractors and specified a supplier for these teflon caps for Ferranti. During environmental testing an inexplicable noise was found in the accelerometer loop, and it was traced to these teflon caps being vibration sensitive, acting as a microphone. Some fellows were dispatched to the supplier in Paris, who no one had heard of, and they found  a factory that consisted of someones garage! The solution was to change suppliers.

[coppercone2]

What is it not being wound tight enough?

the ones for sale now seem to be a mica/teflon hybrid.

[paul@yahrprobert.com]

As I recall, in one of Bob Pease's "Pease Porridge" columns he singled out teflon capacitors for having very low dielectric absorption, which is important for precision integrators.

[coppercone2]

how about silicon capacitors? lots of them in space right now? oil rigs?

[TimFox]

The usual app notes for sample/hold circuits recommended Teflon due to its low "soakage" (dielectric absorption), and they are also recommended for RF purposes due to low loss.
Besides the Soviet/Russian capacitors, and the audiophile units, there are manufacturers who make Teflon capacitors for high-temperature use.
https://www.electrocube.com/pages/433d-high-temperature-polytetrafluoroethylene-ptfe-teflon-foil-capacitors-data-sheet
https://www.electrocube.com/pages/463d-polytetrafluoroethylene-ptfe-teflon-metallized-high-temp-capacitor-data-sheet

[coppice]

how about silicon capacitors? lots of them in space right now? oil rigs?

Billions of them are embedded in ICs.

[coppice]

The usual app notes for sample/hold circuits recommended Teflon due to its low "soakage" (dielectric absorption), and they are also recommended for RF purposes due to low loss.
Besides the Soviet/Russian capacitors, and the audiophile units, there are manufacturers who make Teflon capacitors for high-temperature use.

Those are the key usage areas, although high temperature is misleading. Medium temperature might be more accurate. Teflon starts to emit toxic fumes at high temperature. It survives the normal usage of a frying pan, but that's about its limit. Teflon was banned from most airborne use because of this, although you'll still find small amounts in the RF equipment. Its great from day to day, but an over temperature incident could turn into a nightmare in a confined space.

[TimFox]

The usual app notes for sample/hold circuits recommended Teflon due to its low "soakage" (dielectric absorption), and they are also recommended for RF purposes due to low loss.
Besides the Soviet/Russian capacitors, and the audiophile units, there are manufacturers who make Teflon capacitors for high-temperature use.

Those are the key usage areas, although high temperature is misleading. Medium temperature might be more accurate. Teflon starts to emit toxic fumes at high temperature. It survives the normal usage of a frying pan, but that's about its limit. Teflon was banned from most airborne use because of this, although you'll still find small amounts in the RF equipment. Its great from day to day, but an over temperature incident could turn into a nightmare in a confined space.

Teflon disintegrates above 250^o C, which is higher than the other normal plastic films.  Polysulfone is about 190^o C.
Don't take these temperatures literally:  manufacturers of capacitors specify the actual temperature range.

[ejeffrey]

how about silicon capacitors? lots of them in space right now? oil rigs?

I've mostly seen them in wire bondable / die bondable form factors integrated into packages or on interposers for high speed bypassing.  Once you go out to a PCB they don't have much of an advantage over ceramic for bypassing.  They can be an alternative to COG for applications that need  stability and I have used them in cryogenic bypass applications where normal x5r types would loose too much capacitance.

[Terry Bites]

Me too, and I slung plenty his way. Some people huh?

[coppice]

The usual app notes for sample/hold circuits recommended Teflon due to its low "soakage" (dielectric absorption), and they are also recommended for RF purposes due to low loss.
Besides the Soviet/Russian capacitors, and the audiophile units, there are manufacturers who make Teflon capacitors for high-temperature use.

Those are the key usage areas, although high temperature is misleading. Medium temperature might be more accurate. Teflon starts to emit toxic fumes at high temperature. It survives the normal usage of a frying pan, but that's about its limit. Teflon was banned from most airborne use because of this, although you'll still find small amounts in the RF equipment. Its great from day to day, but an over temperature incident could turn into a nightmare in a confined space.

Teflon disintegrates above 250^o C, which is higher than the other normal plastic films.  Polysulfone is about 190^o C.
Don't take these temperatures literally:  manufacturers of capacitors specify the actual temperature range.

I think you missed the point. The key problem with telflon is the toxic fumes it generates when its hot, rather than not being able to tolerate the heat. The last time I worked on flight systems we used a lot of ETFE insulation. It takes pretty high temperatures, and decomposes in a less harmful way. Its a pain to work with, though, as it cracks quite easily.

[TimFox]

The usual app notes for sample/hold circuits recommended Teflon due to its low "soakage" (dielectric absorption), and they are also recommended for RF purposes due to low loss.
Besides the Soviet/Russian capacitors, and the audiophile units, there are manufacturers who make Teflon capacitors for high-temperature use.

Those are the key usage areas, although high temperature is misleading. Medium temperature might be more accurate. Teflon starts to emit toxic fumes at high temperature. It survives the normal usage of a frying pan, but that's about its limit. Teflon was banned from most airborne use because of this, although you'll still find small amounts in the RF equipment. Its great from day to day, but an over temperature incident could turn into a nightmare in a confined space.

Teflon disintegrates above 250^o C, which is higher than the other normal plastic films.  Polysulfone is about 190^o C.
Don't take these temperatures literally:  manufacturers of capacitors specify the actual temperature range.

I think you missed the point. The key problem with telflon is the toxic fumes it generates when its hot, rather than not being able to tolerate the heat. The last time I worked on flight systems we used a lot of ETFE insulation. It takes pretty high temperatures, and decomposes in a less harmful way. Its a pain to work with, though, as it cracks quite easily.

A NASA test document about Teflon capacitors, up to 200^o C:  https://ntrs.nasa.gov/api/citations/19920010798/downloads/19920010798.pdf
200^o C is quite high:  Silicon semiconductors fail at that temperature.
PVC insulation is worse:  depending on formulation, the max rated service temperature is only 90^o C.
Above that temperature, we are talking about extremely high temperatures.

[coppice]

A NASA test document about Teflon capacitors, up to 200^o C:  https://ntrs.nasa.gov/api/citations/19920010798/downloads/19920010798.pdf
200^o C is quite high:  Silicon semiconductors fail at that temperature.

We fry on teflon at 250C, but it doesn't take much more than that. Semiconductors don't fail at 200C. They have a reduced lifettime, and you can't afford to dissipate much at 200C or the die really will reach a temperature where it fails. There are a number of parts available rated for operation at 210C (not sure why they use that specific limit) or higher. They are expensive, and you tend to have to go to specialist catalogues to find them, but things like down hole oil well electronics demands these parts.

[PartialDischarge]

The 3458A has a teflon coaxial line capacitor as sample hold

[mqsaharan]

Fluke has been using variable Teflon capacitors rated for 2.0/1.7kV in their old handheld multimeters like 802XX, 806XA, 27, at the input for adjusting high frequency response at higher voltages.