film cap test...

[bitrex]

On 7/7/2022 1:07 PM, John Larkin wrote:

On Thu, 07 Jul 2022 07:51:24 -0700, jlarkin@highlandsniptechnology.com
wrote:

On Thu, 7 Jul 2022 10:39:39 -0400, Phil Hobbs
pcdhSpamMeSenseless@electrooptical.net> wrote:

Phil Allison wrote:
John Larkin wrote:
===============

The best one is this ugly brown radial-lead CDE thing.

https://www.dropbox.com/sh/d2mwz6i6yr0j9sp/AACJZ9IfJEGzdk0WGwsFb0MCa?dl=0

The 8 nH ESL number is shocking, hard to believe,

** Did you read the maker\'s spec?

No, I tested a few sample caps for another engineer, to check his
power supply Spice model and see if we\'ll have a problem with heating
from ripple current at 250 KHz. I\'m better equipped to measure these
things.

I like to measure (and explode) parts. I wonder what will happen if I
put kilovolts into this one. Any guesses?


Says <1nH per mm of body and lead length.

It\'s a bog standard, Ilinois Capacitor: MMR series, metallised polyester.

https://www.farnell.com/datasheets/2900812.pdf


The usual rule-of-thumb for wire is 20 nH per inch (800 pH/mm for the
imperially challenged). However, that cap is 26 mm long, not even
counting the banana connectors, which ought to be above 20 nH.

Cheers

Phil Hobbs

The conductive path, end to end, is probably many concentric cylinders
of foil, which I guess could have very low inductance. In my
measurement, the leads themselves seem to dominate L.

The frequency null computes to 8 nH against the 6.8 uF capacitance.
Things may not be that simple, but the tiny net impedance seems real.

I have a cool LCF program if anyone is interested.

I connected it to my trusty ole (it has one tube!) Kepco HV supply. I
was expecting a kilovolt at least, but at 250 volts it made popping
frying noises and got warm. But IR is still off the scale on my Fluke
DVM and it\'s still a capacitor around its original value.

https://www.dropbox.com/s/n1gp3h7h1v4bzw6/CDE_Guts.jpg?raw=1

It appears to be a metalized film spiral that has big metal (flame
sprayed?) electrodes on both ends.

We\'ll use lots of these so it\'s good to understand them.

Which tube is it? Using up those surplus TV shunt regulators?

 

[bitrex]

On 7/8/2022 4:30 PM, John Larkin wrote:

On Wed, 06 Jul 2022 14:34:59 -0700, John Larkin
jlarkin@highland_atwork_technology.com> wrote:


We want some biggish film caps to use in some LC filters for a couple
of switching power things, so we got some to test.

The best one is this ugly brown radial-lead CDE thing.

https://www.dropbox.com/sh/d2mwz6i6yr0j9sp/AACJZ9IfJEGzdk0WGwsFb0MCa?dl=0

The 8 nH ESL number is shocking, hard to believe, but if I scrooch it
into the test rig with longer leads the ESL spikes go way up,
consistent with the loop area, so the low ESL seems real. It will be
even lower soldered on a PCB, into some hunky copper planes.

Of course ESL is not a lumped property of a wound film cap, but this
is close.

We were considering some big ceramic caps, but they lose 80% of their
c at our 48 volts DC.

Here\'s a test of the c-v of a ceramic cap. We\'ll run at 60 volts as a
supply bypass, so we\'ll get about 1.2 uF, which will be OK if we put a
few in parallel with one big electro. That\'s smaller and less ESL than
a giant film cap.

https://www.dropbox.com/sh/7zlc8v29tgyoxrx/AABIyneKVEV-xX330TZTi4qTa?dl=0

We still need the big films in the supply output filter.

I could\'ve sworn I have some Xicon polystyrenes at 0.1uF in a box but
all I find currently available are 0.01 uF:

<https://www.mouser.com/c/passive-components/capacitors/film-capacitors/?dielectric=Polystyrene%20%28PS%29>

Have to remember to check what those big fatties are when I get home.
Maybe they made them bigger at one time.

 

[server]

On Sat, 9 Jul 2022 12:30:23 -0400, Phil Hobbs
<pcdhSpamMeSenseless@electrooptical.net> wrote:

jlarkin@highlandsniptechnology.com wrote:
On Fri, 8 Jul 2022 22:25:22 -0700 (PDT), whit3rd <whit3rd@gmail.com
wrote:

On Friday, July 8, 2022 at 5:01:07 PM UTC-7, bill....@ieee.org wrote:
On Saturday, July 9, 2022 at 8:23:23 AM UTC+10, ehsjr wrote:
On 7/7/2022 11:19 PM, Anthony William Sloman wrote:
On Friday, July 8, 2022 at 12:46:22 PM UTC+10, jla...@highlandsniptechnology.com wrote:
On Thu, 7 Jul 2022 18:27:24 -0400, Phil Hobbs <pcdhSpamM...@electrooptical.net> wrote:

Surface-mount film caps would have lower inductance, but I\'ve always
found them to be unreliable. They delaminate and wash water gets
between the layers.

So what\'s wrong with John Larkin\'s board-cleaning procedures?
Nothing. This is just another example of your anti-Larkin prejudice showing through. It\'s time someone pointed it out to you.

It was a perfectly sensible question. And it has got a perfectly sensible answer
The industry as a whole presumably finds them reliable enough.
As legg pointed out
No they don\'t. They wish they could, but not so far.

SMT parts are stacked film, without any environmental seal on the sheared edges.
They need to be sealed to survive, so conformal coatings encapsulation of the final assy is required.

So it wasn\'t John Larkin\'s board cleaning procedures that were inadequate, but rather his failure to apply a conformal coating to what he clearly now knows to be a vulnerable part.

That seems odd; you don\'t want to conformal coat before soldering, and you don\'t want to
solder, then conformal coat before washing, do you?

I suppose you could install wire-wrap posts, clean the board, but conformal coat (the capacitors), then
rely on wire-wrap attachment of the capacitors to insulation-displace the coating...
otherwise, the conformal coating that matters has to be selectively applied
before putting the parts into a reel.

Sounds labor intensive.

One hopes
the capacitor manufacture process has been designed with this issue in mind.

Just use radial leaded film caps.

When I wanted to see the innards of my brown 6.8u film cap. I put it
on an anvil and hit it with a hammer. Nothing happened. The way to get
inside was to put it in a big vise, lengthwise, and squeeze it until
the shell shattered.


Yeah, through-hole film caps rock. They\'re really the only technology
for applications needing good linearity at higher CV values than you can
get in C0G. One typical use for us is filtering the bias supplies for
avalanche photodiodes and SiPMs, but they\'re also good for slow analog
ramps.

Cheers

Phil Hobbs

What\'s best these days for low D.A?

 

[server]

On Sat, 9 Jul 2022 12:46:48 -0400, bitrex <user@example.net> wrote:

On 7/8/2022 4:30 PM, John Larkin wrote:
On Wed, 06 Jul 2022 14:34:59 -0700, John Larkin
jlarkin@highland_atwork_technology.com> wrote:


We want some biggish film caps to use in some LC filters for a couple
of switching power things, so we got some to test.

The best one is this ugly brown radial-lead CDE thing.

https://www.dropbox.com/sh/d2mwz6i6yr0j9sp/AACJZ9IfJEGzdk0WGwsFb0MCa?dl=0

The 8 nH ESL number is shocking, hard to believe, but if I scrooch it
into the test rig with longer leads the ESL spikes go way up,
consistent with the loop area, so the low ESL seems real. It will be
even lower soldered on a PCB, into some hunky copper planes.

Of course ESL is not a lumped property of a wound film cap, but this
is close.

We were considering some big ceramic caps, but they lose 80% of their
c at our 48 volts DC.

Here\'s a test of the c-v of a ceramic cap. We\'ll run at 60 volts as a
supply bypass, so we\'ll get about 1.2 uF, which will be OK if we put a
few in parallel with one big electro. That\'s smaller and less ESL than
a giant film cap.

https://www.dropbox.com/sh/7zlc8v29tgyoxrx/AABIyneKVEV-xX330TZTi4qTa?dl=0

We still need the big films in the supply output filter.



I could\'ve sworn I have some Xicon polystyrenes at 0.1uF in a box but
all I find currently available are 0.01 uF:

https://www.mouser.com/c/passive-components/capacitors/film-capacitors/?dielectric=Polystyrene%20%28PS%29

Have to remember to check what those big fatties are when I get home.
Maybe they made them bigger at one time.

Those are great but chemically/physically/thermally fragile.
Accidentally touch one with a soldering iron and they die.

 

[Phil Hobbs]

jlarkin@highlandsniptechnology.com wrote:

On Sat, 9 Jul 2022 12:30:23 -0400, Phil Hobbs
pcdhSpamMeSenseless@electrooptical.net> wrote:

jlarkin@highlandsniptechnology.com wrote:
On Fri, 8 Jul 2022 22:25:22 -0700 (PDT), whit3rd <whit3rd@gmail.com
wrote:

On Friday, July 8, 2022 at 5:01:07 PM UTC-7, bill....@ieee.org wrote:
On Saturday, July 9, 2022 at 8:23:23 AM UTC+10, ehsjr wrote:
On 7/7/2022 11:19 PM, Anthony William Sloman wrote:
On Friday, July 8, 2022 at 12:46:22 PM UTC+10, jla...@highlandsniptechnology.com wrote:
On Thu, 7 Jul 2022 18:27:24 -0400, Phil Hobbs <pcdhSpamM...@electrooptical.net> wrote:

Surface-mount film caps would have lower inductance, but I\'ve always
found them to be unreliable. They delaminate and wash water gets
between the layers.

So what\'s wrong with John Larkin\'s board-cleaning procedures?
Nothing. This is just another example of your anti-Larkin prejudice showing through. It\'s time someone pointed it out to you.

It was a perfectly sensible question. And it has got a perfectly sensible answer
The industry as a whole presumably finds them reliable enough.
As legg pointed out
No they don\'t. They wish they could, but not so far.

SMT parts are stacked film, without any environmental seal on the sheared edges.
They need to be sealed to survive, so conformal coatings encapsulation of the final assy is required.

So it wasn\'t John Larkin\'s board cleaning procedures that were inadequate, but rather his failure to apply a conformal coating to what he clearly now knows to be a vulnerable part.

That seems odd; you don\'t want to conformal coat before soldering, and you don\'t want to
solder, then conformal coat before washing, do you?

I suppose you could install wire-wrap posts, clean the board, but conformal coat (the capacitors), then
rely on wire-wrap attachment of the capacitors to insulation-displace the coating...
otherwise, the conformal coating that matters has to be selectively applied
before putting the parts into a reel.

Sounds labor intensive.

One hopes
the capacitor manufacture process has been designed with this issue in mind.

Just use radial leaded film caps.

When I wanted to see the innards of my brown 6.8u film cap. I put it
on an anvil and hit it with a hammer. Nothing happened. The way to get
inside was to put it in a big vise, lengthwise, and squeeze it until
the shell shattered.


Yeah, through-hole film caps rock. They\'re really the only technology
for applications needing good linearity at higher CV values than you can
get in C0G. One typical use for us is filtering the bias supplies for
avalanche photodiodes and SiPMs, but they\'re also good for slow analog
ramps.

Cheers

Phil Hobbs

What\'s best these days for low D.A?

Seems like all the work on film caps centers on high temperatures, for
obvious reasons--the old faithful mylar (polyester), polypropylene, and
(especially) polystyrene dielectrics won\'t stand SMT reflow. The best
of the newer materials is polyphenylene sulfide (PPS). The newer,
cheaper alternative is polyethylene naphthalate (PEN), but it has, like,
2 orders of magnitude worse soakage than PPS.

Polystyrene melts at around 100C, but is otherwise about the best
dielectric out there--super low soakage, super low leakage, excellent
linearity. Unfortunately it isn\'t out there much anymore.

The only outfit I know of that sells them these days is Xicon, and I\'ve
never used theirs. I should try them out--BITD polystyrene caps mostly
came in

Teflon is also super good, but is a bit of a cottage industry at this
point--there are tales told about the inability of suppliers (of the
teflon film stock) to maintain quality.

Polyester is pretty good except for its weird cubic tempco curve.

So for the most part I use polypropylene.

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC / Hobbs ElectroOptics
Optics, Electro-optics, Photonics, Analog Electronics
Briarcliff Manor NY 10510

http://electrooptical.net
http://hobbs-eo.com

 

[Phil Hobbs]

Phil Hobbs wrote:

jlarkin@highlandsniptechnology.com wrote:
On Sat, 9 Jul 2022 12:30:23 -0400, Phil Hobbs
pcdhSpamMeSenseless@electrooptical.net> wrote:

jlarkin@highlandsniptechnology.com wrote:
On Fri, 8 Jul 2022 22:25:22 -0700 (PDT), whit3rd <whit3rd@gmail.com
wrote:

On Friday, July 8, 2022 at 5:01:07 PM UTC-7, bill....@ieee.org wrote:
On Saturday, July 9, 2022 at 8:23:23 AM UTC+10, ehsjr wrote:
On 7/7/2022 11:19 PM, Anthony William Sloman wrote:
On Friday, July 8, 2022 at 12:46:22 PM UTC+10,
jla...@highlandsniptechnology.com wrote:
On Thu, 7 Jul 2022 18:27:24 -0400, Phil Hobbs
pcdhSpamM...@electrooptical.net> wrote:

Surface-mount film caps would have lower inductance, but I\'ve
always
found them to be unreliable. They delaminate and wash water gets
between the layers.

So what\'s wrong with John Larkin\'s board-cleaning procedures?
Nothing. This is just another example of your anti-Larkin
prejudice showing through. It\'s time someone pointed it out to you.

It was a perfectly sensible question. And it has got a perfectly
sensible answer
The industry as a whole presumably finds them reliable enough.
As legg pointed out
No they don\'t. They wish they could, but not so far.

SMT parts are stacked film, without any environmental seal on the
sheared edges.
They need to be sealed to survive, so conformal coatings
encapsulation of the final assy is required.

So it wasn\'t John Larkin\'s board cleaning procedures that were
inadequate, but rather his failure to apply a conformal coating to
what he clearly now knows to be a vulnerable part.

That seems odd; you don\'t want to conformal coat before soldering,
and you don\'t want to
solder, then conformal coat before washing, do you?

I suppose you could install wire-wrap posts, clean the board, but
conformal coat (the capacitors), then
rely on wire-wrap attachment of the capacitors to
insulation-displace the coating...
otherwise, the conformal coating that matters has to be selectively
applied
before putting the parts into a reel.

Sounds labor intensive.

    One hopes
the capacitor manufacture process has been designed with this issue
in mind.

Just use radial leaded film caps.

When I wanted to see the innards of my brown 6.8u film cap. I put it
on an anvil and hit it with a hammer. Nothing happened. The way to get
inside was to put it in a big vise, lengthwise, and squeeze it until
the shell shattered.


Yeah, through-hole film caps rock. They\'re really the only technology
for applications needing good linearity at higher CV values than you can
get in C0G.  One typical use for us is filtering the bias supplies for
avalanche photodiodes and SiPMs, but they\'re also good for slow analog
ramps.

Cheers

Phil Hobbs

What\'s best these days for low D.A?


Seems like all the work on film caps centers on high temperatures, for
obvious reasons--the old faithful mylar (polyester), polypropylene, and
(especially) polystyrene dielectrics won\'t stand SMT reflow.  The best
of the newer materials is polyphenylene sulfide (PPS).  The newer,
cheaper alternative is polyethylene naphthalate (PEN), but it has, like,
2 orders of magnitude worse soakage than PPS.

Polystyrene melts at around 100C, but is otherwise about the best
dielectric out there--super low soakage, super low leakage, excellent
linearity.  Unfortunately it isn\'t out there much anymore.

The only outfit I know of that sells them these days is Xicon, and I\'ve
never used theirs.  I should try them out--BITD polystyrene caps mostly
came in

1% tolerances at very high prices, but these 5% ones look like they
might be OK, and they\'re sure cheaper.

Teflon is also super good, but is a bit of a cottage industry at this
point--there are tales told about the inability of suppliers (of the
teflon film stock) to maintain quality.

Polyester is pretty good except for its weird cubic tempco curve.

So for the most part I use polypropylene.

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC / Hobbs ElectroOptics
Optics, Electro-optics, Photonics, Analog Electronics
Briarcliff Manor NY 10510

http://electrooptical.net
http://hobbs-eo.com

 

[Phil Hobbs]

jlarkin@highlandsniptechnology.com wrote:

On Sat, 9 Jul 2022 12:46:48 -0400, bitrex <user@example.net> wrote:

On 7/8/2022 4:30 PM, John Larkin wrote:
On Wed, 06 Jul 2022 14:34:59 -0700, John Larkin
jlarkin@highland_atwork_technology.com> wrote:
snip

We still need the big films in the supply output filter.



I could\'ve sworn I have some Xicon polystyrenes at 0.1uF in a box but
all I find currently available are 0.01 uF:

https://www.mouser.com/c/passive-components/capacitors/film-capacitors/?dielectric=Polystyrene%20%28PS%29

Have to remember to check what those big fatties are when I get home.
Maybe they made them bigger at one time.

Those are great but chemically/physically/thermally fragile.
Accidentally touch one with a soldering iron and they die.

\"Doctor, Doctor, it hurts when I go like this!\"

\"So don\'t go like that.\"

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC / Hobbs ElectroOptics
Optics, Electro-optics, Photonics, Analog Electronics
Briarcliff Manor NY 10510

http://electrooptical.net
http://hobbs-eo.com

 

[server]

On Sat, 9 Jul 2022 17:49:22 -0400, Phil Hobbs
<pcdhSpamMeSenseless@electrooptical.net> wrote:

jlarkin@highlandsniptechnology.com wrote:
On Sat, 9 Jul 2022 12:46:48 -0400, bitrex <user@example.net> wrote:

On 7/8/2022 4:30 PM, John Larkin wrote:
On Wed, 06 Jul 2022 14:34:59 -0700, John Larkin
jlarkin@highland_atwork_technology.com> wrote:
snip

We still need the big films in the supply output filter.



I could\'ve sworn I have some Xicon polystyrenes at 0.1uF in a box but
all I find currently available are 0.01 uF:

https://www.mouser.com/c/passive-components/capacitors/film-capacitors/?dielectric=Polystyrene%20%28PS%29

Have to remember to check what those big fatties are when I get home.
Maybe they made them bigger at one time.

Those are great but chemically/physically/thermally fragile.
Accidentally touch one with a soldering iron and they die.

\"Doctor, Doctor, it hurts when I go like this!\"

\"So don\'t go like that.\"

Cheers

Phil Hobbs

Doctor, Doctor, it hurts when I breathe!


Actually, the best non-vacuum caps are SiO2 layers in ICs. That\'s why
they are used in SAR ADCs.

 

[bitrex]

On 7/9/2022 5:49 PM, Phil Hobbs wrote:

jlarkin@highlandsniptechnology.com wrote:
On Sat, 9 Jul 2022 12:46:48 -0400, bitrex <user@example.net> wrote:

On 7/8/2022 4:30 PM, John Larkin wrote:
On Wed, 06 Jul 2022 14:34:59 -0700, John Larkin
jlarkin@highland_atwork_technology.com> wrote:
snip

We still need the big films in the supply output filter.



I could\'ve sworn I have some Xicon polystyrenes at 0.1uF in a box but
all I find currently available are 0.01 uF:

https://www.mouser.com/c/passive-components/capacitors/film-capacitors/?dielectric=Polystyrene%20%28PS%29


Have to remember to check what those big fatties are when I get home.
Maybe they made them bigger at one time.

Those are great but chemically/physically/thermally fragile.
Accidentally touch one with a soldering iron and they die.

\"Doctor, Doctor, it hurts when I go like this!\"

\"So don\'t go like that.\"

Cheers

Phil Hobbs

They do tend to give you about 3\" worth of lead on each end of the axial
polystyrenes. I\'ve never used them above a few 100s of kHz as it\'s my
understanding they\'re kinda lousy in the MHz range even without the lead
inductance. But down lower in e.g. integrator they\'re basically ideal caps

 

[bitrex]

On 7/9/2022 6:38 PM, jlarkin@highlandsniptechnology.com wrote:

On Sat, 9 Jul 2022 17:49:22 -0400, Phil Hobbs
pcdhSpamMeSenseless@electrooptical.net> wrote:

jlarkin@highlandsniptechnology.com wrote:
On Sat, 9 Jul 2022 12:46:48 -0400, bitrex <user@example.net> wrote:

On 7/8/2022 4:30 PM, John Larkin wrote:
On Wed, 06 Jul 2022 14:34:59 -0700, John Larkin
jlarkin@highland_atwork_technology.com> wrote:
snip

We still need the big films in the supply output filter.



I could\'ve sworn I have some Xicon polystyrenes at 0.1uF in a box but
all I find currently available are 0.01 uF:

https://www.mouser.com/c/passive-components/capacitors/film-capacitors/?dielectric=Polystyrene%20%28PS%29

Have to remember to check what those big fatties are when I get home.
Maybe they made them bigger at one time.

Those are great but chemically/physically/thermally fragile.
Accidentally touch one with a soldering iron and they die.

\"Doctor, Doctor, it hurts when I go like this!\"

\"So don\'t go like that.\"

Cheers

Phil Hobbs

Doctor, Doctor, it hurts when I breathe!


Actually, the best non-vacuum caps are SiO2 layers in ICs. That\'s why
they are used in SAR ADCs.

Big fatties!

<https://www.ebay.com/itm/194980431793>

A little smaller than a sewing thimble, IIRC. I think the fattest
non-electro caps I have in my bin are some 1uF 1000 volt metalized
polypropylene, those are getting into
could-injure-someone-if-you-threw-it-at-them size.

 

[Carl]

On 7/9/22 15:14, Phil Hobbs wrote:

Phil Hobbs wrote:
jlarkin@highlandsniptechnology.com wrote:
On Sat, 9 Jul 2022 12:30:23 -0400, Phil Hobbs
pcdhSpamMeSenseless@electrooptical.net> wrote:

jlarkin@highlandsniptechnology.com wrote:
On Fri, 8 Jul 2022 22:25:22 -0700 (PDT), whit3rd <whit3rd@gmail.com
wrote:

On Friday, July 8, 2022 at 5:01:07 PM UTC-7, bill....@ieee.org wrote:
On Saturday, July 9, 2022 at 8:23:23 AM UTC+10, ehsjr wrote:
On 7/7/2022 11:19 PM, Anthony William Sloman wrote:
On Friday, July 8, 2022 at 12:46:22 PM UTC+10,
jla...@highlandsniptechnology.com wrote:
On Thu, 7 Jul 2022 18:27:24 -0400, Phil Hobbs
pcdhSpamM...@electrooptical.net> wrote:

Surface-mount film caps would have lower inductance, but I\'ve
always
found them to be unreliable. They delaminate and wash water gets
between the layers.

So what\'s wrong with John Larkin\'s board-cleaning procedures?
Nothing. This is just another example of your anti-Larkin
prejudice showing through. It\'s time someone pointed it out to you.

It was a perfectly sensible question. And it has got a perfectly
sensible answer
The industry as a whole presumably finds them reliable enough.
As legg pointed out
No they don\'t. They wish they could, but not so far.

SMT parts are stacked film, without any environmental seal on
the sheared edges.
They need to be sealed to survive, so conformal coatings
encapsulation of the final assy is required.

So it wasn\'t John Larkin\'s board cleaning procedures that were
inadequate, but rather his failure to apply a conformal coating
to what he clearly now knows to be a vulnerable part.

That seems odd; you don\'t want to conformal coat before soldering,
and you don\'t want to
solder, then conformal coat before washing, do you?

I suppose you could install wire-wrap posts, clean the board, but
conformal coat (the capacitors), then
rely on wire-wrap attachment of the capacitors to
insulation-displace the coating...
otherwise, the conformal coating that matters has to be
selectively applied
before putting the parts into a reel.

Sounds labor intensive.

    One hopes
the capacitor manufacture process has been designed with this
issue in mind.

Just use radial leaded film caps.

When I wanted to see the innards of my brown 6.8u film cap. I put it
on an anvil and hit it with a hammer. Nothing happened. The way to get
inside was to put it in a big vise, lengthwise, and squeeze it until
the shell shattered.


Yeah, through-hole film caps rock. They\'re really the only technology
for applications needing good linearity at higher CV values than you
can
get in C0G.  One typical use for us is filtering the bias supplies for
avalanche photodiodes and SiPMs, but they\'re also good for slow analog
ramps.

Cheers

Phil Hobbs

What\'s best these days for low D.A?


Seems like all the work on film caps centers on high temperatures, for
obvious reasons--the old faithful mylar (polyester), polypropylene,
and (especially) polystyrene dielectrics won\'t stand SMT reflow.  The
best of the newer materials is polyphenylene sulfide (PPS).  The
newer, cheaper alternative is polyethylene naphthalate (PEN), but it
has, like, 2 orders of magnitude worse soakage than PPS.

Polystyrene melts at around 100C, but is otherwise about the best
dielectric out there--super low soakage, super low leakage, excellent
linearity.  Unfortunately it isn\'t out there much anymore.

The only outfit I know of that sells them these days is Xicon, and
I\'ve never used theirs.  I should try them out--BITD polystyrene caps
mostly came in

1% tolerances at very high prices, but these 5% ones look like they
might be OK, and they\'re sure cheaper.


Teflon is also super good, but is a bit of a cottage industry at this
point--there are tales told about the inability of suppliers (of the
teflon film stock) to maintain quality.

Polyester is pretty good except for its weird cubic tempco curve.

So for the most part I use polypropylene.

Cheers

Phil Hobbs

How about PEEK? I did some quick googling and found thin film suppliers
but no capacitors. Should be good mechanically and thermally but I
don\'t know about the things that matter for a capacitor like dielectric
constant, D. A., thermal coefficients, etc. PI (Kynar) might also be
good, and Wikipedia actually said someone claimed to offer one but no
details were available. If anyone wants to try making some I did find
one place selling a pack of 15 different films for capacitor R&D that
includes PEEK and PI, for a mere $2000 .
https://piezopvdf.com/15-type-polymer-capacitor-film-kit/

--
Regards,
Carl

 

[Phil Hobbs]

Carl wrote:

On 7/9/22 15:14, Phil Hobbs wrote:
Phil Hobbs wrote:
jlarkin@highlandsniptechnology.com wrote:
On Sat, 9 Jul 2022 12:30:23 -0400, Phil Hobbs
pcdhSpamMeSenseless@electrooptical.net> wrote:

jlarkin@highlandsniptechnology.com wrote:
On Fri, 8 Jul 2022 22:25:22 -0700 (PDT), whit3rd <whit3rd@gmail.com
wrote:

On Friday, July 8, 2022 at 5:01:07 PM UTC-7, bill....@ieee.org
wrote:
On Saturday, July 9, 2022 at 8:23:23 AM UTC+10, ehsjr wrote:
On 7/7/2022 11:19 PM, Anthony William Sloman wrote:
On Friday, July 8, 2022 at 12:46:22 PM UTC+10,
jla...@highlandsniptechnology.com wrote:
On Thu, 7 Jul 2022 18:27:24 -0400, Phil Hobbs
pcdhSpamM...@electrooptical.net> wrote:

Surface-mount film caps would have lower inductance, but I\'ve
always
found them to be unreliable. They delaminate and wash water gets
between the layers.

So what\'s wrong with John Larkin\'s board-cleaning procedures?
Nothing. This is just another example of your anti-Larkin
prejudice showing through. It\'s time someone pointed it out to
you.

It was a perfectly sensible question. And it has got a perfectly
sensible answer
The industry as a whole presumably finds them reliable enough.
As legg pointed out
No they don\'t. They wish they could, but not so far.

SMT parts are stacked film, without any environmental seal on
the sheared edges.
They need to be sealed to survive, so conformal coatings
encapsulation of the final assy is required.

So it wasn\'t John Larkin\'s board cleaning procedures that were
inadequate, but rather his failure to apply a conformal coating
to what he clearly now knows to be a vulnerable part.

That seems odd; you don\'t want to conformal coat before
soldering, and you don\'t want to
solder, then conformal coat before washing, do you?

I suppose you could install wire-wrap posts, clean the board, but
conformal coat (the capacitors), then
rely on wire-wrap attachment of the capacitors to
insulation-displace the coating...
otherwise, the conformal coating that matters has to be
selectively applied
before putting the parts into a reel.

Sounds labor intensive.

    One hopes
the capacitor manufacture process has been designed with this
issue in mind.

Just use radial leaded film caps.

When I wanted to see the innards of my brown 6.8u film cap. I put it
on an anvil and hit it with a hammer. Nothing happened. The way to
get
inside was to put it in a big vise, lengthwise, and squeeze it until
the shell shattered.


Yeah, through-hole film caps rock. They\'re really the only technology
for applications needing good linearity at higher CV values than
you can
get in C0G.  One typical use for us is filtering the bias supplies for
avalanche photodiodes and SiPMs, but they\'re also good for slow analog
ramps.

Cheers

Phil Hobbs

What\'s best these days for low D.A?


Seems like all the work on film caps centers on high temperatures,
for obvious reasons--the old faithful mylar (polyester),
polypropylene, and (especially) polystyrene dielectrics won\'t stand
SMT reflow.  The best of the newer materials is polyphenylene sulfide
(PPS).  The newer, cheaper alternative is polyethylene naphthalate
(PEN), but it has, like, 2 orders of magnitude worse soakage than PPS.

Polystyrene melts at around 100C, but is otherwise about the best
dielectric out there--super low soakage, super low leakage, excellent
linearity.  Unfortunately it isn\'t out there much anymore.

The only outfit I know of that sells them these days is Xicon, and
I\'ve never used theirs.  I should try them out--BITD polystyrene caps
mostly came in

1% tolerances at very high prices, but these 5% ones look like they
might be OK, and they\'re sure cheaper.


Teflon is also super good, but is a bit of a cottage industry at this
point--there are tales told about the inability of suppliers (of the
teflon film stock) to maintain quality.

Polyester is pretty good except for its weird cubic tempco curve.

So for the most part I use polypropylene.

Cheers

Phil Hobbs

How about PEEK?  I did some quick googling and found thin film suppliers
but no capacitors.  Should be good mechanically and thermally but I
don\'t know about the things that matter for a capacitor like dielectric
constant, D. A., thermal coefficients, etc.  PI (Kynar) might also be
good, and Wikipedia actually said someone claimed to offer one but no
details were available.  If anyone wants to try making some I did find
one place selling a pack of 15 different films for capacitor R&D that
includes PEEK and PI, for a mere $2000 .
https://piezopvdf.com/15-type-polymer-capacitor-film-kit/

Dunno. There are a lot of things that you\'d expect to make good
dielectrics that don\'t. Glass caps, for instance, have soakage that has
to be seen to be believed.

Cheers

Phil Hobbs
--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC / Hobbs ElectroOptics
Optics, Electro-optics, Photonics, Analog Electronics
Briarcliff Manor NY 10510

http://electrooptical.net
http://hobbs-eo.com

 

[Phil Hobbs]

jlarkin@highlandsniptechnology.com wrote:

On Sat, 9 Jul 2022 17:49:22 -0400, Phil Hobbs
pcdhSpamMeSenseless@electrooptical.net> wrote:

jlarkin@highlandsniptechnology.com wrote:
On Sat, 9 Jul 2022 12:46:48 -0400, bitrex <user@example.net> wrote:

On 7/8/2022 4:30 PM, John Larkin wrote:
On Wed, 06 Jul 2022 14:34:59 -0700, John Larkin
jlarkin@highland_atwork_technology.com> wrote:
snip

We still need the big films in the supply output filter.



I could\'ve sworn I have some Xicon polystyrenes at 0.1uF in a box but
all I find currently available are 0.01 uF:

https://www.mouser.com/c/passive-components/capacitors/film-capacitors/?dielectric=Polystyrene%20%28PS%29

Have to remember to check what those big fatties are when I get home.
Maybe they made them bigger at one time.

Those are great but chemically/physically/thermally fragile.
Accidentally touch one with a soldering iron and they die.

\"Doctor, Doctor, it hurts when I go like this!\"

\"So don\'t go like that.\"

Cheers

Phil Hobbs

Doctor, Doctor, it hurts when I breathe!


Actually, the best non-vacuum caps are SiO2 layers in ICs. That\'s why
they are used in SAR ADCs.

Well, the lack of available alternatives has something to do with that
too.

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC / Hobbs ElectroOptics
Optics, Electro-optics, Photonics, Analog Electronics
Briarcliff Manor NY 10510

http://electrooptical.net
http://hobbs-eo.com

 

[Anthony William Sloman]

On Sunday, July 10, 2022 at 2:30:36 AM UTC+10, Phil Hobbs wrote:

jla...@highlandsniptechnology.com wrote:
On Fri, 8 Jul 2022 22:25:22 -0700 (PDT), whit3rd <whi...@gmail.com
wrote:

On Friday, July 8, 2022 at 5:01:07 PM UTC-7, bill....@ieee.org wrote:
On Saturday, July 9, 2022 at 8:23:23 AM UTC+10, ehsjr wrote:
On 7/7/2022 11:19 PM, Anthony William Sloman wrote:
On Friday, July 8, 2022 at 12:46:22 PM UTC+10, jla...@highlandsniptechnology.com wrote:
On Thu, 7 Jul 2022 18:27:24 -0400, Phil Hobbs <pcdhSpamM...@electrooptical.net> wrote:

Surface-mount film caps would have lower inductance, but I\'ve always
found them to be unreliable. They delaminate and wash water gets
between the layers.

So what\'s wrong with John Larkin\'s board-cleaning procedures?
Nothing. This is just another example of your anti-Larkin prejudice showing through. It\'s time someone pointed it out to you.

It was a perfectly sensible question. And it has got a perfectly sensible answer
The industry as a whole presumably finds them reliable enough.
As legg pointed out
No they don\'t. They wish they could, but not so far.

SMT parts are stacked film, without any environmental seal on the sheared edges.
They need to be sealed to survive, so conformal coatings encapsulation of the final assy is required.

So it wasn\'t John Larkin\'s board cleaning procedures that were inadequate, but rather his failure to apply a conformal coating to what he clearly now knows to be a vulnerable part.

That seems odd; you don\'t want to conformal coat before soldering, and you don\'t want to
solder, then conformal coat before washing, do you?

I suppose you could install wire-wrap posts, clean the board, but conformal coat (the capacitors), then
rely on wire-wrap attachment of the capacitors to insulation-displace the coating...
otherwise, the conformal coating that matters has to be selectively applied
before putting the parts into a reel.

Sounds labor intensive.

One hopes
the capacitor manufacture process has been designed with this issue in mind.

Just use radial leaded film caps.

When I wanted to see the innards of my brown 6.8u film cap. I put it
on an anvil and hit it with a hammer. Nothing happened. The way to get
inside was to put it in a big vise, lengthwise, and squeeze it until
the shell shattered.

Yeah, through-hole film caps rock. They\'re really the only technology
for applications needing good linearity at higher CV values than you can
get in C0G. One typical use for us is filtering the bias supplies for
avalanche photodiodes and SiPMs, but they\'re also good for slow analog
ramps.

You\'ve got to pick your dielectric film carefully if you want a linear analog ramp. Charge soak can be a problem for polyester films, and polycarbonate films aren\'t all that much better. Polypropylene films are quite a bit better, and teflon films are supposed to be even better, though the films aren\'t as thin, and teflon is quite a bit more expensive as well.

--
Bill Sloman, Sydney

 

[Jan Panteltje]

On a sunny day (Sat, 9 Jul 2022 23:26:05 -0400) it happened Phil Hobbs
<pcdhSpamMeSenseless@electrooptical.net> wrote in
<tadgsd$1eqe$1@gioia.aioe.org>:

Dunno. There are a lot of things that you\'d expect to make good
dielectrics that don\'t. Glass caps, for instance, have soakage that has
to be seen to be believed.

Mica?
Used mica caps in RF years ago.

This about mica is maybe also interesting:
https://www.sciencedaily.com/releases/2022/07/220707100502.htm

 

[Phil Hobbs]

Jan Panteltje wrote:

On a sunny day (Sat, 9 Jul 2022 23:26:05 -0400) it happened Phil Hobbs
pcdhSpamMeSenseless@electrooptical.net> wrote in
tadgsd$1eqe$1@gioia.aioe.org>:

Dunno. There are a lot of things that you\'d expect to make good
dielectrics that don\'t. Glass caps, for instance, have soakage that has
to be seen to be believed.

Mica?
Used mica caps in RF years ago.

This about mica is maybe also interesting:
https://www.sciencedaily.com/releases/2022/07/220707100502.htm

Yup, horrible soakage but great at RF.

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC / Hobbs ElectroOptics
Optics, Electro-optics, Photonics, Analog Electronics
Briarcliff Manor NY 10510

http://electrooptical.net
http://hobbs-eo.com

 

[server]

On Sun, 10 Jul 2022 12:14:35 -0000 (UTC), \"Edward\'s Mother\"
<always.see@post.header> wrote:

No point in discussing anything with Bill \"Bozo\" Sloman, the Australian
troll. Bozo is an incessant liar who cannot be reasoned with. Its fiction
never ends.

He\'s not a conscious liar. But he is in effect delusional.

\"The easiest person to lie to is yourself.\"

Ignore him. Try.

 

[Anthony William Sloman]

On Sunday, July 10, 2022 at 11:28:08 PM UTC+10, jla...@highlandsniptechnology.com wrote:

On Sun, 10 Jul 2022 12:14:35 -0000 (UTC), \"Edward\'s Mother\"
alway...@post.header> wrote:

No point in discussing anything with Bill \"Bozo\" Sloman, the Australian
troll. Bozo is an incessant liar who cannot be reasoned with. Its fiction
never ends.

He\'s not a conscious liar. But he is in effect delusional.

I don\'t share John Larkin\'s delusions about the quality of his posts here. He thinks they deserve flattery. I\'m unkind enough to notice that they don\'t.

This doesn\'t make me \"delusional\" no matter how much John Larkin would like this to be true.

> \"The easiest person to lie to is yourself.\"

John Larkin would know. He tells himself that he knows the truth about anthopogenic global warming when he is actually a sucker for half-witted denialist propaganda.

> Ignore him. Try.

If we could get John Doe to ignore the entire sci.electronics.design user group we\'d all be much happier. John Doe doesn\'t take advice. even John Larkin should have enough sense to have noticed.

--
Bill Sloman, Sydney

 

[Edward Hernandez]

See also these John Doe troll nym-shift names:
John Doe <always.look@message.header>
John <look@post.header>
Judge Dredd <always.look@post.header>
\"Edward\'s Mother\" <always.see@post.header>

How stupid is Troll Doe?

Troll Doe posting one of its vacuous insults at 05:39:20 UTC on 20 Mar
2022 with a grammatical error:

http://al.howardknight.net/?ID=164790428800

Then, at 05:55:56 UTC, 16 minutes and 36 seconds later, Troll Doe
responds to its own post with a correction, but stupidly forgets that it
sets a Followup-To: header to the \"alt.test.group\", resulting in its
correction article posting only to \"alt.test.group\":

http://al.howardknight.net/?ID=164790440700

Troll Doe, mister \"always.look@message.header\", is so stupid it does not
even remember it sets a Followup-To: header in its own vacuous insults.

Special thanks to corvid <bl@ckb.ird> for pointing out the stupidity of
Troll Doe:

http://al.howardknight.net/?ID=165594737000

The Troll Doe stated the following in message-id
<sdhn7c$pkp$4@dont-email.me>:

> The troll doesn\'t even know how to format a USENET post...

And yet, the clueless Troll Doe has continued to post incorrectly
formatted USENET articles that are devoid of content (latest example on
Sun, 10 Jul 2022 12:14:35 -0000 (UTC) in message-id
<taefrb$1cc84$2@dont-email.me>).

NOBODY likes the John Doe troll\'s contentless spam.

This posting is a public service announcement for any google groups
readers who happen by to point out that John Doe does not even follow
the rules it uses to troll other posters.

z5pNGmevyrwN