https://www.eevblog.com/forum/metrology/film-and-ceramic-capacitor-leakage-current/ Tim -- Seven Transistor Labs, LLC Electrical Engineering Consultation and Design Website: https://www.seventransistorlabs.com/
Some capacitor leakage measurements
Started by ●June 14, 2020
Reply by ●June 14, 20202020-06-14
On Sun, 14 Jun 2020 06:31:12 -0500, "Tim Williams" <tiwill@seventransistorlabs.com> wrote:>https://www.eevblog.com/forum/metrology/film-and-ceramic-capacitor-leakage-current/ > >TimHere are a few things I've measured, not general but as needed. https://www.dropbox.com/sh/m0m2zjljysms4yc/AACA2-BIGYDgHNRQN0PuaQOAa?dl=0 -- John Larkin Highland Technology, Inc Science teaches us to doubt. Claude Bernard
Reply by ●June 14, 20202020-06-14
On 2020-06-14 07:31, Tim Williams wrote:> https://www.eevblog.com/forum/metrology/film-and-ceramic-capacitor-leakage-current/ >He had me going for awhile there, till I saw that he was using gigundo COGs like 220 nF. ;) The bad ones were mostly Kemet. These days I don't seem to use a lot of Kemet capacitors compared with Samsung, Murata, and TDK. Kemet does have a quite decent characteristics browser that even has SPICE models. (Dunno how good they are.) 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
Reply by ●June 14, 20202020-06-14
Tim Williams <tiwill@seventransistorlabs.com> wrote:> https://www.eevblog.com/forum/metrology/film-and-ceramic-capacitor-leakage-current/ >It is often hard to measure leakage current and not dielectric relaxation currents... Bye -- Uwe Bonnes bon@elektron.ikp.physik.tu-darmstadt.de Institut fuer Kernphysik Schlossgartenstrasse 9 64289 Darmstadt --------- Tel. 06151 1623569 ------- Fax. 06151 1623305 ---------
Reply by ●June 14, 20202020-06-14
On Sunday, June 14, 2020 at 11:30:17 AM UTC-4, Phil Hobbs wrote:> On 2020-06-14 07:31, Tim Williams wrote: > > https://www.eevblog.com/forum/metrology/film-and-ceramic-capacitor-leakage-current/ > > > > > He had me going for awhile there, till I saw that he was using gigundo > COGs like 220 nF. ;) > > The bad ones were mostly Kemet. These days I don't seem to use a lot of > Kemet capacitors compared with Samsung, Murata, and TDK. Kemet does > have a quite decent characteristics browser that even has SPICE models. > (Dunno how good they are.)Well since he tested only one batch you can always worry that he got a 'good' batch of TDKs and some worse kemets. There were some comparison graphs of COGs in AoE with some better and some worse... but only IDed as brand a,b and c... or some such. I do (did) use a lot of those big 10 uF Panasonic film caps. George H.> > 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
Reply by ●June 14, 20202020-06-14
On 14 Jun 2020 15:42:23 GMT, Uwe Bonnes <bon@hertz.ikp.physik.tu-darmstadt.de> wrote:>Tim Williams <tiwill@seventransistorlabs.com> wrote: >> https://www.eevblog.com/forum/metrology/film-and-ceramic-capacitor-leakage-current/ >> >It is often hard to measure leakage current and not dielectric >relaxation currents... > >ByeRight. Leakage can take seconds to days to settle down, so there may be no simple value. -- John Larkin Highland Technology, Inc Science teaches us to doubt. Claude Bernard
Reply by ●June 14, 20202020-06-14
On Sun, 14 Jun 2020 08:53:07 -0700 (PDT), George Herold <ggherold@gmail.com> wrote:>On Sunday, June 14, 2020 at 11:30:17 AM UTC-4, Phil Hobbs wrote: >> On 2020-06-14 07:31, Tim Williams wrote: >> > https://www.eevblog.com/forum/metrology/film-and-ceramic-capacitor-leakage-current/ >> > >> >> >> He had me going for awhile there, till I saw that he was using gigundo >> COGs like 220 nF. ;) >> >> The bad ones were mostly Kemet. These days I don't seem to use a lot of >> Kemet capacitors compared with Samsung, Murata, and TDK. Kemet does >> have a quite decent characteristics browser that even has SPICE models. >> (Dunno how good they are.) >Well since he tested only one batch you can always worry that he >got a 'good' batch of TDKs and some worse kemets. > >There were some comparison graphs of COGs in AoE with some better >and some worse... but only IDed as brand a,b and c... or some such. > >I do (did) use a lot of those big 10 uF Panasonic film caps. > >George H. >Somebody here once measured self-discharge of some film caps, over years. I recall discharge levels something like one per cent per year. I measured one supercap that had a discharge tau of a few months. The gate voltage of a decent mosfet will stay put, unconnected, for days. Leakages are not many electrons per second. -- John Larkin Highland Technology, Inc Science teaches us to doubt. Claude Bernard
Reply by ●June 14, 20202020-06-14
On Sunday, June 14, 2020 at 12:10:34 PM UTC-4, jla...@highlandsniptechnology.com wrote:> On Sun, 14 Jun 2020 08:53:07 -0700 (PDT), George Herold > <ggherold@gmail.com> wrote: > > >On Sunday, June 14, 2020 at 11:30:17 AM UTC-4, Phil Hobbs wrote: > >> On 2020-06-14 07:31, Tim Williams wrote: > >> > https://www.eevblog.com/forum/metrology/film-and-ceramic-capacitor-leakage-current/ > >> > > >> > >> > >> He had me going for awhile there, till I saw that he was using gigundo > >> COGs like 220 nF. ;) > >> > >> The bad ones were mostly Kemet. These days I don't seem to use a lot of > >> Kemet capacitors compared with Samsung, Murata, and TDK. Kemet does > >> have a quite decent characteristics browser that even has SPICE models. > >> (Dunno how good they are.) > >Well since he tested only one batch you can always worry that he > >got a 'good' batch of TDKs and some worse kemets. > > > >There were some comparison graphs of COGs in AoE with some better > >and some worse... but only IDed as brand a,b and c... or some such. > > > >I do (did) use a lot of those big 10 uF Panasonic film caps. > > > >George H. > > > > Somebody here once measured self-discharge of some film caps, over > years.Tom Bruhns. e.g.: <quote> From: k7...@aol.com (Tom Bruhns) Newsgroups: sci.electronics.design Subject: Re: Measuring leakage current of Capacitors Date: 18 Jul 2002 18:16:17 -0700 wavefront@SPAMbigfoot.com (Martin Griffith) wrote in message news:<3d36e08f...@news.btopenworld.com>... ... > > > do a search for in google groups > > From: Tom Bruhns <to...@lsid.hp.com> > Newsgroups: sci.electronics.design > Subject: On capacitor self-timeconstants > Date: Thu, 29 Jul 1999 13:39:05 -0700 > > jolly good stuff......... Blush... I'm flattered you've kept that around, Martin. I should tell you, though, I've kept the little board with the caps still soldered to it. They are still discharging. It's been a while since I measured them, but the last time I did, some two years after they'd been charged, the apparent time constants were on the order of 50 years for the polypropylenes, and about 2.5 years for the polyesters (Mylars). Since it's been about 9 months since I last measured them, it's about time for another measurement. I'll try to remember to do that and post more complete results in the near future. Modern polyprops are pretty darned low leakage! Cheers, Tom <quote> (How I remember such stuff so easily is a mystery to me, but it comes in handy.)> I recall discharge levels something like one per cent per year. > > I measured one supercap that had a discharge tau of a few months. > > The gate voltage of a decent mosfet will stay put, unconnected, for > days. Leakages are not many electrons per second.Cheers, James
Reply by ●June 14, 20202020-06-14
<jlarkin@highlandsniptechnology.com> wrote in message news:ecicefd41ri9505a8nqqd8sfr9kttdnuvo@4ax.com...> Right. Leakage can take seconds to days to settle down, so there may > be no simple value.Or weeks for supercaps (in regards to the last entry in your other post's link). Which seem to retain voltage quite well (many months) well below threshold. At room temp. Means a generous derating (say 1.5-2V nominal out of a 2.7V rating) but still handy for some applications. Tim -- Seven Transistor Labs, LLC Electrical Engineering Consultation and Design Website: https://www.seventransistorlabs.com/
Reply by ●June 14, 20202020-06-14
jla...@highlandsniptechnology.com wrote: =========================================> > Somebody here once measured self-discharge of some film caps, over > years. I recall discharge levels something like one per cent per year. >** Must have been some large value polystyrene types. Lowest tempco and leakage of any film cap. .... Phil
