*gasp* Useful EDN article on tantalum caps
in [Design]
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From: Mycelium on 9 Jun 2010 19:42 On Fri, 04 Jun 2010 09:40:32 -0700, John Larkin <jjlarkin(a)highNOTlandTHIStechnologyPART.com> wrote: >On Fri, 04 Jun 2010 09:29:31 -0700, Mycelium ><mycelium(a)thematrixattheendofthemushroomstem.org> wrote: > >>On Fri, 04 Jun 2010 10:59:32 -0500, Jim Yanik <jyanik(a)abuse.gov> wrote: >> >>> >>>TEKTRONIX used tantalums for many years in their scopes,and the failures >>>were not objectionably high. Usage was mostly on power rails,BTW. >> >> Yeah, except that they also used mostly mil spec components and >>production methodologies back then as well, and one (an engineer) could >>rely on the fact that they had been thoroughly conditioned before use on >>the production line. >> >> A hermetically sealed mil EL cap has a shelf life of decades. A COTS >>EL cap does not. There are several mechanisms that are/were in place >>during their manufacture to ensure that reliability level on those >>specialized caps, even though they differ little at the >>physical/electrical level... ie they are both paste laminated foil >>roll-ups. > >Wet-slugs don't detonate like MnO2 dry tantalums. The MIL CLR-types >are very reliable. They have silver cases, so have gotten expensive. > >I don't think these are roll-ups. They are a sintered tantalum slug >floating in a conductive paste, in a silver can. The semi-liquid paste >must put the fires out. > >John > http://www.evanscap.com/hycap.htm
From: John Larkin on 9 Jun 2010 19:44 On Wed, 09 Jun 2010 16:42:09 -0700, Mycelium <mycelium(a)thematrixattheendofthemushroomstem.org> wrote: >On Fri, 04 Jun 2010 09:40:32 -0700, John Larkin ><jjlarkin(a)highNOTlandTHIStechnologyPART.com> wrote: > >>On Fri, 04 Jun 2010 09:29:31 -0700, Mycelium >><mycelium(a)thematrixattheendofthemushroomstem.org> wrote: >> >>>On Fri, 04 Jun 2010 10:59:32 -0500, Jim Yanik <jyanik(a)abuse.gov> wrote: >>> >>>> >>>>TEKTRONIX used tantalums for many years in their scopes,and the failures >>>>were not objectionably high. Usage was mostly on power rails,BTW. >>> >>> Yeah, except that they also used mostly mil spec components and >>>production methodologies back then as well, and one (an engineer) could >>>rely on the fact that they had been thoroughly conditioned before use on >>>the production line. >>> >>> A hermetically sealed mil EL cap has a shelf life of decades. A COTS >>>EL cap does not. There are several mechanisms that are/were in place >>>during their manufacture to ensure that reliability level on those >>>specialized caps, even though they differ little at the >>>physical/electrical level... ie they are both paste laminated foil >>>roll-ups. >> >>Wet-slugs don't detonate like MnO2 dry tantalums. The MIL CLR-types >>are very reliable. They have silver cases, so have gotten expensive. >> >>I don't think these are roll-ups. They are a sintered tantalum slug >>floating in a conductive paste, in a silver can. The semi-liquid paste >>must put the fires out. >> >>John >> > >http://www.evanscap.com/hycap.htm $88 each. Cool. John
From: Mycelium on 9 Jun 2010 20:13 On Wed, 09 Jun 2010 16:44:48 -0700, John Larkin <jjlarkin(a)highNOTlandTHIStechnologyPART.com> wrote: >$88 each. Cool. So, you can read ads and do math. Me too.
From: Mycelium on 9 Jun 2010 20:16 On Wed, 09 Jun 2010 16:44:48 -0700, John Larkin <jjlarkin(a)highNOTlandTHIStechnologyPART.com> wrote: >On Wed, 09 Jun 2010 16:42:09 -0700, Mycelium ><mycelium(a)thematrixattheendofthemushroomstem.org> wrote: >> >>http://www.evanscap.com/hycap.htm > >$88 each. Cool. > >John > Made in the USA for the use of USA customers only. Keep a hard working US cap maker employed today, buy Evans' capacitors!
From: JosephKK on 11 Jun 2010 17:31
On Fri, 04 Jun 2010 11:24:46 -0400, Phil Hobbs <pcdhSpamMeSenseless(a)electrooptical.net> wrote: >On 6/4/2010 10:04 AM, John Larkin wrote: >> On Fri, 04 Jun 2010 09:47:43 -0400, Phil Hobbs >> <pcdhSpamMeSenseless(a)electrooptical.net> wrote: >> >>> Stupid title, but actual useful info on tantalum cap behaviour: >>> >>> http://www.edn.com/article/509092-What_a_cap_astrophe_.php >>> >>> Now that there's this existence proof, maybe there'll be a bit >>> more...perhaps someone will write them another useful article, e.g. a >>> compendium of all two-transistor circuits. >>> >>> Cheers >>> >>> Phil Hobbs >> >> Tantalums fail from excess current, namely dV/dt. MnO2 is an oxidizer >> and tantalum is a fuel, and only a tiny ignition source sets it off. >> They are fine for current-limited applications but firebombs if used >> to bypass power rails. Derate them 3:1 on voltage if you must use them >> as power bypasses. Better yet use aluminums, polymer aluminums for >> wide-temperature appls >> >> John >> > >The interesting thing in the article is that soldering makes large tants >vulnerable to overvoltage failure well below their rating, and that they >can be reconditioned (and made much more reliable) by putting a current >limit on the power supply. That's more useful for repairs or fixing >problems with a shipping product than for new designs, admittedly. >Still, I thought it was kind of cool, and remarkable for being in EDN! > >Cheers > >Phil Hobbs I kind of have to agree, i haven't seen or heard of much stuff that useful in EDN for over 40 years. Of course i have not been a subscriber for over 25 years over the lack of content. |