*gasp* Useful EDN article on tantalum caps
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From: Glenn Gundlach on 4 Jun 2010 19:15 On Jun 4, 2:10 pm, John Larkin <jjlar...(a)highNOTlandTHIStechnologyPART.com> wrote: > On Fri, 04 Jun 2010 13:25:20 -0700, Joerg <inva...(a)invalid.invalid> > wrote: > > > > >John Larkin wrote: > >> On Fri, 04 Jun 2010 09:53:36 -0700, "Paul Hovnanian P.E." > >> <p...(a)hovnanian.com> wrote: > > >>> Phil Hobbs wrote: > > >>>> On 6/4/2010 10:04 AM, John Larkin wrote: > >>>>> On Fri, 04 Jun 2010 09:47:43 -0400, Phil Hobbs > >>>>> <pcdhSpamMeSensel...(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! > >>> That might make a good argument for a properly thought out burn in > >>> procedure. There's too much pressure from management to just build it and > >>> ship it (airplanes included). > > >> We've had tantalums fail months or years after a product was shipped. > >> On one of our VME modules, which we do burn in, well over half the > >> field failures were tantalum caps. Field MTBF increased by about 3: 1 > >> when we fixed that problem. > > >> This is more an engineering issue than a test/burnin thing. Dry > >> tantalums have to be designed in very carefully, and the manufacturers > >> mostly don't want to tell you what's safe or not safe. > > >Sounds just like LDOs :-) > > Lots of LDOs need tantalum output caps to be stable. It's a > conspiracy. > > John How do polymer caps stack up? G²
From: John Larkin on 4 Jun 2010 19:22 On Fri, 4 Jun 2010 16:15:49 -0700 (PDT), Glenn Gundlach <stratus46(a)yahoo.com> wrote: >On Jun 4, 2:10�pm, John Larkin ><jjlar...(a)highNOTlandTHIStechnologyPART.com> wrote: >> On Fri, 04 Jun 2010 13:25:20 -0700, Joerg <inva...(a)invalid.invalid> >> wrote: >> >> >> >> >John Larkin wrote: >> >> On Fri, 04 Jun 2010 09:53:36 -0700, "Paul Hovnanian P.E." >> >> <p...(a)hovnanian.com> wrote: >> >> >>> Phil Hobbs wrote: >> >> >>>> On 6/4/2010 10:04 AM, John Larkin wrote: >> >>>>> On Fri, 04 Jun 2010 09:47:43 -0400, Phil Hobbs >> >>>>> <pcdhSpamMeSensel...(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! >> >>> That might make a good argument for a properly thought out burn in >> >>> procedure. There's too much pressure from management to just build it and >> >>> ship it (airplanes included). >> >> >> We've had tantalums fail months or years after a product was shipped. > > >> On one of our VME modules, which we do burn in, well over half >the > > >> field failures were tantalum caps. Field MTBF increased by about >3: 1 > > >> when we fixed that problem. > > > > >> This is more an engineering issue than a test/burnin thing. Dry > > >> tantalums have to be designed in very carefully, and the >manufacturers > > >> mostly don't want to tell you what's safe or not safe. > > > > >Sounds just like LDOs :-) > > > > Lots of LDOs need tantalum output caps to be stable. It's a > > conspiracy. > > > > John > >How do polymer caps stack up? > >G� Assuming that's a serious question, and not a terrible pun, they're great, but ESR is so low that some LDOs won't like them. They don't flame like tantalums, don't freeze like aluminums, and I'm not sure about long-term reliability. John
From: George Herold on 4 Jun 2010 23:23 On Jun 4, 7:22 pm, John Larkin <jjlar...(a)highNOTlandTHIStechnologyPART.com> wrote: > On Fri, 4 Jun 2010 16:15:49 -0700 (PDT), Glenn Gundlach > > > > > > <stratu...(a)yahoo.com> wrote: > >On Jun 4, 2:10 pm, John Larkin > ><jjlar...(a)highNOTlandTHIStechnologyPART.com> wrote: > >> On Fri, 04 Jun 2010 13:25:20 -0700, Joerg <inva...(a)invalid.invalid> > >> wrote: > > >> >John Larkin wrote: > >> >> On Fri, 04 Jun 2010 09:53:36 -0700, "Paul Hovnanian P.E." > >> >> <p...(a)hovnanian.com> wrote: > > >> >>> Phil Hobbs wrote: > > >> >>>> On 6/4/2010 10:04 AM, John Larkin wrote: > >> >>>>> On Fri, 04 Jun 2010 09:47:43 -0400, Phil Hobbs > >> >>>>> <pcdhSpamMeSensel...(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! > >> >>> That might make a good argument for a properly thought out burn in > >> >>> procedure. There's too much pressure from management to just build it and > >> >>> ship it (airplanes included). > > >> >> We've had tantalums fail months or years after a product was shipped. > > > >> On one of our VME modules, which we do burn in, well over half > >the > > > >> field failures were tantalum caps. Field MTBF increased by about > >3: 1 > > > >> when we fixed that problem. > > > > >> This is more an engineering issue than a test/burnin thing. Dry > > > >> tantalums have to be designed in very carefully, and the > >manufacturers > > > >> mostly don't want to tell you what's safe or not safe. > > > > >Sounds just like LDOs :-) > > > > Lots of LDOs need tantalum output caps to be stable. It's a > > > conspiracy. > > > > John > > >How do polymer caps stack up? > > >G > > Assuming that's a serious question, and not a terrible pun, they're > great, but ESR is so low that some LDOs won't like them. Can't you add a bit of R? George H. > > They don't flame like tantalums, don't freeze like aluminums, and I'm > not sure about long-term reliability. > > John- Hide quoted text - > > - Show quoted text -
From: Michael A. Terrell on 5 Jun 2010 00:21 George Herold wrote: > > On Jun 4, 7:22 pm, John Larkin > <jjlar...(a)highNOTlandTHIStechnologyPART.com> wrote: > > On Fri, 4 Jun 2010 16:15:49 -0700 (PDT), Glenn Gundlach > > > > > > > > > > > > <stratu...(a)yahoo.com> wrote: > > >On Jun 4, 2:10 pm, John Larkin > > ><jjlar...(a)highNOTlandTHIStechnologyPART.com> wrote: > > >> On Fri, 04 Jun 2010 13:25:20 -0700, Joerg <inva...(a)invalid.invalid> > > >> wrote: > > > > >> >John Larkin wrote: > > >> >> On Fri, 04 Jun 2010 09:53:36 -0700, "Paul Hovnanian P.E." > > >> >> <p...(a)hovnanian.com> wrote: > > > > >> >>> Phil Hobbs wrote: > > > > >> >>>> On 6/4/2010 10:04 AM, John Larkin wrote: > > >> >>>>> On Fri, 04 Jun 2010 09:47:43 -0400, Phil Hobbs > > >> >>>>> <pcdhSpamMeSensel...(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! > > >> >>> That might make a good argument for a properly thought out burn in > > >> >>> procedure. There's too much pressure from management to just build it and > > >> >>> ship it (airplanes included). > > > > >> >> We've had tantalums fail months or years after a product was shipped. > > > > >> On one of our VME modules, which we do burn in, well over half > > >the > > > > >> field failures were tantalum caps. Field MTBF increased by about > > >3: 1 > > > > >> when we fixed that problem. > > > > > > >> This is more an engineering issue than a test/burnin thing. Dry > > > > >> tantalums have to be designed in very carefully, and the > > >manufacturers > > > > >> mostly don't want to tell you what's safe or not safe. > > > > > > >Sounds just like LDOs :-) > > > > > > Lots of LDOs need tantalum output caps to be stable. It's a > > > > conspiracy. > > > > > > John > > > > >How do polymer caps stack up? > > > > >G > > > > Assuming that's a serious question, and not a terrible pun, they're > > great, but ESR is so low that some LDOs won't like them. > > Can't you add a bit of R? L is better for tantalums. -- Anyone wanting to run for any political office in the US should have to have a DD214, and a honorable discharge.
From: Joerg on 5 Jun 2010 12:05
Michael A. Terrell wrote: > George Herold wrote: >> On Jun 4, 7:22 pm, John Larkin >> <jjlar...(a)highNOTlandTHIStechnologyPART.com> wrote: >>> On Fri, 4 Jun 2010 16:15:49 -0700 (PDT), Glenn Gundlach >>> >>> >>> >>> >>> >>> <stratu...(a)yahoo.com> wrote: >>>> On Jun 4, 2:10 pm, John Larkin >>>> <jjlar...(a)highNOTlandTHIStechnologyPART.com> wrote: >>>>> On Fri, 04 Jun 2010 13:25:20 -0700, Joerg <inva...(a)invalid.invalid> >>>>> wrote: >>>>>> John Larkin wrote: >>>>>>> On Fri, 04 Jun 2010 09:53:36 -0700, "Paul Hovnanian P.E." >>>>>>> <p...(a)hovnanian.com> wrote: >>>>>>>> Phil Hobbs wrote: >>>>>>>>> On 6/4/2010 10:04 AM, John Larkin wrote: >>>>>>>>>> On Fri, 04 Jun 2010 09:47:43 -0400, Phil Hobbs >>>>>>>>>> <pcdhSpamMeSensel...(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! >>>>>>>> That might make a good argument for a properly thought out burn in >>>>>>>> procedure. There's too much pressure from management to just build it and >>>>>>>> ship it (airplanes included). >>>>>>> We've had tantalums fail months or years after a product was shipped. >>>> > >> On one of our VME modules, which we do burn in, well over half >>>> the >>>>>>> field failures were tantalum caps. Field MTBF increased by about >>>> 3: 1 >>>>>>> when we fixed that problem. >>>>>>> This is more an engineering issue than a test/burnin thing. Dry >>>>>>> tantalums have to be designed in very carefully, and the >>>> manufacturers >>>>>>> mostly don't want to tell you what's safe or not safe. >>>>>> Sounds just like LDOs :-) >>>>> Lots of LDOs need tantalum output caps to be stable. It's a >>>>> conspiracy. >>>>> John >>>> How do polymer caps stack up? >>>> G >>> Assuming that's a serious question, and not a terrible pun, they're >>> great, but ESR is so low that some LDOs won't like them. >> Can't you add a bit of R? > > > L is better for tantalums. > Z is even better. I'd like one more hour of Z but I have to service the pellet stove today ... -- Regards, Joerg http://www.analogconsultants.com/ "gmail" domain blocked because of excessive spam. Use another domain or send PM. |