John Larkin schrieb:> > We've used zillions (well, maybe 20,000) Fujitsu sealed DPDT telecom > type relays, as cal bus and range switches. They are very reliable.Hello, but relays with open contacts exposed to the air are not very reliable over a long time. Cleaning them may help, but only for some more years. Bye
Electronic components aging
Started by ●October 15, 2013
Reply by ●October 16, 20132013-10-16
Reply by ●October 16, 20132013-10-16
On 2013-10-15, edward.ming.lee@gmail.com <edward.ming.lee@gmail.com> wrote:> >> >> Avoid all-silicon current paths, and don't make direct connection between >> silicon and the outside world. > > That means one thing: Plain Old Relays. How long can sealed relays be expected to last, if we only fire it up occasionally? Perhaps one in weeks.Datasheets typically quote a million on-off cycles at 1/5 rated current ,resistive load -- ⚂⚃ 100% natural --- news://freenews.netfront.net/ - complaints: news@netfront.net ---
Reply by ●October 16, 20132013-10-16
On 15/10/2013 21:50, Piotr Wyderski wrote:> Speaking of high reliability... I think that it is often > a somewhat neglected issue, so I start this thread as a > mean to collect *practical* observations for people who > care about long MTBF. In other words, "if I had to build > a device which should last 50 years, I would... what?" > > Resistors (if not overloaded): immortal > > Ceramic capacitors: as above > Tantalum/nobium caps: ? > > Electrolytic caps: disaster area > > Transistors, diodes and ICs: the silicon die should not > degrade, but how about the endurance of the resin? > At least some early Polish ICs had problems here: > the thermal coefficient of the casing was not well-matched > and power cycling finally broke the bonding wires. > There were some moisture absorbtion problems, too. > Is it still an issue? > > BGA: it can be expected that thermal cycling will > eventually destroy the balls, as there are no "springs" > to absorb thermal stresses. Gull wings are much better here. > > FR4: ? > > Soldering: the EU has done a lot in order to make > the newer devices not very reliable as a consequence > of the RoHS directive. I see nothing wrong with the > old SnPb joints, the old boards look healthy. > > Conformal coating: ? > > Wires: ? > > Please add your comments. > > Best regards, PiotrI have thought about a similar problem from time to time, except that I was thinking of designing something for maybe 1000 years or more of storage followed by being expected to operate. I assumed that the whole equipment should be hermetically encapsulated and put somewhere cool, so I'm only thinking about inherent aging. I think larger geometry chips may well be ok (provided they don't rely on stored charge like EPROMS and FLASH). (Also I think the patterns of metal in a chip that is passivated with oxide might well be visible after many thousands of years, and be a fairly dense and long-lasting way to store information. Because consumer chips also get made in very high volumes and end up discarded in landfils all over the world I expect that it will be possible to find be copies of a few on-chip inductors that I designed even after a very long time.) My guess is that film capacitors like polypropylene might do alright for a long time. I have observed high-K ceramic caps that have lost quite a lot of capacitance even after a few years but they could be restored by reheating when they are re-soldered, (which I consider cheating in this context, unless the equipment can do that itself). Even for much shorter periods, batteries seem to be one of the worst causes of permanent damage due to electrolyte escaping, though I haven't seen a lithium coin cell leak so far. Electrolytic caps seem to be able to last many decades if the equipment is turned on often enough to keep the dielectric formed. If the equipment is just stored for decades with no power applied then the dielectric degrades and if power is then applied suddenly they fail due to overheating, or if they are used in a low current circuit the leakage just makes it not work (maybe only temporarily). Even when the electrolytics are kept formed, it is also necessary to plan for the ESR to increase and the capacitance to decrease, otherwise the circuit will not last long. I recall reading that inductors (chokes) used to be connected such that the fine wire was more negative than the iron core, rather than the other way around, so that any moisture didn't cause electrolytic corrosion of the thin wire if there were cracks in the enamel. I have seen neodymium magnets which didn't last long (plating fell off and magnet turned to powder) though I have seen others that didn't have that problem. I suspect that hermetic metal can tantalum capacitors have different reliability from the dipped style and perhaps the surface mount ones are different again. I have had a dipped tantalum cap go short circuit in an always-on battery charger application (trickle charger fed from a large series resistor) where I don't think it was ever subjected to high dv/dt. Desinging in redundancy would help a lot, and if the redundant copies are different and each avoid using a different type/brand of component, that might help against the difficulty of predicting failure mechanisms. I found this project slightly interesting, though I wouldn't have done it the same way: http://longnow.org/clock/ Chris
Reply by ●October 16, 20132013-10-16
On Wed, 16 Oct 2013 09:58:11 +0200, Uwe Hercksen <hercksen@mew.uni-erlangen.de> wrote:> > >John Larkin schrieb: >> >> We've used zillions (well, maybe 20,000) Fujitsu sealed DPDT telecom >> type relays, as cal bus and range switches. They are very reliable. > >Hello, > >but relays with open contacts exposed to the air are not very reliable >over a long time. Cleaning them may help, but only for some more years. > >ByeThe relays that we use are sealed. -- John Larkin Highland Technology Inc www.highlandtechnology.com jlarkin at highlandtechnology dot com Precision electronic instrumentation Picosecond-resolution Digital Delay and Pulse generators Custom timing and laser controllers Photonics and fiberoptic TTL data links VME analog, thermocouple, LVDT, synchro, tachometer Multichannel arbitrary waveform generators
Reply by ●October 16, 20132013-10-16
"Chris Jones" <lugnut808@spam.yahoo.com> wrote in message news:525e8921$0$1497$862e30e2@ngroups.net...> I suspect that hermetic metal can tantalum capacitors have different > reliability from the dipped style and perhaps the surface mount ones are > different again.I don't know about the dry type (being mil spec, hopefully their failure modes are well understood and controlled), but there is also a wet type (which also has very low leakage, once stabilized). Tim -- Seven Transistor Labs Electrical Engineering Consultation Website: http://seventransistorlabs.com
Reply by ●October 16, 20132013-10-16
Paul E Bennett wrote:> Piotr Wyderski wrote: > >> Speaking of high reliability... I think that it is often >> a somewhat neglected issue, so I start this thread as a >> mean to collect *practical* observations for people who >> care about long MTBF. In other words, "if I had to build >> a device which should last 50 years, I would... what?" > > With the best will in the world, there is no electronics based technology > that will last that long. It is hard enough doing designs that are required > to have a life of 20 or 25 years with minimal (no) maintenance. After that > time the equipment is replaced in major refurbishment programmes. >Can you talk to the electronics in our Hammond organ about that? It is 53 years old now and no signs of fatigure. First set of tubes. Then there is the Sachsenwerk radio from 1939. When I donated it to a museum a couple of years ago it ran just fine and likely still does.> Any component that relies on the long term stabiliity of chemistry will > degrade and fail eventually. Even in the mechanical world metals like Iron > and Stainless Steel will change over time. >Depends on how well the components are built they can easily outlast humans. I have a radio with the first "IC" in there from the roaring 20's. Last time I fired it up was over 15 years ago but it worked: http://www.radiomuseum.org/tubes/tube_3nf.html You can still buy it used: http://www.ebay.com/itm/GERMAN-RADIO-RECEIVER-LOEWE-OE333-with-3NF-TUBE-C1927-/330954445929 Or look at the DC-3. It's still hauling lots of freight and passengers. These old airplanes are used for hard jobs, I think this one was built in 1937: https://www.youtube.com/watch?v=jx11k1r1Pm8> Only in software can you achieve really long lifetimes (if you are careful > about your design) but then what would you have left to run it on? >My dad's old IBM 5100 from the mid-70's is still there :-) -- Regards, Joerg http://www.analogconsultants.com/
Reply by ●October 16, 20132013-10-16
Hi Paul, On 10/15/2013 5:40 AM, Paul E Bennett wrote:> Piotr Wyderski wrote:> Only in software can you achieve really long lifetimes (if you are careful > about your design) but then what would you have left to run it on?That's the problem. You can try to maintain legacy iron for this purpose. Or, write a VM to host it. But, hardly "cheap" or "sure fire" solutions... [Anyone have a GE-645 emulator to run the original Mutt-Licks binaries?? :-/ And that's just *barely* 50 years! ]
Reply by ●October 17, 20132013-10-17
On 10/15/2013 3:50 AM, Piotr Wyderski wrote:> Speaking of high reliability... I think that it is often > a somewhat neglected issue, so I start this thread as a > mean to collect *practical* observations for people who > care about long MTBF. In other words, "if I had to build > a device which should last 50 years, I would... what?" > > Resistors (if not overloaded): immortal > > Ceramic capacitors: as above > Tantalum/nobium caps: ? > > Electrolytic caps: disaster area > > Transistors, diodes and ICs: the silicon die should not > degrade, but how about the endurance of the resin? > At least some early Polish ICs had problems here: > the thermal coefficient of the casing was not well-matched > and power cycling finally broke the bonding wires. > There were some moisture absorbtion problems, too. > Is it still an issue? > > BGA: it can be expected that thermal cycling will > eventually destroy the balls, as there are no "springs" > to absorb thermal stresses. Gull wings are much better here. > > FR4: ? > > Soldering: the EU has done a lot in order to make > the newer devices not very reliable as a consequence > of the RoHS directive. I see nothing wrong with the > old SnPb joints, the old boards look healthy. > > Conformal coating: ? > > Wires: ? > > Please add your comments. > > Best regards, PiotrMosfets have a threshold voltage shift related to how many times they are switched. The rule of thumb is your chip should be able to last 10 years at the maximum clock frequency. But of course, this isn't hard and fast or even written down. Basically a logic circuit will still work if the fet threshold voltage changes over time. But if there is some critical timing and the fet threshold voltage got larger, it will have less drive and thus the chip becomes slower. The threshold shift effect has been around since the 1um days. I believe it is related to hot carriers. All sorts of foo was created over the years to keep this problem tolerable.
Reply by ●October 17, 20132013-10-17
Chris Jones wrote:> On 15/10/2013 21:50, Piotr Wyderski wrote: >> Speaking of high reliability... I think that it is often >> a somewhat neglected issue, so I start this thread as a >> mean to collect *practical* observations for people who >> care about long MTBF. In other words, "if I had to build >> a device which should last 50 years, I would... what?" >> >> Resistors (if not overloaded): immortal >> >> Ceramic capacitors: as above >> Tantalum/nobium caps: ? >> >> Electrolytic caps: disaster area >> >> Transistors, diodes and ICs: the silicon die should not >> degrade, but how about the endurance of the resin? >> At least some early Polish ICs had problems here: >> the thermal coefficient of the casing was not well-matched >> and power cycling finally broke the bonding wires. >> There were some moisture absorbtion problems, too. >> Is it still an issue? >> >> BGA: it can be expected that thermal cycling will >> eventually destroy the balls, as there are no "springs" >> to absorb thermal stresses. Gull wings are much better here. >> >> FR4: ? >> >> Soldering: the EU has done a lot in order to make >> the newer devices not very reliable as a consequence >> of the RoHS directive. I see nothing wrong with the >> old SnPb joints, the old boards look healthy. >> >> Conformal coating: ? >> >> Wires: ? >> >> Please add your comments. >> >> Best regards, Piotr > > I have thought about a similar problem from time to time, except that I > was thinking of designing something for maybe 1000 years or more of > storage followed by being expected to operate. I assumed that the whole > equipment should be hermetically encapsulated and put somewhere cool, so > I'm only thinking about inherent aging. > > I think larger geometry chips may well be ok (provided they don't rely > on stored charge like EPROMS and FLASH). (Also I think the patterns of > metal in a chip that is passivated with oxide might well be visible > after many thousands of years, and be a fairly dense and long-lasting > way to store information. Because consumer chips also get made in very > high volumes and end up discarded in landfils all over the world I > expect that it will be possible to find be copies of a few on-chip > inductors that I designed even after a very long time.) > > My guess is that film capacitors like polypropylene might do alright for > a long time. > > I have observed high-K ceramic caps that have lost quite a lot of > capacitance even after a few years but they could be restored by > reheating when they are re-soldered, (which I consider cheating in this > context, unless the equipment can do that itself). > > Even for much shorter periods, batteries seem to be one of the worst > causes of permanent damage due to electrolyte escaping, though I haven't > seen a lithium coin cell leak so far. > > Electrolytic caps seem to be able to last many decades if the equipment > is turned on often enough to keep the dielectric formed. If the > equipment is just stored for decades with no power applied then the > dielectric degrades and if power is then applied suddenly they fail due > to overheating, or if they are used in a low current circuit the leakage > just makes it not work (maybe only temporarily). Even when the > electrolytics are kept formed, it is also necessary to plan for the ESR > to increase and the capacitance to decrease, otherwise the circuit will > not last long. > > I recall reading that inductors (chokes) used to be connected such that > the fine wire was more negative than the iron core, rather than the > other way around, so that any moisture didn't cause electrolytic > corrosion of the thin wire if there were cracks in the enamel. > > I have seen neodymium magnets which didn't last long (plating fell off > and magnet turned to powder) though I have seen others that didn't have > that problem. > > I suspect that hermetic metal can tantalum capacitors have different > reliability from the dipped style and perhaps the surface mount ones are > different again. I have had a dipped tantalum cap go short circuit in an > always-on battery charger application (trickle charger fed from a large > series resistor) where I don't think it was ever subjected to high dv/dt. > > Desinging in redundancy would help a lot, and if the redundant copies > are different and each avoid using a different type/brand of component, > that might help against the difficulty of predicting failure mechanisms. > > I found this project slightly interesting, though I wouldn't have done > it the same way: > http://longnow.org/clock/ > > Chris >A number of stupid people have totally wasted their time and money here. Plain old WEAR is going to put a severe crimp in that impossible 10K year "timeframe".
Reply by ●October 17, 20132013-10-17
On Tue, 15 Oct 2013 13:40:24 +0100, Paul E Bennett <Paul_E.Bennett@topmail.co.uk> wrote:>Piotr Wyderski wrote: > >> Speaking of high reliability... I think that it is often >> a somewhat neglected issue, so I start this thread as a >> mean to collect *practical* observations for people who >> care about long MTBF. In other words, "if I had to build >> a device which should last 50 years, I would... what?" > >With the best will in the world, there is no electronics based =technology=20>that will last that long. It is hard enough doing designs that are =required=20>to have a life of 20 or 25 years with minimal (no) maintenance. After =that=20>time the equipment is replaced in major refurbishment programmes. > >Any component that relies on the long term stabiliity of chemistry will=20 >degrade and fail eventually. Even in the mechanical world metals like =Iron=20>and Stainless Steel will change over time. > >Only in software can you achieve really long lifetimes (if you are =careful=20>about your design) but then what would you have left to run it on?Try looking at some serious long term infrastructure systems. There is plenty of SCADA that has already lasted as much as 60 years or more. = Lots more in heavy industries (refining, major metal mills, chemical plants, water treatment, wastewater treatment, etc.,) where replacement costs get really really big. ?-)
