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
Electronic components aging
Started by ●October 15, 2013
Reply by ●October 15, 20132013-10-15
On a sunny day (Tue, 15 Oct 2013 12:50:39 +0200) it happened Piotr Wyderski <peter.pan@neverland.mil> wrote in <l3j6m1$nkp$1@node2.news.atman.pl>:>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.[Tin] whiskers old AF118?, but never had problem with modern stuff. FLASH memory WILL fail, if you use it or not. (Cosmic rays, leakage, migration of atoms in silicon, what not. I have noticed FLASH corruption. Same for EPROMs (anybody still uses those?) and EEPROM, optical media. With ever smaller, like 14 micron etc, technology chips, these things will cause errors too. LEDs degrade, high power ones maybe faster (flurescent layer in white ones maybe even more). Displays degrade, OLED will live rather short, expect color tracking errors in OLEDs that use different color material for differrent color pixels, the white ones with filters will do better. Batteries, if you cannot get them anymore it could mean the end of your gadget, Often not user replacable... Standards, change al the time, today's stuff may not work at all with stuff 10 years in the future (connectors, protocols, encryption, I have seen it all). I think the idea is that people should buy new stuff as often as possible, things should stop working and be un-reparable 1 day after the minimum legal required guarantee ends. This is all so we designers have work, and can design ever more new crap. Housings, will be designed bio-degradable, no kidding the plastic of my Creative Labs mp3 player is falling apart already, wonder where they got that bad pastic from.. The list is much longer, but hey, this should get you started. Legal: Your design can no longer be used, it uses more than 10 uW in standby, etc etc.. hehe ;-)> Best regards, Piotr >
Reply by ●October 15, 20132013-10-15
On Tue, 15 Oct 2013 12:50:39 +0200, Piotr Wyderski <peter.pan@neverland.mil> 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, PiotrOptocouplers -- Boris
Reply by ●October 15, 20132013-10-15
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. 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. 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? -- ******************************************************************** Paul E. Bennett IEng MIET.....<email://Paul_E.Bennett@topmail.co.uk> Forth based HIDECS Consultancy.............<http://www.hidecs.co.uk> Mob: +44 (0)7811-639972 Tel: +44 (0)1235-510979 Going Forth Safely ..... EBA. www.electric-boat-association.org.uk.. ********************************************************************
Reply by ●October 15, 20132013-10-15
Piotr Wyderski schrieb:> 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 aboveHello, they are almost immortal if there are no fast and frequent and large temperature changes and if oxygen has no access. Bye
Reply by ●October 15, 20132013-10-15
On 15/10/2013 6:50 PM, 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, PiotrConnectors & IC sockets. Relays.
Reply by ●October 15, 20132013-10-15
On Tue, 15 Oct 2013 12:50:39 +0200, Piotr Wyderski <peter.pan@neverland.mil> 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?"One way of examining this is to look for cards returning from systems replaced by modern systems. Look for the date codes (YYWW) for the youngest chip on the card to get some idea when the card was made. While it might be hard to get such information from companies active in the industrial technology field for decades, you might be convinced them to use allow such figures "how good devices we are (still ??) making" to be published.
Reply by ●October 15, 20132013-10-15
Piotr Wyderski <peter.pan@neverland.mil> 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.Large soldered connections on PCBs. Things like high current transformer tags and automotive-grade interconnectors. The pads always seem to develop circular cracks and go intermittently O/C. -- ~ Adrian Tuddenham ~ (Remove the ".invalid"s and add ".co.uk" to reply) www.poppyrecords.co.uk
Reply by ●October 15, 20132013-10-15
On Tue, 15 Oct 2013 08:35:53 -0400, Boris Mohar <borism_void_@sympatico.ca> wrote:>On Tue, 15 Oct 2013 12:50:39 +0200, Piotr Wyderski <peter.pan@neverland.mil> >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 > >OptocouplersShould last a long time if the LED current is kept low. Integrated current and high temperature degrade the LED. Design for degraded CTR, too. -- 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 15, 20132013-10-15
On Tue, 15 Oct 2013 12:50:39 +0200, Piotr Wyderski <peter.pan@neverland.mil> 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?"Keep power dissipation and currents low in semiconductors. Current causes electromigration. Heat wrecks everything. Use copper pours to keep temps down. Keep PCBs cool and heat-sink parts like FPGAs to power pours. Derate resistor power dissipation, and use copper-pour heat sinks. Use resistors in parallel to spread out heat. That minimizes FR4 degradation from resistor heat. For power, use wirewound resistors spaced away from the PCB. Use stainless hardware, so fasteners don't rust. FR4 will cold-flow under pressure, so don't do things like bolt lugs to boards. Avoid fans, and assume dust. Avoid all-silicon current paths, and don't make direct connection between silicon and the outside world. If you have to use aluminum electrolytics, derate voltage and overkill on capacitance, and buy good ones. Keep them cool. Beware of fuse fatigue. Don't trust surface-mount polyfuses to work anywhere near specs. -- 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
