On Mon, 11 Dec 2017 19:12:08 GMT, Steve Wilson <no@spam.com> wrote:>Winfield Hill <hill@rowland.harvard.edu> wrote: > >> Mike Perkins wrote... > >>> I'm not in a position to test every component that could >>> run into 1,000 or more, although batch testing might be a compromise. > >> Batch testing should be fine. > >Nobody does AQL any more? > >https://en.wikipedia.org/wiki/Acceptable_quality_limitIt's not practical to test standard parts for AQL. At a few FITs, you'd have to test hundreds of thousands of reels of resistors to verify specified quality. We test a couple of parts on each reel to make sure they are what we ordered. There are a very few parts, like some lasers, where we test every one. But that's not an AQL measurement exactly either. -- John Larkin Highland Technology, Inc picosecond timing precision measurement jlarkin att highlandtechnology dott com http://www.highlandtechnology.com
Low MOSFET IDSS current
Started by ●December 9, 2017
Reply by ●December 11, 20172017-12-11
Reply by ●December 13, 20172017-12-13
On Saturday, December 9, 2017 at 3:07:09 PM UTC-8, Mike Perkins wrote:> Most seem to specify 1uA, even at 25C. Can anyone point me to one that's > affordable and more like 10nA? > > Most selection guides seem to miss out this feature! > > Greatly appreciate any feedback.The specification is what they're tested for. If you want some tiny current specified, the test takes longer, and you'll have to contact the factory for a special order. Or, test 'em yourself. Off-the-shelf high speed testing: cheap, and sloppy. More info here: <http://www.electronicdesign.com/test-amp-measurement/whats-all-femtoampere-stuff-anyhow>
Reply by ●December 13, 20172017-12-13
On Tue, 12 Dec 2017 21:16:18 -0800 (PST), whit3rd <whit3rd@gmail.com> wrote:>On Saturday, December 9, 2017 at 3:07:09 PM UTC-8, Mike Perkins wrote: >> Most seem to specify 1uA, even at 25C. Can anyone point me to one that's >> affordable and more like 10nA? >> >> Most selection guides seem to miss out this feature! >> >> Greatly appreciate any feedback. > >The specification is what they're tested for. If you want some tiny >current specified, the test takes longer, and you'll have to contact the >factory for a special order. Or, test 'em yourself. > >Off-the-shelf high speed testing: cheap, and sloppy. > >More info here: <http://www.electronicdesign.com/test-amp-measurement/whats-all-femtoampere-stuff-anyhow>A common DVM, on a voltage range, can measure low currents. 10 meg input, 100 mV range, is 10 nA full-scale, picoamps resolution. -- John Larkin Highland Technology, Inc picosecond timing precision measurement jlarkin att highlandtechnology dott com http://www.highlandtechnology.com
Reply by ●December 15, 20172017-12-15
John Larkin <jjlarkin@highland_snip_technology.com> wrote:> On Mon, 11 Dec 2017 19:12:08 GMT, Steve Wilson <no@spam.com> wrote:>>Winfield Hill <hill@rowland.harvard.edu> wrote:>>> Mike Perkins wrote...>>>> I'm not in a position to test every component that could run into >>>> 1,000 or more, although batch testing might be a compromise.>>> Batch testing should be fine.>>Nobody does AQL any more?>>https://en.wikipedia.org/wiki/Acceptable_quality_limit> It's not practical to test standard parts for AQL. At a few FITs, > you'd have to test hundreds of thousands of reels of resistors to > verify specified quality.This is very wrong. AQL is a sampling method for incoming inspection. It allows you to pick a sample size for a desired probability that acceptance or rejection of the lot is correct. It saves the cost and time of having to test the entire lot. FIT is "Failure in Time" and is a reliability term. It is defined as a failure rate of 1 per billion hours. It obviously applies after the parts have already been accepted and placed in service. There is a wealth of information available on both on the web.
Reply by ●December 15, 20172017-12-15
On Fri, 15 Dec 2017 10:34:28 GMT, Steve Wilson <no@spam.com> wrote:>John Larkin <jjlarkin@highland_snip_technology.com> wrote: > >> On Mon, 11 Dec 2017 19:12:08 GMT, Steve Wilson <no@spam.com> wrote: > >>>Winfield Hill <hill@rowland.harvard.edu> wrote: > >>>> Mike Perkins wrote... > >>>>> I'm not in a position to test every component that could run into >>>>> 1,000 or more, although batch testing might be a compromise. > >>>> Batch testing should be fine. > >>>Nobody does AQL any more? > >>>https://en.wikipedia.org/wiki/Acceptable_quality_limit > >> It's not practical to test standard parts for AQL. At a few FITs, >> you'd have to test hundreds of thousands of reels of resistors to >> verify specified quality. > >This is very wrong. AQL is a sampling method for incoming inspection. It >allows you to pick a sample size for a desired probability that acceptance >or rejection of the lot is correct. It saves the cost and time of having to >test the entire lot.OK, what sample size to you have to have to verify that you're meeting 1ppb to a 99% confidence level?>FIT is "Failure in Time" and is a reliability term. It is defined as a >failure rate of 1 per billion hours. It obviously applies after the parts >have already been accepted and placed in service.>There is a wealth of information available on both on the web.
Reply by ●December 15, 20172017-12-15
On 12/15/2017 05:34 AM, Steve Wilson wrote:> > FIT is "Failure in Time" and is a reliability term. It is defined as a > failure rate of 1 per billion hours. It obviously applies after the parts > have already been accepted and placed in service.And is used based on the now completely discredited reliability estimation method of MIL-HDBK-217. The idea that the failure rate of a system can be calculated as the sum of tabulated, invariant failure rates of the individual parts is no better than a random number generator. I had to use it back in the early '80s in my satellite radio job, but even the managers there (who were all engineers) agreed it was a joke. "Hey! If I leave out the input protection circuitry, I can reduce the failure rate by 600 FITs! And if I get rid of one of these parallelled MOSFETs, I can save another hundred!" (Not.) 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 https://hobbs-eo.com
Reply by ●December 15, 20172017-12-15
On Fri, 15 Dec 2017 09:55:02 -0500, Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> wrote:>On 12/15/2017 05:34 AM, Steve Wilson wrote: > >> >> FIT is "Failure in Time" and is a reliability term. It is defined as a >> failure rate of 1 per billion hours. It obviously applies after the parts >> have already been accepted and placed in service. > >And is used based on the now completely discredited reliability >estimation method of MIL-HDBK-217. The idea that the failure rate of a >system can be calculated as the sum of tabulated, invariant failure >rates of the individual parts is no better than a random number generator. > >I had to use it back in the early '80s in my satellite radio job, but >even the managers there (who were all engineers) agreed it was a joke. > >"Hey! If I leave out the input protection circuitry, I can reduce the >failure rate by 600 FITs! And if I get rid of one of these parallelled >MOSFETs, I can save another hundred!" (Not.) > >Cheers > >Phil HobbsSome of our customers want an MTBF calculation, based on the mil hbk or Bellcore numbers, so we do it for them. Their quality people are invariably lunatics so we do what we need to to keep them off our case. DGMS on SPC. Most of our products have field failure rates far below the calculations. When one doesn't, there's a reason. Like "it's heavy and customers tend to drop it." -- John Larkin Highland Technology, Inc lunatic fringe electronics
Reply by ●December 15, 20172017-12-15
On 12/15/2017 10:33 AM, John Larkin wrote:> On Fri, 15 Dec 2017 09:55:02 -0500, Phil Hobbs > <pcdhSpamMeSenseless@electrooptical.net> wrote: > >> On 12/15/2017 05:34 AM, Steve Wilson wrote: >> >>> >>> FIT is "Failure in Time" and is a reliability term. It is defined as a >>> failure rate of 1 per billion hours. It obviously applies after the parts >>> have already been accepted and placed in service. >> >> And is used based on the now completely discredited reliability >> estimation method of MIL-HDBK-217. The idea that the failure rate of a >> system can be calculated as the sum of tabulated, invariant failure >> rates of the individual parts is no better than a random number generator. >> >> I had to use it back in the early '80s in my satellite radio job, but >> even the managers there (who were all engineers) agreed it was a joke. >> >> "Hey! If I leave out the input protection circuitry, I can reduce the >> failure rate by 600 FITs! And if I get rid of one of these parallelled >> MOSFETs, I can save another hundred!" (Not.) >> >> Cheers >> >> Phil Hobbs > > Some of our customers want an MTBF calculation, based on the mil hbk > or Bellcore numbers, so we do it for them. Their quality people are > invariably lunatics so we do what we need to to keep them off our > case. DGMS on SPC.Quality people are invariably lunatics. If they were sane to begin with, the job drives them nuts very rapidly. (It's a bit like social workers--the ones who are actually sympathetic can't stand the job.) Part of the reason, I think, is that their only performance metric is adherence to arbitrary rules, like six-sigma, continuous improvement, and whatever the current version is of ISO-%$&#@@!!. Continuous improvement may be the stupidest of the lot--if you had one failure in the previous arbitrarily-chosen measurement period, God help you if you have two in this period. And God help you again if you ever have zero failures--because then you aren't allowed any more, ever.> > Most of our products have field failure rates far below the > calculations. When one doesn't, there's a reason. Like "it's heavy and > customers tend to drop it."Parts nowadays are very reliable if you don't mistreat them. 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 https://hobbs-eo.com
Reply by ●December 15, 20172017-12-15
Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> wrote:> On 12/15/2017 05:34 AM, Steve Wilson wrote:>> FIT is "Failure in Time" and is a reliability term. It is defined as a >> failure rate of 1 per billion hours. It obviously applies after the parts >> have already been accepted and placed in service.> And is used based on the now completely discredited reliability > estimation method of MIL-HDBK-217. The idea that the failure rate of a > system can be calculated as the sum of tabulated, invariant failure > rates of the individual parts is no better than a random number generator.John used the term, not me. It has nothing to do with AQL. Let's talk about AQL instead of FIT.> Cheers> Phil Hobbs
Reply by ●December 15, 20172017-12-15
On Fri, 15 Dec 2017 10:59:29 -0500, Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> wrote:>On 12/15/2017 10:33 AM, John Larkin wrote: >> On Fri, 15 Dec 2017 09:55:02 -0500, Phil Hobbs >> <pcdhSpamMeSenseless@electrooptical.net> wrote: >> >>> On 12/15/2017 05:34 AM, Steve Wilson wrote: >>> >>>> >>>> FIT is "Failure in Time" and is a reliability term. It is defined as a >>>> failure rate of 1 per billion hours. It obviously applies after the parts >>>> have already been accepted and placed in service. >>> >>> And is used based on the now completely discredited reliability >>> estimation method of MIL-HDBK-217. The idea that the failure rate of a >>> system can be calculated as the sum of tabulated, invariant failure >>> rates of the individual parts is no better than a random number generator. >>> >>> I had to use it back in the early '80s in my satellite radio job, but >>> even the managers there (who were all engineers) agreed it was a joke. >>> >>> "Hey! If I leave out the input protection circuitry, I can reduce the >>> failure rate by 600 FITs! And if I get rid of one of these parallelled >>> MOSFETs, I can save another hundred!" (Not.) >>> >>> Cheers >>> >>> Phil Hobbs >> >> Some of our customers want an MTBF calculation, based on the mil hbk >> or Bellcore numbers, so we do it for them. Their quality people are >> invariably lunatics so we do what we need to to keep them off our >> case. DGMS on SPC. > >Quality people are invariably lunatics. If they were sane to begin >with, the job drives them nuts very rapidly. (It's a bit like social >workers--the ones who are actually sympathetic can't stand the job.) > >Part of the reason, I think, is that their only performance metric is >adherence to arbitrary rules, like six-sigma, continuous improvement, >and whatever the current version is of ISO-%$&#@@!!. > >Continuous improvement may be the stupidest of the lot--if you had one >failure in the previous arbitrarily-chosen measurement period, God help >you if you have two in this period. And God help you again if you ever >have zero failures--because then you aren't allowed any more, ever.That's not a problem for us. A quality audit team shows up and I always ask them... Do you know what we make? Have you ever seen one? Do you know how many we ship? Do you know the field failure rate? Of course, all the answers are "no." All they care about is their cult rituals. But it seems as if some of their other vendors do have serious DOA and field failure rates. But the rituals won't help that.> >> >> Most of our products have field failure rates far below the >> calculations. When one doesn't, there's a reason. Like "it's heavy and >> customers tend to drop it." > >Parts nowadays are very reliable if you don't mistreat them.Yes. Incoming inspection is not reasonable (parts on reels, complex chips) or necessary. There is no way we'd do incoming testing on an 800-ball FPGA or a 250 MHz ADC. -- John Larkin Highland Technology, Inc picosecond timing precision measurement jlarkin att highlandtechnology dott com http://www.highlandtechnology.com
