Forums

Shock and Vibration specs of SD and Micro SD sockets ?

Started by Anton Erasmus February 12, 2007
Hi,

I have been looking at using either SD Flash or Micro SD Flash on a
system which logs a fair amount of data. However this system will be
mounted on a vehicle so it will see a certain amount of shock and
vibration. I have been searching for SD and Micro SD sockets, and have
found a few, but I have been unable to found a manufacturer that
actually lists information on what sort of shock and vibration levels
will start to cause problems with accessing the flash device.
Any pointers to such info would be greatly appreciated.

Regards
  Anton Erasmus
On Feb 12, 3:05 pm, Anton Erasmus <nob...@spam.prevent.net> wrote:
> Hi, > > I have been looking at using either SD Flash or Micro SD Flash on a > system which logs a fair amount of data. However this system will be > mounted on a vehicle so it will see a certain amount of shock and > vibration. I have been searching for SD and Micro SD sockets, and have > found a few, but I have been unable to found a manufacturer that > actually lists information on what sort of shock and vibration levels > will start to cause problems with accessing the flash device. > Any pointers to such info would be greatly appreciated.
Good luck on that one. I have worked off and on in defense for many years and I have seldom found vendors of low cost/high volume commercial components much interested in providing the sort of data required. You will likely have to do your own testing for this. One thing I would recommend is that you provide your own mechanical card retention. The rest of the connector is likely to work well as long as the case is sealed from the environment. Oh yeah, be sure to select a vendor that uses gold over nickle plating on the contacts. I assume you can find this in a low end commercial product. Otherwise you are likely to see premature failures.
rickman wrote:
> On Feb 12, 3:05 pm, Anton Erasmus <nob...@spam.prevent.net> wrote: > >>Hi, >> >>I have been looking at using either SD Flash or Micro SD Flash on a >>system which logs a fair amount of data. However this system will be >>mounted on a vehicle so it will see a certain amount of shock and >>vibration. I have been searching for SD and Micro SD sockets, and have >>found a few, but I have been unable to found a manufacturer that >>actually lists information on what sort of shock and vibration levels >>will start to cause problems with accessing the flash device. >>Any pointers to such info would be greatly appreciated. > > > Good luck on that one. I have worked off and on in defense for many > years and I have seldom found vendors of low cost/high volume > commercial components much interested in providing the sort of data > required. You will likely have to do your own testing for this. One > thing I would recommend is that you provide your own mechanical card > retention. The rest of the connector is likely to work well as long > as the case is sealed from the environment. > > Oh yeah, be sure to select a vendor that uses gold over nickle plating > on the contacts. I assume you can find this in a low end commercial > product. Otherwise you are likely to see premature failures. > > >
Sounds like a packaging problem. If the data logger is small enough, wrap it up in styraform and rubber shock mounts. Logomatic Serial SD Datalogger: http://www.sparkfun.com/commerce/product_info.php?products_id=752 donald
On Feb 12, 3:05 pm, Anton Erasmus <nob...@spam.prevent.net> wrote:

> found a few, but I have been unable to found a manufacturer that > actually lists information on what sort of shock and vibration levels > will start to cause problems with accessing the flash device.
That is at least partly because it is HEAVILY dependent on the mechanical design of your device. It's also slightly dependent on the orientation of the device. The SD family of devices have relatively low mass and the connectors have a fairly high contact force. Use push-pull connectors by preference (push-push may self-eject accidentally), and provide an external mechanical lock to prevent the card from sliding out.This need not be anything more complicated than a screw running through the PCB.
On 12 Feb 2007 19:06:35 -0800, "larwe" <zwsdotcom@gmail.com> wrote:

>On Feb 12, 3:05 pm, Anton Erasmus <nob...@spam.prevent.net> wrote: > >> found a few, but I have been unable to found a manufacturer that >> actually lists information on what sort of shock and vibration levels >> will start to cause problems with accessing the flash device. > >That is at least partly because it is HEAVILY dependent on the >mechanical design of your device. It's also slightly dependent on the >orientation of the device. > >The SD family of devices have relatively low mass and the connectors >have a fairly high contact force. Use push-pull connectors by >preference (push-push may self-eject accidentally), and provide an >external mechanical lock to prevent the card from sliding out.This >need not be anything more complicated than a screw running through the >PCB.
I realise this, but was hoping to get either some figures, or experience from others. What sort of filtering do the actual SD Flash devices provide on their inputs ? Would the lower speed devices be more noise immune ? i.e. Less likely to "see" a glitch caused by a connect-disconnect-connect sequence caused by a shock ? I have been searching to find vendors where one can easily buy these sockets in low quantities. So far I have found only RS-Componets where one can buy one-off without problems. Regards Anton Erasmus
On Feb 13, 2:38 pm, Anton Erasmus <nob...@spam.prevent.net> wrote:
> On 12 Feb 2007 19:06:35 -0800, "larwe" <zwsdot...@gmail.com> wrote: > > > > > > >On Feb 12, 3:05 pm, Anton Erasmus <nob...@spam.prevent.net> wrote: > > >> found a few, but I have been unable to found a manufacturer that > >> actually lists information on what sort of shock and vibration levels > >> will start to cause problems with accessing the flash device. > > >That is at least partly because it is HEAVILY dependent on the > >mechanical design of your device. It's also slightly dependent on the > >orientation of the device. > > >The SD family of devices have relatively low mass and the connectors > >have a fairly high contact force. Use push-pull connectors by > >preference (push-push may self-eject accidentally), and provide an > >external mechanical lock to prevent the card from sliding out.This > >need not be anything more complicated than a screw running through the > >PCB. > > I realise this, but was hoping to get either some figures, or > experience from others. What sort of filtering do the actual SD > Flash devices provide on their inputs ? Would the lower speed devices > be more noise immune ? i.e. Less likely to "see" a glitch caused by a > connect-disconnect-connect sequence caused by a shock ? > > I have been searching to find vendors where one can easily buy these > sockets in low quantities. So far I have found only RS-Componets where > one can buy one-off without problems.
I found some data at Digikey. They sell at least three brands, 3M, AVX and Molex. The Molex data sheet shows vibration and shock data... This will not format here, but you get the idea... 4 Vibration Mate dummy card and subject to the following vibration conditions, for a period of 2 hours in each of 3 mutually perpendicular axis, passing DC 1mA during the test. Amplitude: 1.5mm P-P or 49m/s2 Frequency: 10-55-10 Hz Shall be traversed in 20 minute. (EIA 364-28 Condition 1) Appearance: No damage. Contact resistance: 80m MAX. Discontinuity: 100 Nanosecond max. 5 Shock (Mechanical) Mate a dummy card and subject to the following shock conditions. 3 shocks shall be applied along 3 mutually perpendicular axis, passing DC 1 mA current during the test. (Total of 18 shocks) Test pulse: Half Sine Peak value: 980 m/s2 {100G} Duration: 6 millisecond (EIA 364-27 Condition C) Appearance: No damage. Contact resistance: 80m MAX. Discontinuity: 0.1 microsecond MAX. They do seem to allow for 100 ns of disconnection on the contacts. That could be significant if you are operating at the time. I searched on SD Card and then weeded out irrelevant stuff.
On 13 Feb 2007 12:14:44 -0800, "rickman" <gnuarm@gmail.com> wrote:

>On Feb 13, 2:38 pm, Anton Erasmus <nob...@spam.prevent.net> wrote: >> On 12 Feb 2007 19:06:35 -0800, "larwe" <zwsdot...@gmail.com> wrote: >> >> >> >> >> >> >On Feb 12, 3:05 pm, Anton Erasmus <nob...@spam.prevent.net> wrote: >> >> >> found a few, but I have been unable to found a manufacturer that >> >> actually lists information on what sort of shock and vibration levels >> >> will start to cause problems with accessing the flash device. >> >> >That is at least partly because it is HEAVILY dependent on the >> >mechanical design of your device. It's also slightly dependent on the >> >orientation of the device. >> >> >The SD family of devices have relatively low mass and the connectors >> >have a fairly high contact force. Use push-pull connectors by >> >preference (push-push may self-eject accidentally), and provide an >> >external mechanical lock to prevent the card from sliding out.This >> >need not be anything more complicated than a screw running through the >> >PCB. >> >> I realise this, but was hoping to get either some figures, or >> experience from others. What sort of filtering do the actual SD >> Flash devices provide on their inputs ? Would the lower speed devices >> be more noise immune ? i.e. Less likely to "see" a glitch caused by a >> connect-disconnect-connect sequence caused by a shock ? >> >> I have been searching to find vendors where one can easily buy these >> sockets in low quantities. So far I have found only RS-Componets where >> one can buy one-off without problems. > >I found some data at Digikey. They sell at least three brands, 3M, >AVX and Molex. The Molex data sheet shows vibration and shock data... >
[Snipped] Thanks, I found only one Micro SD connector on Digikeys site. (3M). The vibration stuff from Molex is for Mini SD. I did find Micro SD connectors on Molex's own site, but the only data I could get on these were mechanical drawings. Since the Micro SD is quite a bit smaller and lighter than the Mini SD, I would expect at worst the same results as the Mini SD, and probably better. It looks like one would be able to use these smaller flash cards in quite harsh environments - shock and vibration wise. Regards Anton Erasmus
On Feb 14, 2:22 pm, Anton Erasmus <nob...@spam.prevent.net> wrote:
> On 13 Feb 2007 12:14:44 -0800, "rickman" <gnu...@gmail.com> wrote: > > > > > > >On Feb 13, 2:38 pm, Anton Erasmus <nob...@spam.prevent.net> wrote: > >> On 12 Feb 2007 19:06:35 -0800, "larwe" <zwsdot...@gmail.com> wrote: > > >> >On Feb 12, 3:05 pm, Anton Erasmus <nob...@spam.prevent.net> wrote: > > >> >> found a few, but I have been unable to found a manufacturer that > >> >> actually lists information on what sort of shock and vibration levels > >> >> will start to cause problems with accessing the flash device. > > >> >That is at least partly because it is HEAVILY dependent on the > >> >mechanical design of your device. It's also slightly dependent on the > >> >orientation of the device. > > >> >The SD family of devices have relatively low mass and the connectors > >> >have a fairly high contact force. Use push-pull connectors by > >> >preference (push-push may self-eject accidentally), and provide an > >> >external mechanical lock to prevent the card from sliding out.This > >> >need not be anything more complicated than a screw running through the > >> >PCB. > > >> I realise this, but was hoping to get either some figures, or > >> experience from others. What sort of filtering do the actual SD > >> Flash devices provide on their inputs ? Would the lower speed devices > >> be more noise immune ? i.e. Less likely to "see" a glitch caused by a > >> connect-disconnect-connect sequence caused by a shock ? > > >> I have been searching to find vendors where one can easily buy these > >> sockets in low quantities. So far I have found only RS-Componets where > >> one can buy one-off without problems. > > >I found some data at Digikey. They sell at least three brands, 3M, > >AVX and Molex. The Molex data sheet shows vibration and shock data... > > [Snipped] > > Thanks, > > I found only one Micro SD connector on Digikeys site. (3M). The > vibration stuff from Molex is for Mini SD. I did find Micro SD > connectors on Molex's own site, but the only data I could get on these > were mechanical drawings. Since the Micro SD is quite a bit smaller > and lighter than the Mini SD, I would expect at worst the same results > as the Mini SD, and probably better. It looks like one would be able > to use these smaller flash cards in quite harsh environments - shock > and vibration wise.
I find it odd that they spec a 100 nanosecond disconnect time during the test. Will your application tolerate such a disconnection? You might be able to get the specs you need if you contact the manufacturers. They often have done various testing, but only make the results available on request.