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Shock and Vibration specs of SD and Micro SD sockets ?

Discussion in 'Embedded' started by Anton Erasmus, Feb 12, 2007.

  1. 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
     
    Anton Erasmus, Feb 12, 2007
    #1
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  2. Anton Erasmus

    rickman Guest

    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, Feb 12, 2007
    #2
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  3. Anton Erasmus

    Donald Guest

    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
     
    Donald, Feb 13, 2007
    #3
  4. Anton Erasmus

    larwe Guest

    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.
     
    larwe, Feb 13, 2007
    #4
  5. 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
     
    Anton Erasmus, Feb 13, 2007
    #5
  6. Anton Erasmus

    rickman Guest

    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.
     
    rickman, Feb 13, 2007
    #6
  7. [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
     
    Anton Erasmus, Feb 14, 2007
    #7
  8. Anton Erasmus

    rickman Guest

    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.
     
    rickman, Feb 16, 2007
    #8
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