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Oxidisation of Seagate & WDC PCBs

Discussion in 'Electronic Repair' started by Franc Zabkar, Apr 8, 2010.

  1. Franc Zabkar

    Franc Zabkar Guest

    I came across a reference to this Russian forum thread in a WDC forum:
    http://maccentre.ru/board/viewtopic.php?t=70953&start=15

    Here is Google's translator:
    http://translate.google.com/translate_t?sl=ru&tl=en

    The thread discusses oxidisation of contact pads in current Seagate
    and Western Digital hard drives. The drives were used in typical
    office and home environments, and are about a year old. The thread has
    several detailed photos. All except the older tinned PCB appear to
    show evidence of serious corrosion.

    Is this the fallout from RoHS? Surely it's not the result of some cost
    saving measure?

    - Franc Zabkar
     
  2. Arno

    Arno Guest

    The silver ones are not oxydized. Silver reacts with sulphur,
    not oxygen. It is normal and cannot really prevented. It is
    also not a problem in contacts that are not used, as the
    process stops itselft after at thin coating is reached.

    The golden ones look like the same thing to me. Maybe the
    used a high silver content gold here. Sorry, I am noch a
    chemist. But my parents used to deal in silver jewelery
    and the look is characteristic.

    I suspect air pollution as the root cause. As I said, it is
    not a problem in this case, the sulphurisarion (?) process
    will not eat through the traces. They are rather better
    protected with this.

    It would be a problem on the connectors though. But they will
    have better and thicker gold anyways.

    Arno
     
  3. Arno

    Arno Guest

    No need.

    Arno
     
  4. Franc Zabkar

    Franc Zabkar Guest

    It's not just Russia that has this problem. The same issue comes up
    frequently at the HDD Guru forums.

    - Franc Zabkar
     
  5. Franc Zabkar

    Franc Zabkar Guest

    One of the sticky threads at the HDD Guru forums recommends that the
    preamp contacts on WD drives be scrubbed clean with a soft white
    pencil eraser whenever they come in for data recovery.

    - Franc Zabkar
     
  6. I'm right here in the US and I had 3 of 3 WD 1TB drives failed at the same
    time in RAID1 thus making the entire array dead. It is not that you can
    simply buff that dark stuff off and you're good to go. Drive itself tries to
    recover from failures by rewriting service info (remapping etc.) but
    connection is unreliable and it trashes the entire disk beyound repair. Then
    you have that infamous "click of death"... BTW, it is not just WD; others
    are also that bad.

    They had good old gold plated male/female headers on older drives and those
    were reliable. Newer drives had, sorry for an expression, "gold plated" pads
    and springy contacts from the drive heads. That would have them something
    like $0.001 saving per drive wrt those headers and they took that road. Gold
    plating was also of a cheapest variety possible, probably immersion so it
    wouldn't last long. Newest drives from Seagate also have that construction
    but pads look like tin plated, no gold. Don't know how long it would last.

    What we are looking at is an example of a brilliant design with a touch of
    genius--it DOES last long enough so they work past their warranty period and
    at the same time it will NOT last enough to make it work very long past the
    manucturer's warranty. I don't know if it is just greed/incompetence or a
    deliberate design feature but if it is the latter my kudos to their
    engineers for job well done :(
     
  7. Arno

    Arno Guest

    That sounds like BS to me. A soft pencil eraser cannot remove silver
    sulfide, it is quite resilient. There are special silver cleaning
    cloths that will do the trick.

    Still, I doubt that this is a problem. It shoud not crawl between
    working contacts, only unused ones.

    Arno
     
  8. Arno

    Arno Guest

    It is extremly unlikely for a slow chemical process to achive this
    level of syncronicity. About as unlikely that it would be fair to call
    it impossible

    Your array died from a different cause that would affect all drives
    simultaneously, such as a power spike.
    Tin lasts pretty long, unless you unplug/replug connectors. That is its
    primary weakness.
    I think you are on the wrong trail here. Contact mechanics and
    chemistry is well understood and has been studied longer than modern
    electronics. So has metal plating technology in general.

    Arno
     
  9. Arno

    Arno Guest

    I think people are jumping to conclusion, because the discolorarion
    is what they can see (and think they understand). There is a posting
    in this thread with a person that has had a 3-way RAID1 fail and
    attributes it to the contact discoloration. Now, whith a slow chemical
    process, the required level of synchronicity is as unlikely that
    calling it impossible is fair.
    Actually pure silver also sulfidizes (?) in this way. The
    look is very characteristic. I think this is silver plating
    we see. It is typically not a problem on contacts that
    are in use, it does not crawl between contact points.

    I suspect in the observed instances, this is a purely
    aestetic problem and has no impact on HDD performance
    or reliability whatsoever.

    Arno
     
  10. Yes, they did not die from contacts oxidation at that very same moment. I
    can not even tell they all died the same month--that array might've been
    running in degraded mode with one drive dead, then after some time second
    drive died but it was still running on one remaining drive. And only when
    the last one crossed the Styx the entire array went dead. I don't use
    Windows so my machines are never turned off unless there is a real need for
    this. And they are rarely updated once they are up and running so there is
    no reboots. Typical uptime is more than a year.

    I don't know though how I could miss a degradation alert if there was any.

    All 3 drives in the array simply failed to start after reboot. There were
    some media errors reported before reboot but all drives somehow worked. Then
    the system got rebooted and all 3 drives failed with the same "click of
    death."

    The mechanism here is not that oxidation itself killed the drives. It never
    happens that way. It was a main cause of a failure, but drives actually
    performed suicide like body immune system kills that body when overreacting
    to some kind of hemorrargic fever or so.

    The probable sequence is something like this:

    - Drives run for a long time with majority of the files never
    accessed so it doesn't matter if that part of the disk where they
    are stored is bad or not

    - When the system is rebooted RAID array assembly is performed

    - While this assembly is being performed a number of sectors on a
    drive found to be defective and drive tries to remap them

    - Such action involves rewriting service information

    - Read/write operations are unreliable because of failing head
    contacts so the service areas become filled with garbage

    - Once the vital service information is damaged the drive is
    essentially dead because its controller can not read vital data to
    even start the disk

    - The only hope for the controller to recover is to repeat the read
    in hope that it might somehow get read. This is that infamous
    "click of death" sound when drive tries to read the info again and
    again. There is no way it can recover because that data are
    trashed.

    - Drives do NOT fail while they run, the failure happens on the next
    reboot. The damage that would kill the drives on that reboot
    happened way before that reboot though.

    That suicide also can happen when some old file that was not accessed for
    ages is read. That attempt triggers the suicide chain.
     
  11. It's a technique that has been used on edge connectors for many years.
     
  12. JW

    JW Guest

    Yup, and it works. I learned the technique when servicing Multibus I
    systems, and still use it to this day.
     
  13. Arno

    Arno Guest

    Ah, I see. I did misunderstand that. May still be something
    else but the contacts are a possible explanation with that.
    So your disks worked and then refused to restart? Or you are running
    a RAID1 without monitoring?
    Well, if it is Linux with mdadm, it only sends one email per
    degradation event in the default settings.
    I run long smart selftest on all my drives (RAID or no) every
    14 days to prevent that. Works well.
    Yes, that makes sense. However you should do surface scans on
    RAIDed disks regularly, e.g. by long SMART selftests. This will
    catch weak sectors early and other degradation as well.

    Arno
     
  14. Arno

    Arno Guest

    For high reliability requirements it is also a good idea to use
    different brand drives, to get a better distributed times between
    failures. Some people have reported the effect you see.

    A second thing that can cause this effect is when the disks are not
    regularly surface scanned. I run a long SMART selftest on all disks,
    also the RAIDed ones for this every 14 days. The remaining disks are
    under more stress during array rebuild, especially if the have weak
    sectors. This additional load can cause the remaining drives to
    fail a lot faster, in the wort case during array rebuild.

    Arno
     
  15. Arno

    Arno Guest

     
  16. I don't think it is something else but everything is possible...
    They failed during weekly full backup. One of the files read failed and they
    entered that infinite loop of restarting themself and retrying. Root
    filesystem was also on that RAID1 array so there was no other choice than
    to reboot. And on that reboot all 3 drives failed to start with the same
    "click of death" syndrome.
    Yep, I probably missed it when shoveling through mountains of spam.
    I know but I simply didn't think all 3 drives can fail... I thought I have
    enough redundancy because I put not 2 but 3 drives in that RAID1... And I
    did have something like a test with regular weekly full backup that reads
    all the files (not the entire disk media but at least all the files on it)
    and that was that backup that triggered disk suicide.

    Anyway lesson learned and I'm taking additional measures now. It was not a
    very good experience loosing some of my work...

    BTW, I took a look at brand new WDC WD5000YS-01MPB1 drives, right out of the
    sealed bags with silica gel and all 4 of those had their contacts already
    oxidized with a lot of black stuff. That makes me very suspicious that
    conspiracy theory might be not all that crazy--that oxidation seems to be
    pre-applied by the manufacturer.
     
  17. Rod Speed

    Rod Speed Guest

    MUCH more likely that someone fucked up in the factory.
     
  18. Arno

    Arno Guest

    Yes, I can imagine. I have my critical stuff also on a 3 way RAID1,
    but with long SMART selftests every 2 weeks and 3 different drives,
    two from WD and one from Samsung. One additional advantage of the
    long SMART selftest is that with smartd you will get a warning
    email on every failing test, i.e. one every two weeks. For additional
    warning you can also run a daily short test, e.g..
    Urgh. These bags are airtight. No way the problem happened on your
    side then. My two weeks old WD5000AADS-00S9B0 looks fine on the top
    of the PCB. I think I will have a look underneath later.

    Arno
     
  19. No matter what you do you can not prevent an occasional disaster :( One
    MUST remember that "backup" in not a noun but a verb in imperative.
    Those 4 were fine on the top of PCB. Black stuff was underneath, on those
    pads contacting with springy heads pins.
     
  20. Arno

    Arno Guest

    Mine is fine on both sides. However there is a quite a bit of contact
    area that looks and feels silver-plated to me, most notably areound
    the screws and on the bottom the contacts to the head assembly.

    Arno
     
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