Metal crystal 'whisker' growth!

Discussion in 'Off-Topic' started by rjenkins, May 31, 2010.

  1. rjenkins

    Thread Starter AAC Fanatic!

    Nov 6, 2005
    1,015
    69
    Hi,
    I've had a dead Netgear ethernet switch kicking about for a while, and just decided to try and fix it.

    I took the cover off and found what initially looked to be something like mould, but on close examination it's crystalline growth from the inside of the cover.

    I did a quick bit of research and found a section of the NASA site dedicated to this phenomena, with lots of other info and photos, here:
    http://nepp.nasa.gov/whisker/index.html

    A couple of my photos are attached.

    Weird, huh?

    Robert.

    [​IMG]

    [​IMG]
     
  2. VoodooMojo

    Active Member

    Nov 28, 2009
    503
    53
    what a fantastic example of that!

    We have had a few issues with this since the removal of lead from the solder.

    The shocker of all this is that any one of those little whiskers can carry a whopping 30 milliamps of current!
     
  3. R!f@@

    AAC Fanatic!

    Apr 2, 2009
    8,754
    760
    EEEEEEEp!! what the heck is that? :eek:
    15 years, I taken cover of almost everything but never seen 'em
     
  4. BMorse

    Senior Member

    Sep 26, 2009
    2,675
    234
    what is the cover made of to where it is growing those "whiskers"?? I don't think it is made up of any of the materials that "grow" these whiskers....

    B. Morse
     
  5. beenthere

    Retired Moderator

    Apr 20, 2004
    15,815
    282
    Looking at the crud, I wonder if there isn't a coin cell battery under all that.
     
  6. jpanhalt

    AAC Fanatic!

    Jan 18, 2008
    5,699
    905
    I am plumb sure I will never switch to lead-free solder.

    John
     
  7. R!f@@

    AAC Fanatic!

    Apr 2, 2009
    8,754
    760
    does Lead prevent. that **** from formin?
     
  8. Markd77

    Senior Member

    Sep 7, 2009
    2,803
    594
    Apparently so. I've got some good deals on non ROHS stuff recently that suppliers are trying to get rid of. Best so far was 7 segment leds for 11p each.
     
  9. Ghar

    Active Member

    Mar 8, 2010
    655
    72
    I really don't think those are tin whiskers...

    Is there any comparable photo on the NASA site? I haven't seen anything approaching this.

    There's probably more of this fluff than you have tin in the entire assembly which doesn't make any sense.
     
  10. beenthere

    Retired Moderator

    Apr 20, 2004
    15,815
    282
    Think battery that got discharged to death.
     
  11. BMorse

    Senior Member

    Sep 26, 2009
    2,675
    234
    I do not see a battery anywhere, (and I do not believe Netgear devices have any type of battery backup/ coin cell battery), but it does look like it all emanated from the power supply board, it seems to have started right where the AC comes in (must have been a huge glob of tin solder there), what is that device above the cap? Is the cap still intact?

    B. Morse
     
  12. rjenkins

    Thread Starter AAC Fanatic!

    Nov 6, 2005
    1,015
    69
    The 'growth' is coming down from the inside of the lid, not growing upwards.
    The sheet metal of the lid is presumably galvanised steel, so the crystals will be Zinc, not Tin.

    The switch was fitted in a wall mounted network cabinet in an office building file room. It had vents but no fans anywhere & I think this helped the spot heating of the lid and prevented the 'growth' being distrurbed.

    I sent some of the pics to the guys at Nasa & have had a reply back from them.

    They agree it could be Zinc crystal growth and would like to examine it under a scanning electron microscope, so it'd going off to Goddard space center to be added to their collection - assuming they determine that it is actually a form of metal whisker growth.

    Re. the electrical damage, it appears the filter inductor at the AC input to the power supply has cooked, the windings look partly blackened rather than being an even enameled copper colour. That's the black lump at the top right of the circuit board.

    The capacitor and all other components look to be intact, I don't think the 'growth' got past the filter stages on the PSU board. There is possibly an AC fuse under the crud, but I don't want to disturb it to find out.
     
    Last edited: Jun 1, 2010
  13. mcgyvr

    AAC Fanatic!

    Oct 15, 2009
    4,771
    971
    That is not tin whiskers... Really looks like battery acid crystals or maybe someting leaking from the capacitors...
     
  14. t06afre

    AAC Fanatic!

    May 11, 2009
    5,939
    1,222
    From the pictures it does not look like metal to me. If it had been metal. I think you would have seen some holes in chassis sheet work. Al that stuff have to come from somewhere. But I have been wrong before ;)
     
  15. retched

    AAC Fanatic!

    Dec 5, 2009
    5,201
    312
    I have seen something like this once before. During my HVAC career, I came across a boiler that was not functioning, I opened the control case to quite the same look.

    And we were talking about this earlier in the week..

    Do you have a cat?

    Cat urine and the warmth of the cap filter stage likes to grow "fur". I do not recall if the structures were as crystalline. But it will be interesting to find out what the result is.
     
  16. rjenkins

    Thread Starter AAC Fanatic!

    Nov 6, 2005
    1,015
    69
    No batteries in it & no Cat!
    It was screwed in to the wallbox from new and only removed when it failed recently.

    The 'fur' in the main body of the unit is what's broken away from the growth source on the lid when I opened the case.
     
Loading...