Tuesday, March 22, 2011

Whiskers


 The other day we pulled a module out of one of our test stations and we saw some curious whiskers growing on it. That isn't a real problem by itself except that the whiskers were growing between two electrical contacts and if they actually connected the two contacts they could short out our module. We came up with a working theory on what could be causing the whiskers but to confirm our theory we had to confirm exactly what the whiskers were made of. The easiest way to do that was to take the module to a scanning electron microscope (SEM for short).


For those of you who don't know what an electron microscope let me explain it to you. When you  look through a normal optical microscope you can magnify objects up to about 800 times. If you try and magnify higher than that they you are trying to see objects that are shorter than the wavelength of light. If you're smaller than light then obviously light can't see you. An electron microscope shoots an electron beam at the object and that means you can then see object that are as small as the electrons are. Since electrons are much smaller than atoms are that means you can actually see atoms with an electron microscope. That is pretty small. 




The cool thing is that when you fire an electron at an object then the electron energizes the electrons in the atoms and then when the energized electrons fall back to their normal orbitals they give of x-rays. From the energy of the x-ray you can tell what atom it was. Most SEM's have an x-ray detector in them that will tell you the composition of the material you're looking at. It turns out that these whiskers are pure copper. That is not what we were expecting. Now we have to come up with a new theory.


While we're not happy to find whiskers on our module they are pretty cool looking. I thought I'd share some of them with you.




















----------trivia----------
After reexamining data taken from soil samples of its 1976 Viking mission, NASA determined that its probes did in fact locate organic compounds on Mars indicating that there is indeed life on Mars.
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3 comments:

Lisa said...

Bizarre, that's never happened before has it? The pictures are pretty cool and I know you like using that microscope.

Brandon J. Leavitt said...

https://docs.google.com/viewer?url=http%3A%2F%2Fwww2.dupont.com%2FImaging_Materials%2Fen_US%2Fassets%2Fdownloads%2Ftechtalk%2FTT0307.pdf

I suggest you clean the shop.

Alycia (Crowley Party) said...

These are beautiful. You could hang this up and call it art :)