Steve:  We have watched electrochemical migration.  We use a procedure:
*  Based on IPC-TM-650, 2.6.13, which is possibly what Gaby was referring to in her
comments.
*  Developed by folks at Wavetek with help from Joe Keller.
*  Outlined in "EP&P" magazine, 10/99, p 45.

We are not concerned about color.  We are not even concerned about seeing the growth.
We are more concerned about current flow, because:
*  Some growths "disappear" when the current reaches a certain level.
*  Some people "see" growths, some people don't.  And some of those that see them see
them in different places ...

A Fluke sampling and recording current is nice.  With that you can watch.  But color is
tough to define.  Our lighting is not great either.

Dave Fish

"Stephen R. Gregory" wrote:

> Hi ya'll!
>
> After all the replies that were sent to me, I think what I have is
> electrochemical migration. I wish I had a microscope where I could take a
> picture to show you, but I'll describe things again.
>
> There is a 6-pin header that is hand-soldered on this board. The board failed
> due to a short from VCC to Ground. We removed the header to see if we could
> spot anything beneath the plastic of the header because we didn't see
> anything on the other side of the board. This header location has traces that
> run between some of the pins, and what I discovered that is if the mask isn't
> perfectly registered, the clearance area around each of the holes for the
> header will expose an area on the traces that are running between them.
>
> On one of the boards that I looked at yesterday, I observed a "fern-like"
> stucture of copper that appeared to be growing from the anular pad of the
> header pins to the exposed area of the trace. I seen this at two places at
> the header locations...
>
> I also discovered (to my dismay) that one or two of the operators have just
> been hand cleaning after soldering in this header. That since has ceased
> (dammit!)...
>
> Again, I just want to ask, has anybody else ever seen actual copper filaments
> grow like that? From the replies I got back yesterday, most were telling me
> that I should be seeing a black, or maybe greenish mess there, and that it
> would be really tough to tell if it was copper. But I swear, it clearly has a
> copper color to it..
>
> Thanks again!
>
> -Steve Gregory-
>
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