Steve,
I'm curious: what voltage was applied across VCC-ground and for how long?

Timothy Reeves
ECD Circuit Board Division
13626 South Freeman Road
Mulino, OR 97042
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(503) 829-9108 (800) 228-8198  FAX (503) 829-5482


> ----------
> From:         Stephen R. Gregory
> Sent:         Tuesday, February 29, 2000 7:33
> Subject:      Was; Electromigration Now; Electrochemical Migration
>
> 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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