Dear Colleagues,

I am writing with respect to a 4 layer (mixed technology) PCB with the
following layering:

Component side traces
Ground plane
Vcc plane
Solder side traces.

We have, on three occasion, had boards burn out after the boards were in
service for some time. The burns are between the 12V battery traces and
other traces/planes. The 12V is fused with a 1.5V quick fuse. The post
mortem on one occasion indicated that the short occurred between a component
pin and the ground plane. The other cases are not so clear as the short
occurred on an inside layer along an edge of the board. The spacing
generally is 0.015".

I recall to have read in the past about wisker growth. Can anyone point me
to such literature, preferably in EDN, Electronic Design. Any help would be
appreciated.


Rolf Ehrat, Sen. Des. Eng.		Tel. (905) 669-2280 ext. 320
Scintrex Ltd.				FAX  (905) 669-5132
222 Snidercroft Rd.
Concord, Ont.
L4K 1B5

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