Paul

This sounds like a bastardised Jennings test. This is usually done under
a microscope and visual formation of dendrites observed. I, personally,
have never heard of a current gradient being specified, but that
probably does not mean anything. I would seriously question the value of
the water resistivity, though. The idea is to provoke dendrites from
ionic surface contamination, not from ions that may be in the water. I
would seriously suggest that your water should have a resistivity of at
least 10 Mohms-cm (conductivity <0.1 uS-cm) for the test to be
meaningful.

There is no reason for the test not to be applied, by sampling, as a
process control test.

Brian

tech wrote:
>
> We're being asked to perform  electro migration testing on an ongoing
> basis on pcbs we produce. The test required is defined as follows:
> A drop of water (.5 Megohms/cm.) is dropped between 2 traces spaced .010
> apart and a current of 3V DC is applied. Current leakage of no more than
> 30 micro amps / thou of seperation /minute must be met ???
>  Is this a "standard" test and if so is a procedure defined anywhere (
> IPC , MIL. etc) ?  Is it typical to perform this as a routine QC check
> or is it the type of test normally performed as a qualification  test
> only ?
>  Any information on this would be much appreciated.
> Paul Greene
>
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