Ed,

a wild guess:

Is your board gold plated? Under the gold there is usually nickel which
will influence any eddy current measuring (such as CMI or FISCHER).

Hole and board thickness also plays a role...

Jens




>Hi all,
>
>Just a question. I have been having problems getting my CMI unit to read
copper thickness consistently. It has typically been reading low. For
instance, the meter will show .0005 to .0006 of copper on a standard .042
thru hole but a section of the same hole shows .0012.  The meter reads fine
to the provided standard.  Has anyone else experienced this problem. I
should note that the meter was just calibrated a few weeks ago so
calibration should not be an issue.
>
>Ed Cosper

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