Steve,
If I might offer my opinion, well some fact
too...
An issue with XRF and trace thickness...the density
of the copper being measured, while you can standardize the xray with your basic
core/foil materials trying to duplicate the density of the plated copper will
often throw off the count, making for erroneous readings...if you standardize
your xray daily you've set it up against perhaps your copper standard, the
copper foil but what is not known is the density of the plated
copper.
Some say copper is going to remain a certain
density regardless of how it was formed...and thats not true...grain structure,
contaminates, chemistry imbalance, air...looking at the bath the wrong way...all
may affect this...and thus your readings...
The xray is very useful as a process control tool,
veryifying from lot to lot on known (standardized) raw material types. What I
like to do is verify the xray data with a cross-sectioned measured sample for
correlation...together they can really tell a lot about the
process...
For greater accuracy in determining actual
thickness, of course, microsection is the way to go...
Franklin
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