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Best method to test copper thickness

We have been plating a brass part with matte tin and copper undercoat. Our customer had been rejecting us on the thickness of copper (2-3 microns). They had been doing a cross sectioning to measure the thickness under magnification. My plater only has an x-ray testing machine and it is not possible to check the thickness of copper with a brass base. They had been substituting the brass with mild steel for testing purpose only. Is the thickness of copper on mild steel and brass the same if it is plated in the same barrel? What is the most suitable method to check these parts? What is the function of brass undercoat and is the function very critical (the customer claims our thickness is about 1.8 microns with uneven thickness along the diameter)?

Padmavathy Subbrayan
- Penang, Malaysia

If the brass is more conductive than mild steel, it would plate faster in the same barrel. Also if the steel part is a different size than your brass part, that would change the plating rate as well. Careful cross section I believe is your best and only method to determine your copper thickness.

Karl Weyermann
- Lebanon, Kentucky

Your application can be measured with newer x-ray instruments and in fact many older models that have a nickel filter should also work for your application.

Christian Petrilli
Fischer Technology, Inc. - Windsor, Connecticut