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Eddy current sensing using AD5933

Question asked by Mikkie on Jun 3, 2015
Latest reply on Jun 4, 2015 by musach

Hello, I have an application where I need to measure the relative thickness of copper on a lead substrate. The copper thickness would typically be in the range of 1.5mm down to 0.35mm.

The plated object moves pass the sensor at a  fixed and controlled rate, with the sensor subsystem measuring the thickness of the copper at regular intervals, building a map indicating the difference in measured thickness. The absolute thickness is not of much concern, just the relative difference.

I thought it would be possible to make use of an eddy current sensor to measure this, since the u0 of the copper and lead is quite far apart. I was considering using a ferrite cored wire wound sensor, where the ferrite is either 0.7mm or 1.5mm with about 500 turns. We will wind the coils in-house for the testing, so can do basically any configuration required. The target is to keep the final coil diameter below 3mm.

Any ideas and suggestions on how to tackle this problem would be appreciated.

Best regards