Eddy current measurements of thin-film metal coatings using a selectable calibration standard
US6549006B2 · kind B2 · utility
Inventor
Key dates
| Filing date | Apr 17, 2001 |
| Grant date | Apr 15, 2003 |
| Priority date | — |
| Expiry date | Apr 17, 2021 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01B7/105
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A method for identifying metal layer thickness of an inspection sample according to one embodiment utilizes an eddy current probe to obtain initial resistance and reactance measurements from the inspection sample. Once these measurements have been obtained, the relative distance between the eddy current probe and inspection sample is increased and terminating resistance and reactance measurements are obtained. An inspection sample intersecting line may then be calculated using the initial and terminating resistance and reactance measurements. An intersecting point between a natural intercepting curve and the inspection sample intersecting line may also be determined. A reactance voltage of the intersecting point along a digital calibration curve is calculated to identify a closest two of a plurality of calibration samples. The metal layer thickness of the inspection sample may then be calculated by performing an interpolation between the identified closest two calibration samples.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.