A Calibration Technique for Measuring Nickel Plating Thickness

Abstract

A calibration technique was developed to predict nickel plating thickness of a manufactured part. The technique was used to replace a destructive scanning electron microscope (SEM) measurement, with a nondestructive X-ray fluorescence (XRF) measurement. The XRF measurement was used to screen suspect parts from a rejected lot, and to replace lot-by-lot sampling with screening for ongoing product acceptance. The key to this approach was calibration and quantification of prediction uncertainty. Guardbanding, based on prediction uncertainty, was used to minimize the probability of accepting defective product. A significant number of suspect parts from a rejected lot were screened and deemed acceptable for use in next assembly with minimal risk.