Abstract
As an anti-counterfeiting aid, a thin, clear, ultraviolet-cured coating, invisible to the eye, is applied to electronic components as a taggant. It is detected via diffuse reflection near infrared (DR-NIR) spectroscopy. This paper describes the potential difficulties of measuring extremely thin layers of organic materials on a highly-scattering matrix. Principal component analysis (PCA) was a useful tool with which to examine the loadings and residual variance plots for physical and chemical differences between coated and uncoated microchips. The various coating layer(s) differed only in the amount applied and, while spectrally difficult to quantify, were easily discriminated when plotting the principal component (PC) scores that described the major log 1/R regions of the thin film.
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