Application of nondestructive testing methods to electronic industry using computer-aided optical metrology

Abstract

A novel application of NDT to the electronic industry using computer-aided optical metrology that includes Electronic Speckle Pattern Interferometer (ESPI), Electronic Shearing Speckle Pattern Interferometer (ESSPI) and Digital Speckle Correlation Method (DSCM) was described. The theoretical analysis based on interferometry and the deformation theory was presented and the relationship between fringe-distribution and defect-geometry was given. An important technique—computer-controlled polarization phase shifting—was developed for improving the fringe quality and the sensitivity of ESPI and ESSPI. In order to improve the sensitivity for NDT of small object like electronic elements, a new NDT method using DSCM was first introduced. Two key techniques, the cross-search algorithm and double-lens optical arrangement, were developed to provide the possibility of high processing speed and small object measurement. These new techniques will make DSCM the most powerful NDT tool in electronic engineering. Several applications are presented as examples in this paper; they include the electrosound elements, miniaturized multilayer ceramic capacitor (MLC), compact disk (CD) and optical fibers. The findings have demonstrated that computer-aided optical metrology is a powerful tool for NDT applications in electronic engineering.