Automated visual inspection for IC wire-bond using auto-focusing technique

Abstract

An automated integrated circuit (IC) wire-bond inspection system has been successfully developed. The system is capable of measuring the height and diameter of the bonds. The bond height is detected by automatically computing the focused planes of the top and the base of the bond with a series of two-dimensional images of the bond. The focused plane of an image is obtained by extracting the high-frequency features of the image. By scanning horizontally and vertically for a steep change in gray level of the image, the diameter of the bond is calculated. The system carries out the measurement task at a speed of six bonds per minute. Precision of /spl plusmn/0.9 /spl mu/m and /spl plusmn/2.0 /spl mu/m for the height and diameter measurement can be obtained.<>