A vision system for inspection of ball bonds in integrated circuits

The paper describes a vision system for automatic inspection of the connecting part of the wire bond of an IC where the wire connects to the bond pad on the chip. It considers a popular type of such bonds known as `ball bond´. Using two-dimensional images taken from the top of the IC wafer, the system determines several geometric measures which are important in determining the quality of the bond. These measures include the boundary, length of major and minor axes of the best fitting ellipse and the center. The process utilizes automatic thresholding, morphological operations and geometric moments of the image. Success of the method is demonstrated through experimental studies on actual bonds