Automated Inspection Of IC Bonding Wires Using Hough Transforf4
In this paper, we describe an algorithm developed to inspect bonding wires which connect the die to the package lead frame. The wire inspection algorithm first generates the wire candidate points using a simple one-dimensional gradient thresholding technique before calculating the Hough arrays for each of the candidate points. The latter operation involves the line-to-point Hough transformation in which wires are to be represented by straight lines having parameters ( p , e ) , where p is the distance of the line to the center and e is the inclination angle of the normal to the line. Apart from being able to count the wires and hence capable of detecting wire count aberrations, this algorithm can also detect crossing wires.