Labeled projection of digital images

DETAILED DESCRIPTION The invention comprises a method and apparatus for measuring the size and position of bonds 09 made by wire bonding machines in the semiconductor assembly process.
The invention calculates measurements from digitized images of the ball bonds 09, which have been captured by a video camera 04 and then digitized to form an array of pixels in computer memory.
In one preferred embodiment, the apparatus constructs a rectangular to polar coordinate transform image 60 having an image size and radius value at least equal to the maximum size and radius values of the expected ball bond to be inspected.
In another preferred embodiment the polar coordinate transform image 60 is created with multiple segments 65.
Ball bond image 70 and a nominal location of its center are obtained from the image processor 06 according to the methods and apparatus of the above-referenced pending U.
S.
patent applications.
Polar coordinate transform image 60 is aligned with the nominal location of the ball bond center.
Ball bond image 70 is evaluated by creating a one-dimensional polar projection histogram array using the polar coordinate transform image 60 to index through the array for storing and normalizing the histogram results.
An edge filter is applied to the projection to locate peaks, whose number and location for that nominal center are stored.
The invention repeats the alignment, evaluation, edge filtering and peak storing steps on a next potential ball center location until some specified number of potential locations have been evaluated.
The maximum peak is detected from all locations evaluated, and that peak is used as the radius of the ball bond.
Size and position of bond 09 are computed from the radius of a ball bond image 70 having the maximum peak and are passed as signals to host controller 08 for further action in the assembly process.
It is an aspect of the present invention that it performs a fast rectangular to polar coordinate transform of the bond image pixels, to minimize processing time spent in inspection