| 摘要 |
The invention automatically inspects the bond of a wire to a contact pad on a semiconductor chip. The apparatus includes a movable platform for holding semiconductor chips situated in lead frames; a video camera for sensing images; illumination means for illuminating a chip in a lead frame; an image processor to digitize and analyze the images; a bonding mechanism; and a host controller electronically connected to bonding mechanism, movable platform, video camera, and image processor. Image processor locates a bond on a pad in a digitized image and provides a first nominal center of ball bond image. The invention aligns the center of a polar coordinate transform image having one or more segments with the nominal center of ball bond image and evaluates ball bond image using the polar coordinate transform image to create a polar projection histogram array and store it. An edge filter is applied to histogram array to detect peaks and store their number and values. Polar coordinate transform image is aligned with a next nominal ball center location until a predetermined number of potential ball center locations is exhausted. The maximum peak in the list of stored peaks is selected as the radius of bond from which the size and position of bond is computed and reported to host controller for further action. |
