The present invention relates to the marking and identification of defective die sites on a mounting substrate. A mounting substrate is provided which is inspected and tested for visual and electrical defects. Information relating to the functionality and/or various defects of one or more die sites is then encoded in the form of a designator placed on the substrate. The information encoded on the designator may then be read or scanned by, for example, computer-driven video equipment and used in a die-attach process to discriminately place semiconductor dice only on known good die sites. Embodiments of the designator include information encoded in the form of a bar code, a series of identifying marks, a strip of magnetic tape or a computerized map of a mounting substrate. Correlated data regarding die site functionality can then be electronically transferred to a die-bonding apparatus.