Abstract: The reliability of conductive circuitry of a printed circuit board and particularly the integrity of the conductive barrels of the through-holes is tested by cyclically passing a current through a plurality of interconnected barrels. The current must be sufficient to resistively heat the conductive barrels to a temperature at which the glass epoxy substrate adjacent to each barrel reaches a transition temperature at which the glass epoxy changes state from a solid to a semi-solid. After sufficiently heating the glass epoxy, it is allowed to cool to ambient temperature. This cycle is repeated for a predetermined number of cycles and the resistance of the barrels is measured after each cycle. A measured resistance that exceeds a predetermined value indicates that one or more defects is present in the interconnected barrels.