The present invention provides a method for detecting and adjusting failed back-drills in PCBs in the process of fabricating a PCB so that the failed back-drill can be screened out or repaired. This is accomplished, by after detecting poor back drills in a PCB, measuring the actual thickness of each PCB board. Next, the measured actual thickness of each PCB board is compared with .the theoretical thickness of each PCB board. The back drill depth for each area of the PCB board is then adjusted for its theoretical thickness and percent variation from the measured thickness to adjust the poor back drill.