An ultrasonic microscope was designed and constructed to detect surface flaw defects on materials which contain natural discontinuities. The application of this flaw detection system to via-fill defects of single layer multiple layer ceramic substrates was considered. The microscope was evaluated for its depth sensitivity and resolution capabilities. The results of the experiment are that the ultrasonic system has repeatable depth sensitivities of better than ten microns, and resolution capabilities on the order of 3.3 cycles per millimeter. The application of the flaw detector to ceramic substrate via-fill defect inspection was verified
