HIGH FREQUENCY ULTRASONIC EVALUATION OF POWER SEMICONDUCTOR DEVICES
Y. Shen, C. Ozzano, N. Pietranera, F. Rosatelli, E. Bellafronte*, M. Portesine* Ansaldo Ricerche srl, Corso F. M. Perrone 118, 16161, Genova, Italy *Ansaldo Trasporti, Unita Semiconduttore, Via N. Lorenzi 8, 16152 Genova, Italt
The joint quality between silicon wafer and Molybdenum disk has a decisive influence for the characteristics of the power semiconductor devices such as power diodes, thyristors and GTO. Ultrasonic examination has been applied to evaluate the joint quality in the manufacturing process. Owing to the small thickness (0.2-0.4mm) of the Silicon wafer, the pulse-echo method with high frequency (up to 80 MHz) transducers have been used. The debonding defects with dimension as small as 0.1 mm, created by the photolithography technique, have been clearly revealed. The joints obtained with different brazing procedures have been tested and their results have been compared with those of devices electrical property measurements and destructive tests.
Publication Source: Trends in NDE Science & Technology; Proceedings of the 14th World Conference on Non-Destructive Testing, New Delhi, 8-13 December 1996.full paper not received Publisher:Ashgate Publishing Company
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