2012 Volume 98 Issue 11 Pages 575-582
Nondestructive ultrasound imaging system is the most popular industrial evaluation technique for various bonding interfaces, such as a composite materials and IC products and so on. This method is widely known as a reliable evaluation technique even for the strength of the bonding. However recently, some reports pointed out that the conventional ultrasound imaging system may miss detect the special bonding interface so-called kissing bond which the bonding interfaces are contact but no joining.
In this study, we would like to mix the subharmonic ultrasound mainly investigated as the advanced crack evaluation technique to the ultrasonic imaging system and to develop the new nonlinear ultrasound image system. The new imaging equipment in which all the RF waveforms were digitized for ultrasonic advanced imaging and the new designed high aspheric surface acoustic lens to obtain higher amplitude ultrasound were combined. Furthermore, the wavelet analysis for all the RF waveform could be used to obtain any frequency image. Thus both the fundamental frequency ultrasonic imaging and the subharmonic ultrasonic imaging could be obtained using the developed ultrasonic imaging system. As a sample of the bonding interface, industrial diffusion bonding structure was used and the diffusion bonding was controlled by nm order in thickness including the difficult bonding interface to detect by the conventional system, and the availability of the newly developed ultrasonic measurement system was investigated.