Water, although it is perceived as a hostile environment for electronics and from which, intuitively, we try to keep everything electronic, is, in fact, a very conducive environment for failure analysis. Indeed, with the acoustic analysis, we can find defects like bubbles or decohesions between two interfaces in an electronic module. During acoustic analysis, the room is immersed in a pool of water and a probe sends ultrasonic waves that will image the various interfaces of the room. Thus, depending on the signal reflection level, a gap or decohesion can be detected. A very practical analysis and ultimately not dangerous at all!