Suitability of X-Rays
If possible, analysis techniques must not damage the piece which has the fault. This is important for random sampling purposes and for the analysis of some expensive components. Techniques such as using electron microscopes, for example, necessitate careful preparation like smoothing out the surface thereby damaging it. Analyzing a sample without damaging it is called Non-Destructive Testing (NDT).
X-Ray imaging is ideal for NDT techniques for several reasons. In the first place, X-rays have tiny wavelengths which are much smaller than those possessed by visible light. This allows very high-resolution x-ray images to be taken which becomes more and more important as the size of components decreases. The amount of energy carried by the X-rays which translates into greater or lesser wavelengths as dictated by Planck's hypothesis can be varied depending on the requirements.
Second, the penetrating power of X-rays allows engineers to get an in-depth look at the internal structure of components just like doctors use them to peer inside the human body. 2D micrographs present images in two dimensions with components overlapping each other. While this can be useful in many circumstances, we're increasingly turning to a 3D x-ray image in order to get a clearer picture of the insides. In fact, 3D imaging will soon become the most important technique used due to the greater complexity of modern ICs.
Sophisticated X-Ray analysis techniques also rely on tools which allow analysis experts to mount the sample and use joystick-like controls to rotate it, thus enabling them to gain a much better understanding of its structure. Failure analysis using high-resolution x-ray systems are therefore an indispensable component of the process of figuring out the weaknesses in an electronic system.