What's inside my USB drive? — X-ray microscopy and X-ray nano CT for 3D packaging

Electronics and microsystems technology are characterized by an ongoing miniaturization and a growing up of complexity of semiconductor components. These trends are described by Moore's Law and the terms “More Moore” and “More than Moore” (see Fig. 1). The most important driver of this development is the respective market of the final products — driven by the costs. In this context the development of electronic and micro technical systems is inseparably connected with the corresponding electronics packaging and the required nondestructive testing methods. This paper presents fundamentals and applications for nondestructive evaluation of inner structures of electronics packaging for quality assurance and reliability investigations. The authors used two generations of conventional USB memory drives with stacked dies to present possibilities, evolution and limitations of high-resolution NDT methods for electronics packaging like X-ray diagnostics and Scanning Acoustic Microscopy. The focus is on the X-ray nano CT (computed tomography). As a highlight the paper describes the evaluation of wire bonding connections (gold wires) on a silicon die with copper metallization with X-ray nano CT.