Interfacial characteristics of solder joint in electronic packaging

Abstract

Electronic packaging is the hardware structure used for the housing and interconnection of integrated circuits (ICs) that form electronic systems. Recently, microelectronic devices and systems have experienced rapid development. The interest, demand, and application of flexible, wearable, and foldable electronics using flexible substrates have also rapidly increased. Until now, in electronic materials, Pb-Sn solder has been used for the interconnection between chips and substrates. However, Pb-free soldering materials with Sn as the main element have been proposed in order to eliminate Pb, because of increased environmental concerns. Sn-based Pb-free solders, in which Sn reacts with the surface finishing or substrate pad materials and thereby forms intermetallic compounds (IMCs) at the joint from the interfacial reactions occurring between the solder and the substrate finish material during soldering, such as the reflow process. These interfacial reactions and IMCs can affect the reliability of the solder joints and the rapid growth of IMCs can cause degradation of the mechanical properties and reliability of the joints. Therefore, electronic packaging technology of the past focused on the physical protection of the chip or the electronic connection between chips, or between the chip and the substrate, whereas the packaging technology of today must address issues of the properties and reliability of the joints between the chip and the package substrate and those among multiple chips and packages. In this dissertation, new approaches are discussed to improve the interfacial characteristics and reliability of solder joints in electronic packaging using graphene and flexible substrate.