Simulations of Microelectronic Packaging Reliability

Microelectronic packaging plays a vital role in semiconductor devices. With Moore’s Law nearing its limits, packaging is gaining interest to overcome the challenge. Wire bonding and solder joints are two major interconnections in electronic packaging. They are both widely used based on the requirement of the packaging. Here provides mechanical models to understand the failure in both interconnections.

Cu (copper) wire-bonding technology is attracting attention in the electronics industry due to its low cost and high electrical and mechanical properties. However, Cu wire bonding is known for its susceptibility to corrosion. The lifetime of Cu wires is shorter than its gold (Au) counterpart. To enhance the use of Cu wires in microelectronic packages, here presents a new mechano-chemical model that couples corrosion, mechanical response, and fracture. The model is used to understand the failure of Cu wires on Al pads in microelectronic packages using a multi-phase field approach. Under high humidity environments, the Cu- rich intermetallic compound (IMC), Cu₉Al₄, formed at the interface between Cu and Al, undergoes a corrosion degradation process. The IMC expands while undergoing corrosion-inducing interface stresses that nucleate and propagate cracks along the Cu-rich IMC/Cu. The model predicts failure due to corrosion and cracking. The model developed can be extended to other systems and applications.

Sn (tin)-based solder joints are widely used to provide high-density interconnections in microelectronic packaging. However, under repetitive temperature cycling, Sn forms subgrains in high-strain regions, eventually leading to damage. Moreover, Sn’s highly anisotropic material properties can contribute to the subgrain formation. A crystal plasticity model incorporating Sn's anisotropic and temperature-dependent properties is utilized to study the deformation and subgrain formation in Sn solder joints. Lattice rotations are calculated to show subgrain structure. The model developed here aims to predict the reliability of Sn solder joints subjected to temperature cycling.