Impact of Electrical Current Stressing on η'-Cu6Sn5 in Electronics Packaging

In advanced electronic packaging, the stability of intermetallic compounds (IMCs) under high electric current density is crucial for the reliability of solder joints. Cu6Sn5, a predominant IMC formed between Sn-based solders and Cu substrates, exists in two allotropes: the high-temperature hexagonal phase and the low-temperature monoclinic η' phase, with a transition temperature of 186°C. This study investigates the effects of electric current on η'-Cu6Sn5 phase, focusing on structural characterization and mechanical properties. Various electric current densities were applied to thermally aged η'-Cu6Sn5. Synchrotron radiation-based X-ray diffraction (SR-XRD) was used to examine crystallographic changes, while nanoindentation tests assessed mechanical property alterations. These observations contribute to understanding the impact of electric current density on the structural and mechanical behavior of the monoclinic η'-Cu6Sn5 phase.