Recent challenges, advancements, and effects of nanoparticles on the low-temperature Sn-Bi solder alloys

There has been a notable increase in the use of solder connections within the advanced packaging industry. Recently, the application of the most used eutectic lead (Pb) based alloy has been restricted due to the high toxicity of Pb. This stimulated the researchers mind to develop “Pb-free” solder alloys that should compete with the benchmark properties already set by Pb-based alloys. Sn-Bi alloy has proven its potential as a low-temperature solder in microelectronics. Despite being superior in melting point, it has some obstacles that question its durability and reliability. This review provides a detailed overview of the properties, recent trends, and ongoing research activities revolving around the Sn-Bi solder. It highlights novel ideas and methodologies to utilize reinforcements such as metal nanoparticles (Nps), rare earth elements (REEs), ceramic Nps, etc. These additives are prone to enhance mechanical properties, control interfacial reactions, and refine microstructures. The insightful discussion about the strategies to reduce Bi-rich phase coarsening and improve ductility with detailed analysis of solder-substrate interaction, and intermetallic compounds (IMCs) formation paves the way for upcoming researchers. Furthermore, this review differentiates the critical gaps in the current articles, including a limited understanding of long-term reliability under mechanical and thermal stress. We believe that the highlighted comprehensive resources will be helpful for researchers working to optimize Sn-Bi alloys for advanced packaging technologies. The insights presented aim to facilitate the development of next-generation low-temperature solders that meet the rigorous demands of modern electronics. The review article explores the use of nanoparticles to tackle the brittleness of SnBi solder alloys, a significant challenge in microelectronic packaging. It begins by outlining the limitations of solder alloy, mainly focused on mechanical failures and then highlights how incorporating nanoparticles can refine the microstructures and enhance interfacial bonding. The article delves into solid formation processes, emphasizing the role of nanoparticles in forming robust intermetallic compounds and optimizing the solder matrix. Key outcomes include improved tensile strength, ductility and thermal cycling reliability. Finally, future directions for eco-friendly and low-temperature nanoparticle-reinforced solders are discussed, providing a comprehensive roadmap for advanced solder technology. • Low-temperature Sn-Bi solder alloy. • Surface finishing Treatments. • Formation of intermetallic compounds. • Effect of nanoparticles on Sn-Bi solder. • The challenges and prospects of Sn-Bi solder alloys.