Comparative Analysis of SAC Solder Alloys for Enhanced Reliability in Electronic Assemblies: A Finite Element Approach

Abstract In an era where environmental sustainability and electronic reliability are paramount, this study provides a critical quantitative analysis of lead-free Sn-Ag-Cu (SAC) solder joints, employing Finite Element Analysis (FEA) to scrutinise their thermomechanical fatigue and creep deformation characteristics. The investigation juxtaposes four SAC solder alloys (SAC305, SAC387, SAC396, and SAC405) against traditional lead-based Sn63Pb37 solder to elucidate their microstructural evolution and ensure long-term reliability. FEA simulations disclose that SAC387 alloy exhibits the highest yield stress at 58 MPa, whereas SAC405 shows remarkable resilience with the lowest stress accumulation, characterised by σ = 1.543T – 34.983. Isothermal ageing studies demonstrate SAC387’s accelerated creep response, indicating a higher susceptibility to failure. Conversely, SAC405's steadfast nature under isothermal ageing is marked by the least strain and deformation rates, enhancing its reliability. Strain distribution analyses further reveal that SAC405 alloys endure the lowest strain levels, contrasting with SAC387, which experiences substantial deformation and leads to strain energy density—a key longevity indicator. Thus, SAC405 and Sn63Pb37 record the lowest strain energy densities, highlighting their robustness. These findings provide a comprehensive assessment of SAC solder alloys, focusing on their stress, strain, energy density, and strain rates. The reliance on FEA for predictive analysis indicates the potential for pre-empting failure, offering a valuable framework for electronic manufacturers in selecting and optimising solder materials. This study illuminates the intricate dynamics of SAC solder joints under thermomechanical stress, serving as an indispensable resource for designing robust and sustainable electronics that align with the industry’s environmental responsibilities.