Abstract:
This thesis explores the effects of adding indium (In) and silver (Ag) to tin-bismuth (Sn-Bi) solder alloys, focusing on their microstructural, thermal, and mechanical properties. As the electronics industry moves towards lead-free alternatives, optimizing solder alloy compositions becomes critical for performance and reliability. Through comprehensive analysis using Differential Scanning Calorimetry (DSC), Scanning Electron Microscopy (SEM), and mechanical testing, the study highlights significant enhancements brought by indium and silver additions.
Indium contributes to a refined microstructure by promoting uniform phase distribution and stabilizing grain boundaries, leading to reduced segregation and smaller grain sizes. This uniformity enhances the alloy’s ductility and mechanical stability, making it less prone to cracking under stress. Silver, on the other hand, enhances tensile strength and hardness through the formation of intermetallic compounds such as Ag3Sn. These compounds improve load-bearing capacity and contribute to the alloy’s overall mechanical strength.
Combined, the additions of indium and silver result in superior thermal fatigue resistance, crucial for electronic components subjected to repeated thermal cycles. Moreover, the improved joint reliability in soldered connections ensures more robust and durable electronic assemblies.
This research provides valuable insights into the synergistic effects of indium and silver in Sn-Bi solder alloys, offering a pathway to developing more reliable and efficient lead-free solders for modern electronic applications. The findings pave the way for further innovations in solder alloy formulations, ensuring better performance and longevity of electronic devices in an increasingly demanding technological landscape.