Effect of Peak Temperature on SAC Nano-Reinforced Fillet Height

Abstract

Recently, the addition of new materials into the conventional solder pastes provides a viable solution to optimize the material characteristics and properties of the nano-particle filled solder paste. Addition of titanium oxide (TiO₂) nanoparticles shown that it can enable better performance of the solder. However, actual industry experiment in terms of its optimum thermal profile for improved strength through good spread of nano-particles in the solder is very costly and lengthy to set up. Hence, this paper presents a preliminary study of the interaction between two models of numerical simulation namely volume of fluid (VOF) and discrete phase model (DPM) then compare with previous experimental data. This paper aims to analyse the effect of peak temperature towards the fillet height of ultra-fine Sn-Ag-Cu (SAC) solder joints doped with TiO₂ nanoparticles in an electronic assembly. For the purpose of this research, the weight percentage of the nanoparticles TiO₂ with the SAC305 lead-free reinforced solder is varied at different peak temperature and investigated in terms of particles distribution, fillet height and thermal strain. This paper presents a 3D numerical simulation of nano-reinforced lead (Pb)-free solder at the ultra-fine joint component for 01005 capacitor with dimension of 0.2 x 0.2 x 0.4 mm³. The results obtained are confirmed by conducting an experiment using a field emission scanning electron microscope (SEM) joined with an EDS and X-ray diffraction machine. This study concludes that the best fillet height would be obtained at 250°C. The distributions of nanoparticles with 0.01 wt%, 0.05 wt%, and 0.15 wt% of weighted percentage are effectively observed by using the HRTEM analysis. Based on the study, higher temperature of the wetting region that range between 240°C and 255°C results in better particle distributions, and fillet height of the solder by using temperature in that range meets the requirement of IPC standards.