Effects of ZrO2 nanoparticles on the mechanical properties of Sn42Bi58 solder joint

Lead-free solder has been used to replace toxic lead-containing solder. Sn42Bi58 solder has attracted a lot of attention for its low-cost, low melting temperature. Nanoparticles, such as metallic, nonmetallic and oxidant, have been doped into solders to improve their performance. In this study, we investigated the effect of ZrO2 nanoparticles on the mechanical properties of Sn42Bi58 solder joints. Firstly, solder balls were made from solder paste by stencil printing and reflow. Next, solder balls were reflowed to form solder joints on Cu pad metalized with Au/Ni layers. Then, solder joints were put into an isothermal aging oven for different aging time. Shear tests were performed to investigate the shear strength of both solder joints subjected to aging time. Scanning electron microscope (SEM) was employed to study microstructure evolution in solder matrix. The results showed that the shear strength of Sn42Bi58 solder joints was reinforced with the incorporation of ZrO2 nanoparticles. The growth of intermetallic compounds (IMCs) in ZrO2 doped solder joints was observed to be impeded.