Poster Presentation

¹Mostafa Beitsode; ¹Ali Mohammad Hhadian ; ²Cyrus Zamani

¹School of Metallurgy and Materials Engineering, College of Engineering, University of Tehran, Tehran, Iran

²School of Metallurgy and Materials Engineering, College of Engineering, University of Tehran

In present study the microstructure and mechanical properties of Sn-57Bi-1Ag based composite solder joints reinforced by different amounts of 〖Al〗_2 O_3 whisker were investigated. By addition of different amounts of〖 Al〗_2 O_3, solder microstructure, interfacial microstructure, shear strength and fracture surfaces of the joints were investigated. Microstructural examinations were done using scanning electron microscope (SEM). An Energy Dispersive Spectrometer (EDS) was employed for elemental analysis. The shear strength of the soldered samples was measured using a shear testing method. All fracture surfaces were observed by field emission scanning electron microscope (FSEM) to reveal the fracture mechanism and morphologies. The results show that addition of Al2O3 whisker in a proper amount reduces the grain size of the microstructure and improves the strength of the joints. Addition of 0.25 wt% ceramic reinforcement to the composite increased shear strength up to 24% (from 49/3MPa to 61/1MPa). In addition, when the amount of Al2O3 whisker increased to 0.25 wt%, a layer of intermetallic compounds (IMCs) formed between the bulk solder and the Cu substrate. It was also revealed that scallop-shaped Cu6Sn5 IMC morphology became slightly flattened, which caused the fracture path to shift from the IMC/solder interface to inside the solder matrix.

: Lead-free solder; Al2O3 nano whisker; Mechanical alloying; microstructure; Mechanical properties