Harsh service environment effects on the microstructure and mechanical properties of Sn–Ag–Cu-1 wt% nano-Al solder alloy
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This paper investigates the electrical and mechanical performances of eutectic Sn-3Ag-0.5Cu (wt%) solder with the addition of Al nanoparticles. The study revealed that the elastic moduli, electrical resistivity and damping properties of such solder alloy were improved. Further, interfacial reaction phenomena on Au/Ni-plated Cu pad ball grid array substrate during isothermal aging and thermal cycle was evaluated in terms of the formation and growth kinetics of intermetallic compound (IMC) layer. A structural analysis confirmed that at their interfaces a ternary (Cu, Ni)-Sn IMC layer was adhered at the substrate surface. The thickness of this IMC layer was increased with increasing the duration of the isothermal aging and thermal cycle without any defects. In addition, the formation of Ag3Sn, Cu6Sn5, Sn–Al–Ag and AuSn4 IMC phases were evenly distributed in the solder matrix which acts as the second phase reinforcement. The measured shear strength and microhardness indicated that the exposure of the solder joints to the thermal cycles make the joints degraded faster than the situation in isothermal aging.
KeywordsShear Strength Solder Joint Solder Alloy Composite Solder Isothermal Aging
The authors acknowledge the financial support provided by The University of New South Wales (UNSW) for the project InfoEd Ref: RG124326. The authors would like to thank EPA centre staff for using the facility to do the experiment. The authors would also like to thank Mr. Tit Wah Chan, Department of Physics and Materials Science, CityU, for helping the damping property measurement.
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