The effects of TiO2 nanoparticles addition on the thermal shock resistance, shear strength and IMC layer growth of SAC305 alloy

The present study explores the effect of nano-sized TiO2 ceramic particles on interfacial structure, creep and shear strength of eutectic Sn-3Ag-0.5Cu (SAC305 in wt.%) interconnect material under isothermal aging and thermal shock cycles. The study revealed that the non-reacting and non-coarsening TiO2 nanoparticles improved the creep, shear strength and thermal shock resistance through refined the structure. An interfacial microstructural analysis confirmed that a layer types Cu6Sn5 and Cu3Sn phases are grown at the interface of SAC305/Cu system. When SAC305 was in contact with the Au/Ni-plated Cu pad ball grid array (BGA) substrate, a ternary (Cu, Ni)-Sn phase was detected. The thickness of IMC phase is increased with the aging time. However, the growth of IMC layer as well as the IMC phases inside the matrix e.g., Ag3Sn, Cu6Sn5, and AuSn4 is slower in the composite interconnection systems than that of reference interconnection systems. Furthermore, during the thermal shock cycles some micro-cracks are found at the interface and matrix regions in the reference interconnection systems. The measured shear strength of composite interconnections exhibited higher values as compare to the reference interconnection systems. However, the thermal shock cycles degrades the shear strength of interconnection faster than the situation in isothermal aging.