Effect of Au-deposited ceramic nanoparticles on SAC305/Cu solder joints

Abstract

This work considers ways to increase the stability of solder joints in a wide range of temperatures, which are extremely important in microelectronic devices. For this purpose, the effects of adding nanosized ceramic admixtures Al₂O₃, SiO₂, TiO₂, and ZrO₂ coated by Au into the Sn–3.5Ag–0.5Cu lead-free solder alloys on the microstructure and shear strength of the joints between the nanocomposite solder and a copper substrate were studied both at room temperature, as well as after a two-month exposure at sub-zero temperatures. The uncoated and Au-deposited ceramic nanoparticles were analyzed by transmission electron microscopy, and EDS elemental analysis reflected their distribution in the solder material. The microstructure analysis of the solder joints was carried out using the scanning electron microscope. The push-off experimental method was applied for determination of the shear strength, one of the most important mechanical properties of soldered joints. The obtained experimental results indicate that addition of the nanosized ceramic admixtures sputtered with gold to the basic solder matrix leads to a decrease in the growth rate of intermetallic layers in the soldered joints. The result is an improvement in the shear strength of these joints. Similar studies conducted after samples were kept for 2 months at 253 K (− 20 °C) did not lead to a significant deterioration of shear strength, which indicates their suitability to be used for soldering parts of microelectronic devices operating not only at room and elevated temperatures but also at sub-zero temperature range.