Research and development of lead-free solder for microelectronics in consideration of the environmental and qualitative aspects

Abstract

The paper deals with the research and development of lead-free solder for microelectronics in consideration of the environmental, economic, and qualitative aspects. The main aim of this paper is to study the influence of In additives to the complex properties of solder joints. The SnCu0.67In2.0 solder alloys were used for the research. They had been confronted with the most commonly used SnAg3.0Cu0.5 solder in the electronics industry in terms of melting temperatures, wetting properties, microstructures, and costs. Thermo-Calc software was used for phase’s composition prediction. The solder joint reliability was assessed to evaluate the thermal cycling test in the range from −40 to 150 °C. Altogether, 1,500 cycles were carried out. Solder joints were exposed to the thermal cycling due to practice requirement. Optical microscopy, scanning electron microscopy (EDX microanalysis), and shear strength test were used for the evolution of microstructure, structural integrity, and mechanical strength of thermal-cycled solder joints. Designed SnCu0.67In2.0 solder alloys reached the most suitable result for microelectronic.