Simulação computacional aplicada ao estudo de juntas sn-bi-in/cu e sn-bi-zn/cu unidas por soldagem branda

Abstract

This work assessed the TCSLD3 database use for designing solder alloys of the Sn-Bi-In and Sn-Bi-Zn systems using the Thermo-Calc software and CALPHAD method. The thermodynamic analyses went through a preliminary detailing of the Sn-Bi and Cu-Sn binary systems, progressing to the study of the ternary systems of interest in order. As such, the final optimal compositions could be defined, leading, in the final steps, to the addition of copper in each one of the selected alloys. Initially, for the binary systems, small differences from the data provided in the literature were found. For the Sn-Bi-In system, the optimized Sn-53.55%Bi-2%In (in wt. %) alloy presented a liquidus temperature (TL) of 122.3°C and a solidification interval of 12.2°C. For Sn-Bi-Zn system, the eutectic Sn-50.53%Bi-2.28%Zn alloy composition was found with a TL of 130.3°C. In both cases, a reliable correlation with the data available in other studies was verified. Additionally, the method for simulating the effect of the contact with a copper substrate indicated satisfactory results regarding the identification of the expected Cu-containing phases. In the Sn-Bi-In system, the TCSLD3 database could describe the admission of the In element replacing Sn within the Cu6Sn5 and Cu3Sn intermetallics. In the matter of the Sn-Bi-Zn system, the main phase responsible for suppressing the formation of the two aforementioned intermetallics, Cu5Zn8, had its stability indicated for Cu contents between 0.5% and 1.0%, i.e., preceding the formation of the Cu6Sn5 and Cu3Sn intermetallics observed at intermediate contents.