Effects of Indium on Wetting and Interfacial Features of a Sn-40Bi Alloy in a Copper Substrate

Author(s)

da Silva Leal, Jaderson Rodrigo ; Valenzuela Reyes, Rodrigo Andre ; de Gouveia, Guilherme Lisboa ; Coury, Francisco Gil ; Spinelli, Jose Eduardo

• Document type: Journal article
• Source: JOURNAL OF ELECTRONIC MATERIALS; v. N/A, p. 14-pg., 2023-02-07.

Abstract

The influence of In on the solidification path, microstructure, wettability, tensile properties, and interfacial features of a Sn-40Bi alloy was studied using Computer Coupling of Phase Diagrams and Thermochemistry (CALPHAD) calculations, differential scanning calorimetry, scanning electron microscopy, x-ray diffraction, wettability testing and tensile testing. The microstructures were composed of Sn-rich matrixes with Sn-Bi and BiIn-Bi constituents. Significant sensitivity of the microstructural scale to the solidification cooling rate was also demonstrated by employing different processing conditions. Because of the relatively high BiIn fraction on the microstructure, a limited elongation of approximately 7% was achieved, with ultimate tensile strength of 65 MPa. Cu-6(Sn, In)(5) was the intermetallic phase of the reaction film for the Sn-Bi-In/Cu interface under all tested conditions, including as-soldered and aged at 100 degrees C and 120 degrees C for 120 h, 240 h, and 360 h. Wetting angles for the ternary Sn-Bi-In alloy were maintained at approximately 20 degrees, which is smaller than usual for Sn-Bi alloys. The new phase, Cu-6(Sn, In)(5), produced instead of Cu6Sn5, showed a lower growth rate than that observed in In-free couples. The mechanisms of wetting and the Cu-6(Sn, In)(5)-layer growth are discussed. (AU)

• FAPESP's process: 19/23673-7 - Evaluation of alloys for thermal interface contact and for additive manufacturing
• Grantee: José Eduardo Spinelli
• Support Opportunities: Regular Research Grants
• FAPESP's process: 21/08436-9 - Electromigration and 4D microtomography in Sn-Bi-In thermal joints
• Grantee: José Eduardo Spinelli
• Support Opportunities: Scholarships abroad - Research