Interfacial heat transfer and microstructural analyses of a Bi- 5% Sb lead-free alloy solidified against Cu, Ni and low-C steel substrates

• Published in: Journal of alloys and compounds Vol. 860; p. 158553
• Main Authors: Soares, Thiago, Cruz, Clarissa, Xavier, Marcella, Reyes, Rodrigo V., Bertelli, Felipe, Garcia, Amauri, Spinelli, José E., Cheung, Noé
• Format: Journal Article
• Language: English
• Published: Lausanne Elsevier B.V 15.04.2021; Elsevier BV
• Subjects: Alloys; Antimony; Bi-Sb alloy; Bismuth; Copper; Corrosion resistance; Corrosion resistant alloys; Heat transfer; Heat transfer coefficients; Heat transmission; Interface; Interface reactions; Lead free; Microelectronics; Microstructure; Nickel; Peritectic alloys; Phase diagrams; Resistance; Solidification; Substrates; Wettability; Wetting; Microstructure; Bi-Sb alloy; Heat transfer; Interface; Solidification
• ISSN: 0925-8388; 1873-4669
• DOI: 10.1016/j.jallcom.2020.158553

•A Bi-Sb lead-free alloy has been solidified against three substrates: Cu, Ni and Steel.•A proposed thermal/experimental approach has analyzed solder/substrates interaction.•Experimental solidification thermal history gives supports to the approach.•The wettability has shown not be the main factor controlling heat extraction. [Display omitted] Bi-Sb system alloys demonstrate high corrosion resistance and good wettability, becoming promising for use as lead-free solder alloys. The simplicity of the phase diagram is also a characteristic of this system, which is isomorphous forming the (Bi,Sb) phase. While extensive research has been performed on heat flow in couples of microelectronics surfaces with eutectic and peritectic alloys, literature regarding the issues of interfacial heat transfer between isomorphous alloys and microelectronics substrates is nonexistent. In this regard, the present research work demonstrates not only the application of a numerical mathematical model for thermal interface conductance but also wetting and interfacial reaction layer results in the formation of phases for the Bi- 5 wt% Sb alloy in different substrate materials. After carrying out the mentioned analyzes in three different conditions, Bi-Sb/copper, Bi-Sb/nickel and Bi-Sb/low-C steel, the wetting angle is shown not to be the predominant factor in controlling the interfacial heat transfer. Instead, the phases forming the interfacial layer from each of the tested substrates have a role in the heat transfer coefficients (h). In the case of the steel substrate, there is no layer formation, which allows greater contact conductance, whereas Bi-Sb/copper and Bi-Sb/nickel couples generate smaller h, being reasonably similar to each other.