Thermal analysis and characterization of Sn-based solder alloy the for cryogenic applications

• Grant number: 15/03923-8
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: May 01, 2015
• End date: July 31, 2015
• Field of knowledge: Engineering - Materials and Metallurgical Engineering - Physical Metallurgy
• Principal Investigator: Conrado Ramos Moreira Afonso
• Grantee: Felipe Dantas Barbosa
• Host Institution: Centro de Ciências Exatas e de Tecnologia (CCET). Universidade Federal de São Carlos (UFSCAR). São Carlos , SP, Brazil

Abstract

Currently, the traditional Sn-Pb alloy brazing is being replaced by alternative alloys in view of the recognized lead toxicity, the total ban of the industrial environment is inevitable. The deposition process or soldering is widely applied at the junction of microelectronic components. The eutectic Sn-Pb alloys have particularly exceptional properties for this application: low melting point (183 ° C), excellent wettability with the metal substrate, good fluidity, and mechanical properties suitable. Although the Sn-Cu eutectic alloy is an economically feasible alternative to Pb-Sn, research efforts should be implemented to improve the properties of alternative Sn alloys. In aerospace applications, it is important to understand the mechanical performance components under extreme temperature conditions observed in service. For solder alloys used in microelectronics, cryogenic temperatures can be problematic. The low-temperature Sn-based solder may undergo a ductile to brittle transition that leads to brittle cracks, which can result in catastrophic failure of electronic components, assemblies, and spacecraft payloads. As industrial processes begin to move away from Pb solder alloys, Sn, making it even more critical the need to characterize the behavior of the solder of Sn-based alloys alternatives. The objective of this project is the microstructural characterization and thermal analysis of alloy Sn solder to several bases to assess their potential for cryogenic applications. The aim is to identify different systems Sn alloy with addition of alloying elements which influence the allotropic transformation of the ²-phase to ± Sn-Sn phase (pure Sn around 13 ° C), in order to identify and characterize this alloy having ² transformation temperature (ductile) to ± (brittle) at lower temperatures (cryogenic), avoiding brittle-ductile transition and extending the temperatures range of cryogenic application of Sn solder alloys.