Grants and Contributions:

Grant or Award spanning more than one fiscal year (2017-2018 to 2018-2019).

Prior to the implementation of Restrictions on Hazardous Substances (RoHS) regulations in 2006, Sn-Pb alloysx000D
had been the predominant solder alloy in electronic industry due to their low cost, low melting temperature,x000D
excellent wettability and good reliability. Since 2006 there has been considerable debate and distress over whatx000D
alloy would replace dependable Sn-Pb. A Pb-free alloy made up of tin, silver (3.0%) and copper (0.5%)x000D
(SAC305) emerged as the industry standard during the RoHS transition because of its reasonable performance,x000D
low melting point compared to other alloys under consideration and compatibility with existing materials andx000D
processes. However, in the ensuing decade, electronic devices have been introduced in a myriad of newx000D
applications. For example, in automotive applications, in addition to basic on/off switches, there are nowx000D
autonomous brake control systems, electronically controlled shock absorbers, hybrid power control systemsx000D
and LED lighting. With the increasing variety and density of electronic devices, their role to ensure the safetyx000D
of the vehicle and occupants becomes very critical. Therefore, the challenge is to guarantee the performancex000D
and reliability of car electronics is greater than ever. For such applications the traditional SAC305 or similarx000D
alloys with poor creep resistance and unstable mechanical performance are not sufficiently reliable. Whenx000D
exposed to high service temperatures and thermal cycling, SAC305 undergoes significant microstructurex000D
change, specifically, the coarsening of Ag3Sn and Cu6Sn5 particles, which leads to degradation of mechanicalx000D
properties and poor creep resistance. Therefore, the electronics industry needs a new solder alloy with betterx000D
reliability than SAC alloys. To improve reliability of SAC alloys, alloying with Bi, Sb, In, Mn, Ni et al. hasx000D
been studied and suggested by some researchers. In order to develop a reliable solder alloy for high temperaturex000D
and demanding applications, further improvement of SAC-Bi alloy has been studied. In this project a newx000D
SAC-X solder alloy (X represents alloying additions Bi, Sb, Ni,...) with better reliability is introduced andx000D
studied. The main objective of this project is to study effects of thermal cycling on the microstructure evolution