Performance of SAC305 and SAC305-0.4La lead free electronic solders at high temperature

Abstract

Purpose Tin-Silver-Copper is widely accepted as the best alternative to replace Tin-Lead solders in microelectronics packaging due to their acceptable properties. However, to overcome some of the shortcomings related to its microstructure and in turn, its mechanical properties at high temperature, the addition of different elements into Tin-Silver-Copper is important for investigations. The purpose of this paper is to analyse the effect of lanthanum doping on the microstructure, microhardness and tensile properties of Tin-Silver-Copper as a function of thermal aging time for 60, 120 and 180 h at a high temperature of 150°C and at high strain rates of 25, 35 and 45/s. Design/methodology/approach The microstructure of un-doped and Lanthanum-doped Tin-Silver-Copper after different thermal aging time is examined using scanning electron microscopy followed by digital image analyses using ImageJ. Brinell hardness is used to find out the microhardness properties. The tensile tests are performed using the universal testing machine. All the investigations are done after the above selected thermal aging time at high temperature. The tensile tests of the thermally aged specimens are further investigated at high strain rates of 25, 35 and 45/s. Findings According to the microstructural examination, Tin-Silver-Copper with 0.4 Wt.% Lanthanum is found to be more sensitive at high temperature as the aging time increases which resulted in coarse microstructure due to the non-uniform distribution of intermetallic compounds. Similarly, lower values of microhardness, yield strength and ultimate tensile strength come in favours of 0.4 Wt.% Lanthanum added Tin-Silver-Copper. Furthermore, when the thermally aged tensile specimen is tested at high strains, two trends in tensile curves of both the solder alloys are noted. The trends showed that yield strength and ultimate tensile strength increase as the strain rate increase and decrease when there is an increase in thermal aging. Originality/value The addition of higher supplement (0.4 Wt.%) of Lanthanum into Tin-Silver-Copper showed a lower hardness value, yield strength, ultimate tensile strength, ductility, toughness and fatigue in comparison to un-doped Tin-Silver-Copper at high temperature and at high strain rates. Finally, simplified material property models with minimum error are developed which will help when the actual test data are not available.

Optimized cerium addition for microstructure and mechanical properties of SAC305

“…The microstructure of SAC alloy consists of soft primary Sn-dendrites with the eutectic colonies of hard and brittle IMCs (Cu 6 Sn 5 , Ag 3 Sn) (Gao et al , 2010). The characteristics of these IMCs influence the mechanical properties of the alloy (Aamir et al , 2015; Aamir et al , 2017a, Aamir et al , 2016; Aamir et al , 2019b, Sadiq et al , 2013). The rapid cooling rate ensured a fine grain structure of the alloy, but using this method induced residual thermal stresses and degraded the mechanical properties of the alloy (Sadiq et al , 2013).…”

“…The microstructure of SAC alloy consists of soft primary Sn-dendrites with the eutectic colonies of hard and brittle IMCs (Cu 6 Sn 5 , Ag 3 Sn)(Gao et al, 2010). The characteristics of these IMCs influence the mechanical properties of the alloy(Aamir et al, 2015;Aamir et al, 2017a, Aamir et al, 2016Aamir et al, 2019b,…”

Mechanical testing and characterization of tin–zinc–antimony–lanthanum lead-free solders produced using mechanical alloying and furnace melting techniques

“…Soldering is a joining technique used in electronic packaging (Kolenak, 2017). Tin-lead was a conventional solder in its early days, as most lead-based solders exhibit excellent flow characteristics, mechanical properties and low melting points (Aamir et al , 2019). For these reasons, tin-lead alloys were long the material of choice in the industry (Zhang et al , 2012 and Sunderraj et al , 2018).…”

A review: microstructure and properties of tin-silver-copper lead-free solder series for the applications of electronics

“…A thin layer of IMCs is required to attain a better metallurgical bond for the reliability of electronic solders; however, their higher growth has undesirable impacts on mechanical properties due to their brittle nature (Liang et al, 2014). Therefore, it is important to expand the knowledge of IMCs for the reliability of solder interconnections (Aamir et al, 2017c;Aamir et al, 2019). This brief review notes how the addition of alloying elements or composite approach into SAC series is discussed to highlight the impact of participates in suppressing the growth of IMCs for refined and uniform microstructures.…”