Improvement in the mechanical properties of eutectic Sn58Bi alloy by 0.5 and 1 wt% Zn addition before and after thermal aging

Zhou, Shiqi; Mokhtari, Omid; Rafique, Muhammad Ghufran; Shunmugasamy, Vasanth Chakravarthy; Mansoor, Bilal; Nishikawa, Hiroshi

doi:10.1016/j.jallcom.2018.06.121

Cited by 69 publications

(32 citation statements)

References 44 publications

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“…The phenomenon of microstructure refinement is commonly observed in microalloyed, low-temperature solder alloys [23][24][25][26][27][28][29]40]. By microalloying Ag, the microstructure of Sn58Bi alloy becomes more refined whilst Ag 3 Sn intermetallic compounds form.…”

Section: Discussionmentioning

confidence: 99%

Improved Reliability and Mechanical Performance of Ag Microalloyed Sn58Bi Solder Alloys

Ren

Collins

2019

Metals

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Ag microalloyed Sn58Bi has been investigated in this study as a Pb-free solder candidate to be used in modern electronics industry in order to cope with the increasing demands for low temperature soldering. Microstructural and mechanical properties of the eutectic Sn58Bi and microalloyed Sn57.6Bi0.4Ag solder alloys were compared. With the addition of Ag microalloy, the tensile strength was improved, and this was attributed to a combination of microstructure refinement and an Ag3Sn precipitation hardening mechanism. However, ductility was slightly deteriorated due to the brittle nature of the Ag3Sn intermetallic compounds (IMCs). Additionally, a board level reliability study of Ag microalloyed Sn58Bi solder joints produced utilizing a surface-mount technology (SMT) process, were assessed under accelerated temperature cycling (ATC) conditions. Results revealed that microalloyed Sn57.6Bi0.4Ag had a higher characteristic lifetime with a narrower failure distribution. This enhanced reliability corresponds with improved bulk mechanical properties. It is postulated that Ag3Sn IMCs are located at the Sn–Bi phase boundaries and suppress the solder microstructure from coarsening during the temperature cycling, hereby extending the time to failure.

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Section: Discussionmentioning

confidence: 99%

Improved Reliability and Mechanical Performance of Ag Microalloyed Sn58Bi Solder Alloys

Ren

Collins

2019

Metals

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“…This phenomenon of microstructure refinement is commonly observed in micro-alloyed low temperature solder alloys [22][23][24][25][26][27][28]38]. By micro-alloying Ag, the microstructure of Sn58Bi alloy becomes more refined whilst Ag3Sn intermetallic compounds form, and these intermetallics enhance strength through a precipitation hardening mechanism which in turn deteriorates ductility due to their inherent brittleness.…”

Section: Discussionmentioning

confidence: 89%

“…Ni was found to refine the initial microstructure and enhance the tensile strength [22]. Zn was found to refine the microstructure as well as supress the microstructure coarsening during aging, resulting in improved elongation and ultimate tensile strength (UTS) both before and after thermal aging [23]. Ti was also found to refine the microstructure, improve both UTS and yield strength (YS), even after aging [24].…”

Section: Introductionmentioning

confidence: 96%

Improved Reliability and Mechanical Performance of Sn58Bi Solder Alloys

Ren¹,

Collins²

2019

Preprint

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Microstructural and mechanical properties of the eutectic Sn58Bi and micro-alloyed Sn57.6Bi0.4Ag solder alloys were compared. With the addition of Ag micro-alloy, the tensile strength was improved and this is attributed to a combination of microstructure refinement and an Ag3Sn precipitation hardening mechanism. However, ductility is slightly deteriorated due to the brittle nature of the Ag3Sn intermetallic compounds (IMCs). Additionally, a board level reliability study of Ag micro-alloyed Sn58Bi solder joints produced utilising a surface-mount technology (SMT) process, were assessed under accelerated temperature cycling (ATC) conditions. Results reveal that micro-alloyed Sn57.6Bi0.4Ag has a higher characteristic lifetime with a narrower failure distribution. This enhanced reliability corresponds with improved bulk mechanical properties. It is postulated that Ag3Sn IMCs are located at the Sn-Bi phase boundaries and suppress the solder microstructure from coarsening during the temperature cycling, hereby extending the time to failure.

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“…Minor doping to adjust the properties of Sn-Bi alloys has been extensively studied [12,13,14,15,16,17,18,19,20,21]. For instance, it was found that 0.1 wt.% Cu addition in Sn-40Bi solders resulted in an increase in both ultimate tensile strength (UTS) and ductility, while 2 wt.% Zn addition in Sn-40Bi-0.1Cu could further enhance UTS, but decreased the elongation remarkably [17]; 0–2 wt.% Zn addition could increase the UTS and effectively suppressed the coarsening of (Bi) phase in Sn-Bi solders [18,19]; 0.5 and 1 wt.% nickel (Ni) addition improved the ductility of eutectic Sn–58Bi [15]; 0.25–0.5 wt.% Ag addition in near-eutectic Bi–45Sn alloys improved their ductility [20]; and among Ag, Cu, Zn, and antimony (Sb) as the doping elements for Sn-Bi alloys, 0.5 wt.% Ag addition increased the tensile strength the most, while 0.5 wt.% Cu and Sb improved the elongation significantly but changed the tensile strength slightly [21]. In particular, Chen et al [13] showed that a proper amount of In addition in the eutectic, the Sn-58Bi alloy could not only lower the melting temperature, but also improve the elongation.…”

Section: Introductionmentioning

confidence: 99%

“…The positive alloying effects can generally be categorized into two kinds as follows. Firstly, the alloying effects may induce solidification of phases with higher liquidus temperature, such as (Zn), Ag 3 Sn, Cu 6 Sn 5 , Ni 3 Sn 4 , and SnSb, which act as extra heterogeneous nucleation sites and prohibit grain growth of both (Sn) and (Bi) phases [15,17,18,19,20,21]. The resultant refined microstructure could neutralize the brittle property of (Bi) phase and consequently exhibit better mechanical properties.…”

Section: Introductionmentioning

confidence: 99%

A Computational Thermodynamics-Assisted Development of Sn-Bi-In-Ga Quaternary Alloys as Low-Temperature Pb-Free Solders

et al. 2019

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Low-temperature lead (Pb)-free solders are demanding in the electronic packaging industry, because it would open the door for various economic choices of polymeric materials as substrates and also revives the lower cost processes. Here, we proposed a tin–bismuth–indium–gallium (Sn-52.5Bi-2.68In-1Ga, SBIG (in wt.%)) quaternary low-temperature solder, designed based on systematic CALPHAD (CALculation of PHAse Diagram)-type thermodynamic calculations and corresponding key experiments. The solidification behavior of SBIG was carefully elaborated based on the computations using the lever rule and the Scheil model, and the experiments in terms of thermal analyses and microstructures of sample produced with step-quenching and various cooling rates. The mechanical properties of as-cast and 80 °C-annealed SBIG as well as their microstructures and fracture surfaces were evaluated in the tensile tests. The proposed SBIG solder is with a low liquidus temperature of 141.9 °C and is typically composed of the primary (Sn) phase, the (Sn) + (Bi) eutectic structure and a small amount of (Ga) phase. Air cooling has been identified as a satisfactory cooling rate, which would not lead to the formation of the brittle BiIn intermetallic compound. The as-cast SBIG solder exhibited high yield strength (YS) of 43.7 MPa, high ultimate tensile strength (UTS) of 53.3 MPa and an extremely large elongation of 97.3% as comparing to the conventional eutectic Sn-58Bi solder (YS: 43.1 MPa, UTS: 49.5 MPa, and elongation: 37.5%). However, the proposed SBIG solder does not possess qualified thermal stability, that significant degradation in both strength and elongation were observed after being subjected to extensive thermal ageing at 80 °C for 504 h.

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Improvement in the mechanical properties of eutectic Sn58Bi alloy by 0.5 and 1 wt% Zn addition before and after thermal aging

Cited by 69 publications

References 44 publications

Improved Reliability and Mechanical Performance of Ag Microalloyed Sn58Bi Solder Alloys

Improved Reliability and Mechanical Performance of Ag Microalloyed Sn58Bi Solder Alloys

Improved Reliability and Mechanical Performance of Sn58Bi Solder Alloys

A Computational Thermodynamics-Assisted Development of Sn-Bi-In-Ga Quaternary Alloys as Low-Temperature Pb-Free Solders

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Improvement in the mechanical properties of eutectic Sn58Bi alloy by 0.5 and 1 wt% Zn addition before and after thermal aging

Cited by 69 publications

References 44 publications

Improved Reliability and Mechanical Performance of Ag Microalloyed Sn58Bi Solder Alloys

Improved Reliability and Mechanical Performance of Ag Microalloyed Sn58Bi Solder Alloys

Improved Reliability and Mechanical Performance of Sn58Bi Solder Alloys

A Computational Thermodynamics-Assisted Development of Sn-Bi-In-Ga Quaternary Alloys as Low-Temperature Pb-Free Solders

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Improvement in the mechanical properties of eutectic Sn58Bi alloy by 0.5 and 1 wt% Zn addition before and after thermal aging