Intermetallic evolution between Sn-3.5Ag-1.0Cu-xZn lead free solder and copper substrate under long time thermal aging (x: 0, 0.1, 0.4, 0.7) (original) (raw)
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Intermetallic Evolution of Sn-3.5 Ag-1.0 Cu-0.1 Zn/Cu Interface under Thermal Aging
2013
Due to environmental concerns, lead-free solders were introduced in replacing the leadbased solders in microelectronics devices technology. Although there are many lead-free solder available, the SnAg -Cu is considered the best choice. But the solder has its draw backs in terms of melting temperature and intermetallic formations. To improve the solder, a fourth element Zn was added into the solder. The new composite solders were synthesized via powder metallurgy route. This research studies the effect of 0.1wt% Zn addition on the hardness and intermetallic formation on Cu substrate. For the hardness results, the micro Vickers values were reported. For intermetallic, the solders were melted at 250 o C and aged at 150 o C until 400 hours. The microhardness value for Zn based composites solder shows higher micro Vickers hardness compared to un-doped counterparts. The phases formed and its growth was studied under SEM and by energy dispensive x-ray (EDX). The SEM results show the presence of Cu 6 Sn 5 and Cu 3 Sn intermetallics and the Cu 5 Zn 8 intermetallic was not detected. The addition of 0.1wt% Zn has retarded the growth of the Cu 3 Sn intermetallic but not the total intermetallic thickness.
The effect of adding Zn into the Sn–Ag–Cu solder on the intermetallic growth rate
Journal of Materials Science: Materials in Electronics, 2014
Due to toxicity of lead in the commercial solder, lead-free solders were proposed. Among the potential leadfree solders, the SnAg -Cu solders were considered as a potential replacement. To further improve the solder properties, a fourth element was added into the SnAg -Cu solder. The present study investigates the effect of different weight percentage of Zn (up to 0.7 wt%) into the Sn-3.5Ag-1.0Cu solder on intermetallic and growth rate (k) after long time thermal aging. The solders were prepared using powder metallurgy method and X-ray diffraction analysis shows that there were Cu 6 Sn 5 , Cu 3 Sn, CuZn and Ag 3 Sn phases present after solder preparation. The solders were reacted with Cu substrate at 250°C for 1 min and aged at 150°C until 1,000 h. The morphology of the intermetallic was observed under scanning electron microscope and the elemental distribution was confirmed by energy dispersive X-ray. Intermetallic thickness and growth kinetic result show that the additions of 0.4 % zinc is sufficient in retarding the Cu 6 Sn 5 and Cu 3 Sn intermetallic growth.
The Sn-3.5 Ag-1.0 Cu-0.1 Zn/Cu Intermetallic Interface under Thermal Aging
Due to environmental concerns, lead-free solders were introduced to replace the lead-based solders in microelectronics devices technology. Although there were many lead-free solder available, the Sn-Ag-Cu was considered as the best choice. But the solder has its draw backs in terms of melting temperature and intermetallic formations. To improve the solder, a fourth element Zn was added into the solder and was synthesized via powder metallurgy route. This research studies the effect of 0.1wt% Zn addition on the mechanical properties and intermetallic formation on Cu substrate. For the mechanical test, the Vickers hardness (Hν), yield strength (σy) and ultimate tensile strength (σUTS) were reported. The mechanical test for Zn based composites solder shows better properties compared to un-doped counterparts. For intermetallic, the solders were melted at 250 o C and aged at 150 o C until 400 hours. The phases formed and its growth was studied under SEM and by energy dispersive x-ray (EDX). The addition of Zinc has improved the mechanical properties of Sn-Ag-Cu solder, while the SEM results show the presence of Cu6Sn5 and Cu3Sn intermetallics. The addition of 0.1wt% Zn has retarded the growth of the Cu3Sn intermetallic but not the total intermetallic thickness.
Universiti Teknologi MARA, Perlis, 2012
Due to environmental concerns, lead-free solders were introduced to replace the lead-based solders in microelectronics devices technology. Although there were many lead-free solder available, the SnAg -Cu was considered as the best choice. But the solder has its draw backs in terms of melting temperature and intermetallic formations. To improve the solder, a fourth element Zn was added into the solder and was synthesized via powder metallurgy route. This research studies the effect of 0.1wt% Zn addition on the mechanical properties and intermetallic formation on Cu substrate. For the mechanical test, the Vickers hardness (Hν), yield strength (σ y) and ultimate tensile strength (σ UTS) were reported. The mechanical test for Zn based composites solder shows better properties compared to un-doped counterparts. For intermetallic, the solders were melted at 250 o C and aged at 150 o C until 400 hours. The phases formed and its growth was studied under SEM and by energy dispersive x-ray (EDX). The addition of Zinc has improved the mechanical properties of SnAg -Cu solder, while the SEM results show the presence of Cu 6 Sn 5 and Cu 3 Sn intermetallics. The addition of 0.1wt% Zn has retarded the growth of the Cu3Sn intermetallic but not the total intermetallic thickness.
2016
The need for replacing lead based solder has received great attention among researchers because of their toxicity. The Sn-Ag-Cu family is the most promising candidate. However, these solder systems need better improvement in terms of controlling their intermetallic formation, growth rate and also their mechanical properties. In this study, the Sn-3.5Ag-l.0Cu solder was studied and three different amounts of Zn were added into the solder system. The solder was prepared using powder metallurgy method. It was characterized for their melting temperature, hardness and density. For intermetallic study, the solder was melted at 250°C on a Cu substrate and placed in an oven at 150°C until 1000 h. After the aging process, the solder joint was cross-sectioned and analysed under a Scanning Electron Microscope and Energy Dispersive X-ray. The thickness of Cu₆Sn₅ and Cu₃ Sn intermetallics were measured using image J software and their growths kinetic were calculated. The shear joint specimen was...
Influence of Bi on microstructures evolution and mechanical properties in Sn–Ag–Cu lead-free solder
Journal of Alloys and Compounds, 2004
Sn-Ag-Cu-Bi solders, which have high quality and performance that can meet the requirement of electronic packaging, have been investigated in this paper. The research was focused on the influence of aging on the microstructural evolution and mechanical properties in Sn-3Ag-0.5Cu-xBi (x = 0-3 wt.%) solders. The effect of Bi was discussed based on the experimental results. The experimental results indicated that the addition of Bi enhanced the tensile strength of the solders but decreased their elongation. After aging treatment, Sn-3Ag-0.5Cu solder showed significant change in strength and elongation which resulted from the obvious coarsening of Ag 3 Sn and Cu 6 Sn 5 intermetallics. As for Bi-bearing solders, Bi precipitation in Sn matrix was only observed in Sn-3Ag-0.5Cu-3Bi solder after being aged at 120 • C for 100 h, while all the Bi-bearing solders exhibited relatively stable mechanical properties with aging time which can be attributed to the strengthening effect of Bi from solid solution strengthening to precipitating strengthening.
Materials Science and Engineering: A, 2010
In the present study, the effects of separate and dual addition of small amount of Ag and Cu on the microstructure and mechanical properties of the eutectic Sn-9Zn solder alloy were investigated. Results indicate that alloying of Ag and/or Cu resulted in refine the coarse needle-like Zn-rich phase and formation of intermetallic compounds (IMCs) with the eutectic solder. Single addition of Ag led to formation of AgZn, Ag 5 Zn 8 and -AgZn 3 IMCs, which results in significant increase in both ultimate tensile strength (UTS) and ductility, while, the flower shaped and rod shaped Cu 6 Sn 5, ␥-Cu 5 Zn 8 and -CuZn 5 IMCs produced by Cu alloying, results in small increase in UTS and ductility. The dual addition of Ag and Cu suppressed the appearance of Ag 5 Zn 8 IMCs due to the competition for Zn between Cu and Ag, which results in slight decrease in UTS and ductility of Sn-9Zn-1.5Ag solder. Worthy of notice is that all alloys demonstrated an increase in both UTS and yield stress with increasing strain rate and/or decreasing testing temperature, indicating that the tensile behavior of the four alloys often exhibits a strain rate and temperature dependence.
A study on the reaction between Cu and Sn3.5Ag solder doped with small amounts of Ni
Journal of Electronic Materials, 2003
The reaction between Cu and the Sn-Ag solders doped with different amounts of Ni is studied. Four different solders with the Ag concentration fixed at 3.5 wt.% and Ni concentrations varied between 0.0 wt.% and 1.0 wt.% are used. In contrast to the reaction between Ni and the Sn-Ag solders doped with different amounts of Cu, the type of intermetallic compound formed does not depend on the Ni concentration. The compound Cu 6 Sn 5 forms for all the Ni concentrations used. For the Ni-doped solders, the Cu 6 Sn 5 phase contains a small amount of Ni. The compound Cu 3 Sn appears subsequently between Cu 6 Sn 5 and Cu as the reaction time increases. The addition of Ni has the effect of substantially increasing the amount of intermetallic compound at the interface. The addition of Ni also produces two distinct Cu 6 Sn 5 regions at the interface. The outer region contains more Ni, and the inner region contains less Ni. This study also finds that, during solid-state aging, the growth of Cu 3 Sn becomes slower when Ni is added to the solder. The findings of this study are rationalized using the Cu-Ni-Sn isotherm.
Solderability of Sn–9Zn–0.5Ag–1In lead-free solder on Cu substrate
Journal of Alloys and Compounds, 2006
The thermal properties, microstructure corrosion and oxidation resistance of the Sn-9Zn-0.5Ag-1In lead-free solder have been investigated by differential scanning calorimetry, X-ray diffractometry, scanning electron microscopy, energy dispersive spectrometry, potentiostat and thermogravimetry. The Sn-9Zn-0.5Ag-1In solder alloy has a near-eutectic composition, it melts at 187.6 • C and the heat of fusion is determined as 71.3 J/g. The Sn-9Zn-0.5Ag-1In solder alloy with a corrosion potential of −1.09 V SCE and a current density of 9.90 × 10 −2 A/cm 2 , shows a better corrosion resistance than that of the Sn-9Zn solder alloy. From the thermogravimetry analysis, the weight gain ratio of the Sn-9Zn solder alloy appears a parabolic relationship at 150 • C. The initial oxidation behavior of the Sn-9Zn-0.5Ag and Sn-9Zn-0.5Ag-1In solder alloys also shows a parabolic relationship but the weight gain ratio of them appears a negative linear one after aging at 150 • C for 2.5 and 5 h, respectively.