Ternary Sn Research Articles

Ternary Sn–Co–C Li-ion battery electrode material prepared by high energy ball milling

The recent announcement of the launch in the market of a new type of lithium-ion battery has instilled new life in the R&D of innovative electrode materials and, in particular on multi-component, tin-based, nanostructured lithium metal storage anodes. Following this trend, we have synthesized by high energy ball milling a Sn–Co–C ternary compound of composition supposedly similar to that used in the new commercial battery. We have tested this material as an electrode in a single lithium cells, as well as in an original, complete lithium-ion battery configuration. The results demonstrate the promising feature of this compound as innovative, high-capacity lithium-ion electrode.

Phase stability in Cu–Zn-based ternary alloys with elements of column 14

By adding small amounts of ternary elements Ge, Si or Sn, it is possible to raise the martensitic transformation temperature M S of binary B2 ordered Cu–Zn towards room temperature. Several poly and single crystal ternary alloys have been studied using resistivity and calorimetric measurements, tensile experiments and optical observations. The influence of the composition and thermomechanical pretreatment on the martensitic transformation has been analyzed. It is shown that the increase in the transformation temperature at a constant electron concentration favors competing decomposition mechanisms.

Thermochemical properties of ternary Si-Ni-Al liquid alloys

Partial (for aluminum) and integral mixing enthalpies of ternary Si-Ni-Al liquid alloys are examined by high-temperature calorimetry under isoperibolic conditions at 1770 ± 5 K. Alloys of five radial sections with a constant ratio of silicon-to-nickel mole fractions (xSi/xNi = 0.85/0.15; 0.7/0.3; 0.5/0.5; 0.3/0.7, and 0.15/0.85) within the interval compositions to aluminum mole fraction xAl ∼ 0.6 are studied. The mixing enthalpies of Si-Ni-Al alloys are characterized by great exothermal values. Exothermal partial enthalpies of aluminum mixing increase at infinite dilution $$\Delta _m \bar H^\infty Al$$ with increasing nickel concentration in starting binary alloys ( $$\Delta _m \bar H^\infty Al$$ reaches −17.0 ± 3.3 kJ/mole for section with xSi/xNi = 0.85/0.15 and −119.0 ± 11.2 kJ/mole for xSi/xNi = 0.15/0.85). An analysis of alloy-formation energy parameters in the ternary Si-Ni-Al system indicates that the interaction of the components in the bounded binary Si-Ni and Ni-Al systems greatly contributes to ΔmH, the effect of the former prevailing. The thermochemical properties of ternary alloys and of Ge-Ni-Al melts and simulated mixing enthalpies of ternary Sn (C)-Ni-Al liquid alloys are compared.

Pressure-Induced Crystallization and Characterization of the Tin Borate β-SnB4O7

In the last years, several investigations were performed in the ternary system Sn−B−O as a simplified variant of the tin-based amorphous composite oxide (TCO), a material in use as negative electrode of lithium-ion rechargeable batteries. All compounds in this system are glasses, so the synthesis of crystalline approximands for a more detailed structural investigation would be favorable. The use of high-pressure/high-temperature conditions (7.5 GPa and 1100 °C; Walker-type multianvil apparatus) led to the synthesis of the first crystalline tin borate β-SnB4O7. The single-crystal structure determination of β-SnB4O7 showed Pmn21, a = 1086.4(2) pm, b = 444.80(9) pm, c = 423.96(8) pm, Z = 2, R1 = 0.0155, and wR2 = 0.0324 (all data). In contrast to the isotypic phases MB4O7 (M = Sr, Pb, Eu, β-Ca, and β-Hg), the position of the tin atom in β-SnB4O7 is influenced by the existence of a stereochemically active lone pair. Furthermore, we report on thermoanalytical aspects (DTA-TG and temperature-resolved in situ po...

Electrochemical co-deposition of ternary Sn–Bi–Cu films for solder bumping applications

This paper reports the co-deposition of Sn–Bi–Cu films using stannic salt bath which has good stability for up to a week. The effect of current density and bath stirring on the film composition and microstructure has been studied. The deposited films are rich in the more noble metal Bi at current densities up to 5 mA cm−2 but stabilize to about 49 wt. % Bi, 47 wt. % Sn and 4 wt. % Cu at 10 mA cm−2 and beyond, indicating the effect of limiting current density. There is improvement in the microstructure with stirring or aeration, but the film composition reverts to the Bi rich state, with close to 90 wt. % Bi for deposition at 5 mA cm−2. This is attributed to the dispersion of Sn2+ ions generated at the cathode during the two-step reduction of Sn4+ ions, due to stirring. The bath is suitable for near eutectic compositions of Sn–Bi with <5 wt. % Cu content.

Pb-Free solders: Part II. Application of ADAMIS database in modeling of Sn−Ag−Cu alloys with Bi additions

The ADAMIS database was used for calculation of the surface tension of the quaternary Sn−Ag−Cu−Bi liquid alloys by Butler's model. The resultant data were compared with those from the maximum bubble pressure measurements from Part I. The same thermodynamic database was next applied for the calculation of various phase equilibria. It was established that the Bi addition to the ternary Sn−Ag−Cu alloys (Sn-2.6Ag-0.46Cu and Sn-3.13Ag-0.74Cu in at.%; Sn-2.56Ag-0.26 Cu and Sn-2.86Ag-O.40Cu in mass%) causes lowering of the melting temperature and the surface tension to make the tested alloys closer to, traditional Sn−Pb solders. The simulation of the solidification by Scheil's model showed that the alloys with the higher Bi concentration are characterized by the lifting-off failure due to the segregation of Bi at the solder/substrate boundary. Thus, in modeling of new Pb-free solders, a compromise among various properties should be taken into consideration.

Phase equilibria of the Sn–Zn–Cu ternary system

Phase equilibria of the Sn–Zn–Cu ternary system are of fundamental importance for the industrial applications of Sn–Zn-based solders. However, there is a lack of experimental information as regards the Sn–Zn–Cu phase equilibria. In this study, the isothermal sections of the Sn–Zn–Cu phase equilibria at 250, 230, and 210 °C were experimentally determined. In addition, the 180 °C isothermal section is proposed without experimental verification. Ternary Sn–Zn–Cu alloys were prepared and equilibrated at these three temperatures. The equilibrium phases in the annealed alloys were determined. No ternary compound was found, and no noticeable Sn solubilities were observed in the ε-CuZn 5 phase. Isothermal sections at these three temperatures were constructed based on the ternary experimental results and the phase diagrams of the three constituent binary systems. In contrast to previous calculated results, it was observed that the molten Sn has tie-lines with the η-Cu 6Sn 5 phase and all the binary Cu–Zn compounds at 250 and 230 °C.

Phase Diagram of the Sn—Zn—Ti System.

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Phase diagram of the Sn–Zn–Ti system

Equilibrated Sn–Zn–Ti alloys and (Sn + Zn)/α-Ti diffusion couples have been studied by scanning electron microscopy, metallography, and differential scanning calorimetry. For the first time an isothermal section, at 600 °C, of the ternary Sn–Zn–Ti system has been constructed. A previously unknown ternary phase with approximate formula Ti 3Sn 2Zn 6 (probable homogeneity interval in the range Ti 5Sn 4Zn 11 to Ti 5Sn 3Zn 12) has been found. The solubility ranges of the titanium based solid solutions and the intermetallic phases have been looked for. As far as we could detect and in agreement with theoretical considerations, zinc dissolves more in Ti–Sn phases than tin into Ti–Zn compounds. Titanium additions of 3 and 4 at.% Ti do not influence significantly the Sn–Zn eutectic temperature. The experimentally determined melting enthalpies of the nearly eutectic alloys have values around 100 J g −1.

Phase Equilibria in the Sn-Rich Corner of the Sn–Cu–Ni Ternary Alloy System at 240 °C

The interfacial reactions between solders and under bump metallization (UBM) have been of great interest recently in flip chip technology. Intermetallic compounds (IMCs), i.e., (Cu,Ni)6Sn5 and (Ni,Cu)3Sn4, usually formed between solders and UBM. To fully understand the interfacial reactions and phase transformation phenomenon, a suitable phase diagram concerning solders, IMCs, and UBM materials is required. In particular, a Sn-rich phase region in the Sn–Cu–Ni ternary diagram is very critical in determining the concentration tendency of x and y values in (Ni1−x,Cux)3Sn4 and (Cu1−y,Niy)6Sn5 compounds. In this study, ternary Sn–Cu–Ni alloys were prepared and annealed at 240 °C. Three equilibrium phases, Sn, Ni3Sn4, and Cu6Sn5, were identified by x-ray diffraction analysis and also showed in backscattered electron imaging. Using electron probe microanalysis quantitative analysis, three acme compositions of the ternary region in the Sn–Cu–Ni isotherm near the Sn-rich corner were determined as 98.5 at.% Sn, (Ni0.80, Cu0.20)3Sn4 and (Cu0.59,Ni0.41)6Sn5. In addition, the solubility of Cu and Ni in (Ni,Cu)3Sn4 and (Cu,Ni)6Sn5 compounds was evaluated. Finally, the isothermal section of the ternary Sn–Cu–Ni system at 240 °C was proposed on the basis of experimental results in this study.

A study of the thin film on the surface of Sn–3.5Ag/Sn–3.5Ag–2.0Cu lead-free alloy

The ternary lead-free solder alloy Sn–Ag–Cu has been considered as a potential alternative to lead–tin alloys, but oxidation of the solders often occurs at the injection-ball, even during reflow. This study investigates the characteristics of the solidification thin film of both the Sn–3.5Ag alloy and the Sn–3.5Ag–2.0Cu alloy to discuss and clarify the mechanism acting on the oxidative thin film. The results indicate that the solidification surface thin film of the Sn–3.5Ag–(2.0Cu) is mostly composed of SnO phase and SnO 2 phase. The concentration of Sn 4+ is higher than that of Sn 2+ in the film. The concentration of Sn 2+ and O increases at sites near the solidified thin film. On the surface thin film, increasing the Cu content can decrease the diffusion distance of Sn 2+ and repress the growth of SnO x phase. The thickness of the oxidative thin film of Sn–3.5Ag–2.0Cu alloy was 1060 ± 85 nm and part of the oxidative thin film was tetragonal SnO 2.

Phase Equilibria in the Dy—Cu—Sn Ternary System.

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Effect of 9 wt.% in addition to Sn3.5Ag0.5Cu solder on the interfacial reaction with the Au/NiP metallization on Cu pads

Sn-based lead-free solders have a high melting temperature, which often cause excessive interfacial reactions at the interface. A small amount of In is added to reduce the melting temperature and to change the intermetallic compound (IMC) phases. Sn3.5Ag0.5Cu and Sn3.5Ag0.5Cu9In lead-free solder alloys have been used to identify its interfacial reactions with 2-metal layer flexible substrates. In this paper we investigate the effect of 9 at.% In addition to Sn3.5Ag0.5Cu solder during extended reflow. During reflow, Au diffuses rapidly in the molten Sn Ag Cu solder and forms AuSn 4 IMC but in the case of In-containing solder, In Sn Au IMCs form and are uniformly distributed in the solder. Some In Sn Au IMCs have been entrapped in the Sn Cu Ni In quaternary intermetallic compounds (QIMCs) due to lower diffusion rate of Au in the In-containing solder. Initially Sn Cu Ni ternary intermetallic compounds (TIMCs) and Sn Cu Ni In QIMCs form at the interface, which have higher growth rate and consume more of the NiP layer. Low-Cu QIMCs are found in the In-containing solder after 30 min reflow which are more stable in the P-rich Ni layer and significantly reduce the dissolution rate of the NiP layer. The spalling of Sn Cu Ni TIMCs in the Sn Ag Cu solder increases the diffusion rate of Sn atoms and as a consequence both the TIMCs growth rate and dissolution rate of the NiP layer also increases. In-containing solder have lower growth rate of the QIMCs and lower dissolution rate of the NiP layer than the Sn Ag Cu solder. Consumption of the NiP layer can be reduced by adding In, because of the formation of QIMCs at the interface, QIMCs are stable and are well adhering to the P-rich Ni layer during reflow.

Solidification of ternary eutectic and near eutectic alloys in the Ag – Cu – Sn system

The techniques for quenching samples during freezing, slow unidirectional solidification and differential scanning calorimetry were used to evaluate the freezing characteristics of eutectic and near eutectic ternary Sn rich Ag – Cu – Sn alloys. The ternary eutectic temperature was verified as 217·2±0·4°C and composition as 3·5 wt-%Ag, 0·9 wt-%Cu, 96·5 wt-%Sn. The ternary eutectic was observed to be of the faceted (Ag3Sn) faceted (Cu6Sn5) nonfaceted (Sn) type. The Ag3Sn phase forms a broken lamellar microstructure while the Cu6Sn5 phase forms a fibrous microstructure in which the fibres become 'hollow' hexagonal prisms (filled by Sn) at very low growth rates. The volume fraction occupied by the two compound phases was measured as 5·5±0·5 vol.-% and calculated as 5·63 vol.-%. It was observed that the compound phases are poor nucleation catalysts for Sn. The presence of faceting phases results in the formation of a skewed coupled zone, causing formation of primary Sn dendrites on freezing of a melt even of eutectic composition. When fractured, both compound phases showed brittle behaviour.

Liquidus projection of the ternary Ag–Sn–Ni system

The liquidus projection of the ternary Sn–Ag–Ni system at the Sn-rich side was determined experimentally. No ternary compound was found, and the ζ–Ag4Sn, Ag3Sn, and Sn existed as the primary solidification phases only in very small compositional portions of the ternary Sn–Ag–Ni system. In more than half of the compositional regime of the ternary system, the Ni3Sn2 phase was the primary solidification phase. The differential thermal analysis technique was used to determine the reaction temperatures and solidification sequences of various Sn-rich Sn–Ag–Ni alloys. Three invariant reactions were found: L = Sn + Ni3Sn4 + Ag3Sn, L + ζ–Ag4Sn = Ni3Sn4 + Ag3Sn and L + Ni3Sn2 = ζ–Ag4Sn + Ni3Sn4. Their reaction temperatures have been determined to be 219, 488, and 516.5 °C, respectively.

Improvement on the microstructure stability, mechanical and wetting properties of Sn–Ag–Cu lead-free solder with the addition of rare earth elements

Ternary lead-free solder alloys Sn–Ag–Cu were considered as the potential alternatives to lead–tin alloys comparing with other solders. In this paper, microstructure and mechanical properties of Sn–2.5Ag–0.7Cu, Sn–3.5Ag–0.7Cu, Sn–3.5Ag–0.7Cu–0.1RE, and Sn–3.5Ag–0.7Cu–0.25RE alloys were researched. Coarse β-Sn grains were formed in Sn–2.5Ag–0.7Cu and Sn–3.5Ag–0.7Cu alloys and bulky Ag 3Sn intermetallics were found in Sn–3.5Ag–0.7Cu alloy. With the addition of trace rare earth (RE) elements the coarse β-Sn grains were refrained, at the same time, Cu 6Sn 5 and Ag 3Sn intermetallics were finer according to the adsorption affection of the active rare earth elements. Due to the fine and uniform microstructure, the tensile strength and elongation were improved. In addition, the wetting properties were also enhanced. All these results indicated that adding trace rare earth elements was an efficient way to develop new solders.

Analyses of interfacial reactions at different levels of interconnection

Continuous miniaturization of electronic devices increases the importance of the understanding and control of the physical and chemical compatibility between dissimilar materials in order to design and fabricate reliable products. Thermodynamic and kinetic modelling together with careful experimental work is of great help for understanding and controlling interdiffusion and chemical reactions in interconnection structures. The approach provides useful information on the stabilities of phases (microstructures), driving forces for chemical reactions and growth rates of reaction products occurring in interconnections or thin film structures during processing, testing and in long-term use of electronic devices. In this paper two examples of the approach outlined above are presented. Firstly, the case of TaC diffusion barrier between Cu and Si at the IC-interconnection level is discussed. Complex reactions occur in this system especially when oxygen is present as an impurity. Evaluated Si–Ta–Cu, Ta–C–O and Si–Ta–C ternary stable as well as metastable phase diagrams are used together with the calculated activity diagrams and detailed transmission electron microscopy (TEM) results to rationalize the formation of the observed microstructure after extensive reactions. Secondly, reactions occurring between the Ni(P)/Au printed wiring board (PWB) surface finish and copper containing lead-free solders at the board level are presented. To understand the formation (Cu,Ni) 6Sn 5 instead of the expected Ni 3Sn 4 during soldering the ternary Sn–Cu–Ni phase diagram is used. The influence of the subsequent solid state annealing and the related mass-supply effects on the stability of the microstructure are also discussed.

Solvothermal preparation and thermoelectric properties of ternary Sn–Bi–Te alloy

Ternary Sn–Bi–Te nanoparticles were directly synthesized by a solvothermal process based on the reaction between BiCl3, SnCl2, Te, and KBH4 in N,N-dimethylformamide at 100–180 °C. KBH4 was used as a reducing agent. The microstructure of bulk sample was characterized by XRD and SEM. The sample shows p-type semiconducting behavior with disordered layered structure. The electrical resistivity, Seebeck coefficient, and thermal conductivity of the samples were measured from room temperature to about 700 K. The samples show a maximum Seebeck coefficient of 105 μV/K around 414 K and maximum thermal conductivity of 0.52 W/mK around 298 K. (© 2003 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Ag3Sn plate formation in the solidification of near ternary eutectic Sn–Ag–Cu alloys

Near-ternary eutectic Sn–Ag–Cu alloys are leading candidates for Pb-free solders. These alloys have three solid phases: β–Sn, Ag3Sn, and Cu6Sn5. Starting from the fully liquid state in solidifying near-eutectic Sn–Ag–Cu alloys, the equilibrium eutectic transformation is kinetically inhibited. The Ag3Sn phase nucleates with minimal undercooling, but the β–Sn phase requires a typical undercooling of 15 to 30 °C for nucleation. Because of this disparity in the required undercooling for nucleation, large, platelike Ag3Sn structures can grow rapidly within the liquid phase, before the final solidification of the solder joints. At lower cooling rates, the large Ag3Sn plates can subtend the entire cross section of solder joints and can significantly influence the mechanical deformation behavior of the solder joints under thermomechanical fatigue conditions. In this paper, it is demonstrated that the Ag3Sn plate formation can be inhibited, an important factor in assuring the reliability of solder joints composed of these alloys.

Microstructure evolution in Sn–Bi and Sn–Bi–Cu solder joints under thermal aging

Abstract Binary eutectic Sn–Bi and ternary Sn–Bi–Cu alloys were fabricated and soldered to conductor metallized substrates to study the interfacial morphology and microstructural evolution of the joints under thermal aging. Different types of intermetallic compound (IMC), such as Cu 6 Sn 5 , (Cu, Ni) 6 Sn 5 and Ag 3 Sn, are observed among various metallized substrates including Cu/FR4, Ni/Cu/FR4, Cu/Al 2 O 3 and Pt–Ag/Al 2 O 3 . Three major effects of aging on the microstructure of the solder joints are observed. First, the coarsening rate of the Bi-rich phase in the solder joint under thermal aging at 120°C is reduced by adding 1 wt.% Cu to the 42Sn–58Bi solder. Second, the Ag 3 Sn IMC forms planar layer at the solder/PtAg interface, while the Cu 6 Sn 5 intermetallic grows as scallop-like grains into the solder at the Cu/solder interface. Third, the growth of Ag 3 Sn intermetallic in the SnBi–1Cu/PtAg solder joint is slower than that in the 42Sn–58Bi/PtAg joint after thermal aging at 120°C.