Thermodynamic Descriptions for the Cd-Te,Pb-Te,Cd-Pb and Cd-Pb-Te Systems

The thermodynamic behaviors of the Cd-Te, Pb-Te, Cd-Pb and Cd-Pb-Te systems are critically analyzed in this work by means of the calculation of phase diagrams (CALPHAD) method. The liquid phases containing Te are described by the associated solution model, which is capable of dealing with V-shaped curves of mixing enthalpies in solution phases, sharp maxima of liquidus curves in phase diagrams, and abrupt changes in activity plots. The binary compounds, CdTe and PbTe, are considered to be stoichiometric in the two binary systems, but they form a line compound described by (Cd,Pb)₁(Te)₁ in the ternary system. The fcc phase, in which only Cd and Pb elements are present, is treated with the substitutional solution model. The experimental data available in the literature are extensively assessed, from which the thermodynamic parameters necessary for each phase are obtained. Various calculated phase equilibria and thermodynamic properties are compared with the experimental data. The excellent agreement indicates that this work contributes to the study of phase stabilities in the Cd-Pb-Te system.     

A thermodynamic study of the phase equilibria in the Bi-Sn-Sb system

A thermodynamic study has been carried out on the Bi-Sn-Sb ternary alloy system. The Gibbs energy of individual phases has been approximated using the regular solution, two-sublattice model, and the thermodynamic parameters for each phase have been evaluated using the available experimental information on phase boundaries and other related thermodynamic properties. Thermal analysis experiments have also been performed on several ternary alloys to re-examine and augment the available ternary experimental data. The set of evaluated thermodynamic parameters arrived at in this study, enables reproducible calculations of the liquidus and solidus temperatures and vertical section diagrams quite satisfactorily.     

A thermodynamic study of phase equilibria in the Au-Sb-Sn solder system

To design and develop high-temperature solder alloys, the thermodynamic calculations of phase equilibria have been performed on the binary Au-Sb and ternary Au-Sb-Sn systems over the entire composition range. The Gibbs free energy of individual phases has been approximated using a subregular-solution model, and the thermodynamic parameters for each phase have been evaluated using available experimental information on phase boundaries and other related thermodynamic properties. The calculated phase diagrams and thermodynamic quantities of the Au-Sb binary system show good agreement with experimental data, and the liquidus projection and the vertical sections in the Au-Sb-Sn ternary system are well reproduced using assessed thermodynamic parameters derived in this work.     

Thermodynamic assessment of the Sn-Co lead-free solder system

The Sn-Co-Cu eutectic alloy can be a less expensive alternative for the Sn-Ag-Cu alloy. In order to find the eutectic solder composition of the Sn-Co-Cu system, the Sn-Co binary system has been thoroughly assessed with the calculation of phase diagram (CALPHAD) method. The liquid phase, the FCC and HCP Co-rich solid solution, and the BCT Sn-rich solid solution have been described by the Redlich-Kister model. The Hillert-Jarl-Inden model has been used to describe the magnetic contributions to Gibbs energy in FCC and HCP. The CoSn₂, CoSn, Co₃Sn_{2_}β, and Co₃Sn_{2_}α phases have been treated as stoichiometric phases. A series of thermodynamic parameters have been obtained. The calculated phase diagram and thermodynamic properties are in good agreement with the experimental data. The obtained thermodynamic data was used to extrapolate the ternary Sn-Co-Cu phase diagram. The composition of the Sn-rich eutectic point of the Sn-Co-Cu system was found to be 224°C, 0.4% Co, and 0.7% Cu.     

Thermodynamic Assessments of the Ag-Ni Binary and Ag-Cu-Ni Ternary Systems

The phase diagram of the Ag-Ni binary system has been evaluated by using the calculation of phase diagrams (CALPHAD) method based on experimental data of the phase equilibria and thermodynamic properties. Gibbs free energies of the liquid and fcc phases were described by the subregular solution model with the Redlich–Kister equation. On the basis of the thermodynamic parameters of the Ag-Ni, Ag-Cu, and Cu-Ni systems, and experimental information of the phase equilibria in the Ag-Cu-Ni system, the thermodynamic assessment in the Ag-Cu-Ni system was carried out. The calculated results in both the Ag-Ni and Ag-Cu-Ni systems are in reasonable agreement with experimental data.     

Experimental determination and thermodynamic calculation of the phase equilibria and surface tension in the Sn-Ag-In system

The phase equilibria of the Sn-Ag-In system were investigated by means of differential scanning calorimetry (DSC) and metallography. The isothermal sections at 180–600°C, as well as some vertical sections, were determined. Thermodynamic assessment of this system was also carried out based on the experimental data of thermodynamic properties and phase equilibria using the calculation of phase diagram (CALPHAD) method, in which the Gibbs energies of the liquid, fcc, and hcp phases are described by the subregular solution model, and those of compounds are represented by the sublattice model. The thermodynamic parameters for describing the phase equilibria were optimized, and reasonable agreement between the calculated and experimental results was obtained. The maximum bubble-pressure method and dilatometric method have been used in measurements of the surface tension and density of the binary In-Sn and ternary (Sn-3.8Ag)_eut + In (5 at.% and 10 at.%) liquid alloys, respectively. The experiments were performed in the temperature range from 160–930°C. The experimental data of the surface tension were compared with those obtained by the thermodynamic calculation of Butler’s model.     

Studies of the Ag-In phase diagram and surface tension measurements

The phase boundaries of the Ag-In binary system were determined by the diffusion couple method, differential scanning calorimetry (DSC) and metallographic techniques. The results show that the region of the (hcp) phase is narrower than that reported previously. Thermodynamic calculation of the Ag-In system is presented by taking into account the experimental results obtained by the present and previous works, including the data on the phase equilibria and thermochemical properties. The Gibbs energies of liquid and solid solution phases are described on the basis of the sub-regular solution model, and that of the intermetallic compounds are based on the two-sublattices model. A consistent set of thermodynamic parameters has been optimized for describing the Gibbs energy of each phase, which leads to a good fit between calculated and experimental results. The maximum bubble pressure method has been used to measure the surface tension and densities of liquid In, Ag, and five binary alloys in the temperature range from 227°C to about 1170°C. ON the basis of the thermodynamic parameters of the liquid phase obtained by the present optimization, the surface tensions are calculated using Butler’s model. It is shown that the calculated values of the surface tensions are in fair agreement with the experimental data.     

Experimental investigation and thermodynamic calculation of phase equilibria in the Sn-Au-Ni system

The phase equilibria of the Sn-Au-Ni system, including six isothermal section diagrams in the Sn-rich portion at 200–600°C, as well as three vertical sections at Au:Ni=1:1, 50at.%Sn, and 40at.%Sn, were investigated by means of differential scanning calorimetry (DSC), x-ray diffraction, and metallography. The experimental results indicated that (1) there exists a ternary compound Sn₄AuNi₂ that is stable up to about 400°C, (2) there are larger solubilities of Au in the Ni₃Sn₂ phase in the Sn-Ni system and Ni in the SnAu phase in the Sn-Au system, and (3) there is the two-phase equilibrium between Sn₂Ni₃ and SnAu compounds below 400°C, rather than the continuous phase region from the Sn₂Ni₃ to the SnAu phases reported previously. Thermodynamic assessment of the Sn-Au-Ni system was also carried out by using the calculation of phase diagrams (CALPHAD) method, in which the Gibbs energies of the liquid, fcc, and hcp phases are described by the subregular solution model and that of compounds, including a ternary compound, are represented by the sublattice model. The thermodynamic parameters for describing each phase were optimized and good agreement between the calculated and experimental results was obtained.     

Thermodynamic Descriptions and Phase Diagrams for Pb-S and Bi-S Binary Systems

In this work, thermodynamic optimization of the Pb-S and Bi-S binary systems has been performed using the calculation of phase diagrams approach. The Gibbs free energies of the liquid phases in the two binary systems are treated with the associated solution model. The two intermediate compounds, i.e., PbS and Bi₂S₃, are modeled as stoichiometric phases. A set of self-consistent thermodynamic parameters for the Pb-S and Bi-S binary systems has been obtained by simultaneous optimization of the available thermodynamic and phase equilibria data, the results of which lead to good agreement between the calculated and experimentally measured data.     

Phase equilibria and thermodynamic properties of Sn-Ag based Pb-free solder alloys

We have recently developed a thermodynamic database for micro-soldering alloys, alloy database for micro-solders (ADAMIS). ADAMIS which consists of the elements Ag, Bi, Cu, In, Pb, Sb, Sn, and Zn has been constructed by the calculation of phase diagrams (CALPHAD) method. The thermodynamic parameters for describing the Gibbs energy of the liquid and solid phases have been evaluated by optimizing the experimental data on phase boundaries and thermo-chemical properties. In this paper, the phase equilibria and the related thermodynamic properties pertaining to the Sn-Ag-X (X=Bi, In, Cu, and Zn) alloys are examined using ADAMIS. Typical examples of the isothermal and vertical section phase diagrams, liquidus surface, etc. for these promising lead-free solders are presented. In addition, ADAMIS is also applied to calculate the nonequilibrium solidification process using the Scheil model.     

Stability of metal/GaAs-lnterfaces: A phase diagram survey

Calculated phase diagrams of ternary Ga-As-metal systems for the metals Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Re, Os, Rh, Ir, Ni, Pd, Pt, Cu, Ag and Au are presented. The predictive calculations are based on the following simplifications: Ternary phases and solid solubilities are disregarded and the Gibbs energy of formation of binary compounds is estimated by the enthalpy of formation and calculated from Miedema’s model. The predicted diagrams agree surprisingly well with experimental data and they may be useful for the many cases where data are lacking or fragmentary. The phase diagrams and the thermodynamic data are shown to be a powerful tool for the understanding of interface reactions of metallic contacts to GaAs and hence for the development of improved contact materials.     

Thermodynamic modeling of the Au-In-Sb ternary system

The phase diagram of the Au-In-Sb ternary system is of importance in predicting the interface reaction between In-based solders and the Au substrate. Using the calculated phase diagram method and based on experimental data of thermodynamic properties and phase boundaries, the Au-Sb binary system was assessed, and the In-Sb binary system was revised. On the basis of the constituent binary systems, Au-Sb, In-Sb, and Au-In, the Au-In-Sb ternary system was modeled. Several isothermal and vertical sections were calculated, among which the one at 500 K reproduces the experimental diagram well.     

On the Sn-Bi-Ag ternary phase diagram

The selection and evaluation of Pb-free solders requires information that is best determined through a knowledge of ternary and higher order phase diagrams. As part of an ongoing program on Pb-free solder phase diagrams at the National Institute of Standards and Technology, a thermodynamic model is formulated for the Sn-Bi-Ag phase diagram. Thermodynamic functions for the various phases obtained by fitting measured data for the three constituent binary systems are extrapolated to the ternary system using the method of Muggianu. Modeling results are compared to preliminary experimental data for the ternary system and are applied in the calculation of the solidification path.     

Thermodynamic database for phase diagrams in micro-soldering alloys

A thermodynamic database for the calculation of phase diagrams in micro-soldering alloy systems, which include the elements Pb, Bi, Sn, Sb, Cu, Ag, and Zn has been developed using the CALPHAD method. The various thermodynamic parameters for describing the Gibbs energies of the different constituent phases have been evaluated by optimizing experimental data on phase boundary compositions and thermochemical properties such as activity, heat of mixing and enthalpy of formation. The resulting database provides the means whereby the liquidus and solidus surfaces, isothermal and vertical section diagrams, phase percentages and the mole fraction of the phase constitutions etc., in multi-component soldering alloys can be readily calculated. Related information such as the surface tension and viscosity of the liquid phase can also be predicted, thus rendering the database as a valuable tool for developing leadbearing and lead-free solders.     

相图--解释金属化层稳定性和薄膜反应的热力学方法

介绍了计算相图的起因与发展 ,综述了利用 Gibbs生成自由能数据绘制简化的三元、四元相图的热力学方法 ,尤其是确定相图中直达连线的思想方法 ,最后给出了利用相图来解释金属化层稳定性和薄膜反应的应用实例。     

Thermodynamic Calculation of Phase Equilibria in the Sn-Ag-Cu-Ni-Au System

Sn-Ag-Cu base solders are the most promising candidates to substitute for Sn-Pb eutectic solder. Gold (Au) coatings are used to protect conductor surfaces from oxidation and thereby to promote solderability, and Ni is often used as a diffusion barrier layer between lead-free solders and substrates to restrict the growth of intermetallic compound layers. In the present work, thermodynamic calculations of phase equilibria in the Sn-Ag-Cu-Ni-Au system, which is of importance for developing lead-free solders, are carried out using the calculation of phase diagrams (CALPHAD) method. Substitutional solution and sublattice models are used to describe the solution and intermediate phases, respectively. Some examples of thermodynamic calculation are presented, and it is shown that the phase diagrams, liquidus projection, and thermodynamic properties can be predicted based on the present calculations.     

Condensed phase equilibria in the metal-In-P systems

Ternary phase diagrams have proven valuable for understanding the reactions between a metal contact and a compound semiconductor, as well as for choosing thermally stable electrical contacts in thermodynamic equilibrium with the semiconductor. Since InP is important for both optoelectronic and electronic devices, the metal-In-P systems are of particular interest. In this work, new portions of isothermal sections of the (Rh, Ir, Ru, Os)-In-P diagrams are presented. Then, since no compilation of the published metal-In-P phase diagrams is available, the diagrams are reviewed here. The features of these diagrams are discussed in terms of the thermodynamics of the metal-In-P systems, particularly the considerable thermodynamic stability of many of the transition metal phosphides. Finally, some of the phases in thermodynamic equilibrium with InP, particularly PdIn and Ni₂P, are highlighted for their potential for high-temperature contacts to InP.     

Thermodynamic database on microsolders and copper-based alloy systems

Recent progress on the thermodynamic databases of calculated phase diagrams in microsolders and Cu-based alloys is presented. A thermodynamic tool, Alloy Database for Microsolders (ADAMIS), is based on comprehensive experimental and thermodynamic data accumulated with the calculation of phase diagrams (CALPHAD) method and contains eight elements, namely, Ag, Bi, Cu, In, Sb, Sn, Zn, and Pb. It can handle all combinations of these elements and all composition ranges. The elements of Al and Au have also been added to ADAMIS within a limited range of compositions. Furthermore, a database of Cu-based alloys, including binary (Cu-X), ternary (Cu-Fe-X, Cu-Ni-X, and Cu-Cr-X), and multicomponent (Cu-Ni-Cr-Sn-Zn-Fe-Si) systems, has also been developed. Typical examples of the calculation and application of these data-bases are presented. These databases are expected to be a powerful tool for the development of Pb-free solders and Cu substrate materials as well as for promoting the understanding of the interfacial phenomena between them in electronic packaging technology.