Ternary Solder Research Articles

Effect of ANSA as an additive on electrodeposited Sn-Ag-Cu alloy coatings in deep eutectic solvent

This study investigates the electrodeposition of Sn-Ag-Cu ternary solder coating in a choline chloride-ethylene glycol DES using 1-amino-2-naphthol-4-sulfonic acid (ANSA) as an additive. The mechanism of ANSA was evaluated through UV–visible absorption spectroscopy, infrared spectroscopy, and CV. The results demonstrate that ANSA, as a multifunctional organic compound, influences the electrodeposition process through its sulfonic acid, amino, and naphthyl groups. When the ANSA concentration is below 600 ppm, its primary action is through an interfacial adsorption mechanism, where lone pairs of electrons on nitrogen and oxygen atoms adsorb onto the electrode surface, and the bulky naphthyl ring inhibits the formation of large deposits. As the ANSA concentration exceeds 600 ppm, complexation becomes the dominant mechanism, competing with the complexation of chloride ions (Cl−) in the choline chloride electrolyte. SEM analysis indicates that as the ANSA concentration increases, the deposited coatings become smoother, denser, and exhibit finer grain sizes. The Scharifker-Hills model was employed to analyze the CA curves before and after the addition of ANSA, revealing that the nucleation mechanism of Sn-Ag-Cu alloy deposition gradually transitions from instantaneous nucleation to progressive nucleation with increasing ANSA concentration.

Investigation of Sn–Bi–In ternary solders with compositions varying from In–Sn eutectic to 59 °C ternary eutectic point

Investigation of Sn–Bi–In ternary solders with compositions varying from In–Sn eutectic to 59 °C ternary eutectic point

Computational Study of the Thermodynamic Properties of Some Lead-free Solder Alloys

Activities of the components of the binary lead-free solder alloys Cu-Sn, and Ag-Cu were computed using the molecular interaction volume model (MIVM). The theoretical data have been compared with the corresponding experimental values. For the validity of the model parameters, the excess Gibbs free energy of mixing of Cu-Sn, and Ag-Cu liquid alloys have been determined and compared with the corresponding experimental data available in the literature. Similarly, the activities of Sn in ternary liquid alloys Sn-Ag-Cu were computed and examined with the available experimental data at 1000 K. It has been observed that the calculated activities of the components of the binary and ternary solder alloys have nearly the same tendency as the experimental data.

Pattern Formation by Spinodal Decomposition in Ternary Lead-Free Sn-Ag-Cu Solder Alloy

In comparison to Pb-based solders which have a toxic effect, the tin-silver-copper (SAC) family of alloys have relatively strong reliability and are widely used in the electronics industry. Phase separation and coarsening phenomenon on the surface of 96.5 wt. % Sn-3.0 wt. % Ag-0.5 wt. % Cu (SAC305) solder products exhibit special microstructural features and offer opportunities for the microstructure control of microelectronic interconnects. However, the formation mechanism of such morphological patterns is still unknown. Here, we applied a combination of experimental and phase field methods to study how such patterns form. It was observed that the pattern was Sn-rich and exhibited the characteristic morphology of spinodal decomposition. Contrary to earlier findings that only binary systems like Sn-Pb and Sn-Bi experienced such phenomena, spinodal decomposition was firstly observed in ternary solder system Sn-Ag-Cu. Morphology of Sn-rich patterns depended on whether the spinodal decomposition reacted completely. SAC305 solder alloy was easily decomposed by Sn component after being heated to roughly 260 °C. The above conclusions could offer theoretical support for quantitatively controlling the microstructure of solder alloys and would enhance the quality of related products.

Investigation of Sn–Bi–In ternary solders with compositions varying from Sn–Bi eutectic point to 76 °C ternary eutectic

Investigation of Sn–Bi–In ternary solders with compositions varying from Sn–Bi eutectic point to 76 °C ternary eutectic

Microstructure and Phase Investigation of Sn-58Bi-xCu Lead-Free Solder After Immersion in Sodium Chloride Solution

The changes in microstructure and phase of tin-bismuth-copper (Sn-58Bi-xCu) were investigated after immersion in 3.5 wt. % sodium chloride (NaCl) at variations of Cu micro-alloying at 0.25, 0.50, 0.75, 1.00 and 1.25 wt. %. The morphological observation revealed that the long crystal grains of the Cu-rich phase were produced as the amount of Cu increased. The phase analysis shows that at 0.5 wt. % Cu additions, the intermetallic compound od Cu6Sn5 began to form and dominate the microstructure. After immersion in NaCl, a porous structure was seen covering the surface of the ternary solder, indicating the formation of a defective corrosion protection layer. The predominance of Cu6Sn5 is believed to boost the galvanic corrosion coupling potential of the ternary solder. As a result, the more electrochemically reactive phase was pushed to be eliminated during immersion in 3.5 wt.% NaCl solution. Thus the black spots were formed. The presence of Cu6Sn5 was seen to be detrimental to the electrochemical performance of Sn-58Bi-xCu.

A short review: Properties of superconducting solder

Development of electronic devices were moving towards miniaturization, multifunction and increasingly specific service environment of solder interconnects, where this drive to the higher requirements on the solder properties. Without solder, it would be impossible to produce the infinite electronic devices that define the 21st century. Hence, solder is important in the design and engineering process. This review paper was summarized on the literature of the low-temperature solder systems for superconducting solder materials, which provide further theoretical basis for the study of superconducting solder of electronic and aerospace applications. Pb-Bi system is the most satisfactory solder as a superconducting solder, but due to the restrictions of the lead usage, so new Pb-free superconducting solder need to be invented. Of those Pb-free superconducting materials had been studied, the Sn-In-Bi ternary solder system show the greatest superconducting properties as compared to other Pb-free superconducting solder where TC = 6.9 K, HC2 (4.2 K) = 0.18 T and JC (4.2 K, 0.01 T) = 1.3 × 108 A/m2 respectively.

The Study of Interfacial Reaction between SnAgCu (SAC) Lead-free Solder Alloys and Copper Substrate: A Short Review

This paper is aimed to review and study the interfacial reaction between SnAgCu (SAC) lead-free solder alloys and common copper substrates. Among the lead-free solders, a ternary solder alloys, SnAgCu (SAC) based solder, is leading the lead-free solders as it has excellent thermal and electrical properties. The interfacial between solder alloy and substrate comprise an important characteristic in the reliability performance of a solder alloy. As the current industry has driven to miniaturization, high integration and multifunctionality, the reliability and durability of solder joints are gained attention for its long-term performance of electronic products. Therefore, in this short review, the interfacial reaction between SAC solder alloys and copper substrate will be focused. Besides, the effects of the addition of microalloying elements into SAC solder alloys will be discussed.

An Experimental Investigation on the Properties of Two Novel Ternary Solder Alloys Sn–0.5Cu–3Bi and Sn–1Cu–1Ni Replacing Lead

Lead is banned in the solder alloy composition, citing its inherent toxicity. The researchers were working towards the development of new lead free solder alloys which can replace the old Sn–Pb alloy. In the present paper two new solder alloys are introduced, Sn–0.5Cu–3Bi (96.5% Sn, 0.5% Cu, 3% Bi, all are % by wt) i.e. SCB305 and Sn–1Cu–1Ni (98% Sn–1% Cu–1% Ni) i.e. SCN110. The melting temperature of SCB305 and SCN110 are found to be 231.5 and 232.8°C, respectively. Therefore these two alloys can be used as solder material in electronic packages exposed to moderately higher temperature. Hardness of SCB305 and SCN110 are obtained as 19.8 and 16.1 HV. SCB305 and SCN110 have very good wetting characteristics with contact angle of 28.74° and good wetting characteristics with contact angle of 36.75°, respectively. Microstructure of SCB305 and SCN110 shows that Bi and Ni are evenly distributed in the Sn-matrix. The cost analysis revealed that SCB305 and SCN110 have cost of 23.05 and 20.65 $/kg. The properties of the new alloys were compared with that of SAC305 and SAC405. SCB305 and SCN110 are found to be perfect replacement of Sn–Pb alloy.

Fluidic Self-Assembly on Electroplated Multilayer Solder Bumps with Tailored Transformation Imprinted Melting Points

This communication presents fluidic self-assembly of Si-chip on a sequentially electroplated multilayer solder bump with tailored transformation imprinted melting points. The multilayer solder bump is a lead free ternary solder system, which provides a route to transform the melting point of interconnects for applications in solder directed fluidic self-assembly. The outermost metal layers form a low melting point Bi33.7In66.3 solder shell (72 °C). This solder shell enables fluidic self-assembly and self-alignment of freely in water suspended Si-dies at relatively low temperature (75 °C) leading to well-ordered chip arrays. The reduction of the free surface energy of the shell-water interface provides the driving force for the self-assembly. The lowermost metal layer is a high melting point solder and acts as a core. After the self-assembly is complete, a short reflow causes the transformation of the core and the shell yielding a stable high melting point solder with adjustable melting points. The chosen ternary solder system enables the realization of interconnects with melting points in the range of 112 °C to 206 °C.

Investigations on the properties of new lead free solder alloy composition – Sn-0.5Cu-3.5Bi

Abstract Lead is restricted in solder joints because of environmental legislations. In this study, a new ternary solder alloy Sn-0.5Cu-3.5Bi is proposed. Alloys prepared using induction furnace have been analysed for their material properties. Melting temperature lies in the range of 219.5−220.5 °C. Hardness value lies in the range of 20.5–20.8 Hv. Good wetting property have also been obtained. Grain boundaries were attained from the microstructure evaluation. A comparison with SAC305 and SAC405 also shows that the new alloy is having better properties. Sn-0.5Cu-3.5Bi is a new lead free solder alloy for electronic packages subjected to moderately high temperature surroundings.

Estimation of the viscosities of melt for Sn-based ternary lead-free solder alloys

ABSTRACTThe proposed thermodynamic parameters were extended to the liquid ternary alloy system, and a prediction model of the viscosity for liquid alloy was proposed. The viscosity of the ternary liquid lead-free solder alloy was calculated using the thermodynamic parameters and the prediction model for viscosity of ternary liquid alloy. The results show that the calculated viscosity of the ternary liquid lead-free solder alloy is consistent with the reported experimental values, and the prediction model has good rationality. At the same time, compared with the complex Seetharaman model, Moelwyn-Hughes model and Kaptay model, the prediction model for viscosity of ternary liquid alloy depends only on the element's basic physical parameter (density, melting temperature, absolute atomic mass, electro-negativity, electron density, molar volume, and Pauling radius). The entire calculation process is relatively simple. Additionally, the proposed prediction model of viscosity can be applied to system calculations having similar physical and thermodynamic properties as ternary liquid Tin-based lead-free alloys.

A phenomenological study of a Sn–Ag–Al composite solder reinforced with Mg–MWCNT: Improved electrical conductivity and thermo-physical performance

A Sn–Ag–Al composite solder alloy reinforced with Mg–multi-walled carbon nanotubes (MWCNT) was prepared using a powder metallurgy (P/M) method. The electrical resistivity of the Sn–Ag–Al–Mg–MWCNT composite solder alloy decreased to 21.91×10−6Ω·cm when the Sn–Ag–Al conventional solder alloy (36.15×10−6Ω·cm) was reinforced with 2.87wt% Mg and 0.60wt% MWCNT (3.47wt% Mg–MWCNT). The reinforcement by the Mg–MWCNT also provided relatively lower density (6.53g/cm3) to the composite solder alloy compared to the conventional solder alloy (7.34g/cm3). The onset melting temperature of the quinary solder alloy was 204.2°C, which was 10.0°C lower than that of the ternary solder alloy at 214.2°C. The wettability of the composite solder powders after reflow on the quartz substrate was increased due to the improved solder fluidity aided by the MWCNT bundle. The improved electrical and thermo-physical performance was induced by a combination of interactions driven by ionic and covalent bonds between the Mg atoms and the MWCNT, and by intermetallic compound formation between the Mg atoms and the other solder constituents.

Composition dependences of thermodynamical properties associated with Pb-free ternary, quaternary, and quinary solder systems

In the present study, Chou’s General Solution Model (GSM) has been used to predict the enthalpy and partial enthalpies of mixing of the liquid Ag–In–Sn ternary, Ag–In–Sn–Zn quaternary, and Ag–Au–In–Sn–Zn quinary systems. These are of technical importance to optimize lead-free solder alloys, in selected cross-sections: xIn/xSn = 0.5/0.5 (ternary), Au–In0.1–Sn0.8–Zn0.1, Ag–In0.1–Sn0.8–Zn0.1 (quaternary), and t = xAu/xIn = 1, xIn = xSn = xZn (quinary) at 1173, 773, and 773 K, respectively. Moreover, the activity of In content in the ternary alloy system Ag–In–Sn has been calculated and its result is compared with that determined from the experiment, while the activities of Ag contents associated with the alloys mentioned above have been calculated. The other traditional models such as of Colinet, Kohler, Muggianu, Toop, and Hillert are also included in calculations. Comparing those calculated from the proposed GSM with those determined from experimental measurements, it is seen that this model becomes considerably realistic in computerization for estimating thermodynamic properties in multicomponent systems.

Composition dependences of thermodynamical properties associated with Pb-free ternary, quaternary, and quinary solder systems

Composition dependences of thermodynamical properties associated with Pb-free ternary, quaternary, and quinary solder systems

The measurements of electrical and thermal conductivity variations with temperature and phonon component of the thermal conductivity in Sn–Cd–Sb, Sn–In–Cu, Sn–Ag–Bi and Sn–Bi–Zn alloys

The electrical and thermal conductivity variations with temperature for lead-free ternary solders, namely Sn-41.39 at.% Cd-6.69 at.% Sb, Sn-49 at.% In-1 at.% Cu, Sn-50 at.% Ag-10 at.% Bi and Sn-32 at.% Bi-3 at.% Zn alloys, were measured by the d.c. four-point probe method and radial heat flow apparatus, respectively. The contributions of electrons and phonons to the thermal conductivity were separately determined by using the measured values of the thermal and electrical conductivities obtained by the Wiedemann–Franz law in the lead-free ternary solders. The percentages of the phonon component of thermal conductivity were found to be in the range of 46–55%, 46–50%, 38–47% and 69–73% for Sn-41.39 at.% Cd-6.69 at.% Sb, Sn-49 at.% In-1 at.% Cu, Sn-50 at.% Ag-10 at.% Bi and Sn-32 at.% Bi-3 at.% Zn alloys at the ranges of 318–443 K temperature, respectively. The temperature coefficients (α) of electrical conductivity for the lead-free ternary solders were found to be 2.47 × 10−3, 4.97 × 10−3, 1.14 × 10−3 and 1.00 × 10−3 K−1, respectively. The thermal conductivities of the solid phases at their melting temperature and the thermal temperature coefficients for the lead-free ternary solders were also found to be 47.72 ± 2.38, 68.57 ± 3.42, 73.52 ± 3.67, 37.53 ± 1.87 W/Km and 1.47 × 10−3, 1.48 × 10−3, 1.85 × 10−3 and 2.21 × 10−3 K−1, respectively.

Interfacial Reactions of Low-Melting Sn-Bi-Ga Solder Alloy on Cu Substrate

A new ternary solder alloy Sn62Bi32Ga6 (in wt.%) with melting point of 128°C, which is 10°C lower than that of eutectic Sn-Bi, has been developed. The composition was obtained by adding the maximum possible amount of Ga without causing Ga segregation and the formation of a liquid phase inside the solder. Solders were reflowed on Cu substrates to investigate their interfacial morphologies during liquid reactions. The only intermetallic compound detected at the interfaces was CuGa2, which initially formed with a discrete basin type at the interfaces. As the reflow time was increased, the basin-type compound formed a continuous layer that inhibited Cu dissolution. Solid-state aging tests were also performed on the system, and the activation energy for the formation of CuGa2 was found to be 2.82 kJ/mol, which is much lower than that of the Cu-Sn compound.

Application of a Ternary Zn-Based Solder Alloy for Joining of AZ31B Magnesium Alloy with Ultrasonic Support

Contribution deals with soldering of Mg alloy AZ31B by ternary solder ZnAl6Ag6 with ultrasonic support. Suggested solder has been analyzed from many aspects. Microstructure of solder consistutes of solid solution α-Al (FCC_Al), β-Zn (HCP_Zn) and intermetallic phases AgZn3 and AlAg3. Melting temperature of solder 386.8 °C has been determined by DSC analysis. Metallurgical process of ultrasonic soldering has run at 410 °C for 3 s. Soldered joint has been constituted by eutectic ternary structure β-Mg17(ZnAl)12, solid solution α - Mg, which contains Al and Ag elements. At solder-substrate interface, there has been formed intermetallic phase Mg2Zn11. The highest value of microhardness has been 260 HV. To predict lifetime of soldered joint, calculations in software Thermo-Calc has been performed.

Reduced Electrical Resistivity of Ternary Solder Alloy of Tin–Copper–Sulfur: An Anti-Oxidative Role of Sulfur in Binary Solder Alloy of Tin–Copper

Reduced Electrical Resistivity of Ternary Solder Alloy of Tin–Copper–Sulfur: An Anti-Oxidative Role of Sulfur in Binary Solder Alloy of Tin–Copper

Design of lead-free candidate alloys for low-temperature soldering applications based on the hypoeutectic Sn–6.5Zn alloy

The coupling effect of both minor alloying addition and reducing the amount of Zn phase have been proposed as an important strategy to improve the integrity and reliability of eutectic Sn–9Zn solder joints. In this work, the changes in microstructures, thermal behaviors and mechanical properties associated with the alloying of Ni and Sb to eutectic Sn–Zn after reducing the amount of Zn phase were explored. Thermal analysis confirmed that Ni and Sb additions being effective in reducing the amount of undercooling, while the melting temperature and pasty range remained at the hypoeutectic Sn–6.5Zn level. The resulting ultimate (UTS), yield tensile strength (YS) and elongation (El) of Sn–6.5Zn–0.5Ni and Sn–6.5Zn–0.5Sb alloys were experimentally determined and compared with the corresponding results of plain Sn–6.5Zn solder alloy. It was found that the Sn–6.5Zn–0.5Ni and Sn–6.5Zn–0.5Sb alloys examined comply with the compromise between high mechanical strength and ductility. Microstructural analysis revealed that the origin of change in mechanical properties was attributed to the enhanced solid solution effect of Sb and the flower shaped (Ni, Zn)3Sn4 intermetallics (IMC) phase produced by Ni addition. The Sn–6.5Zn–0.5Sb alloy has the highest UTS and appropriate ductility of all alloys examined. This finding indicates the capability of newly developed ternary solder alloys to serve a much wider array of value-added applications.