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This study aims to address the problem of low-temperature wave soldering in industry production with Sn-9Zn-2.5 Bi-1.5In alloys and develop qualified process parameters. Sn–Zn eutectic alloys are lead-free solders applied in consumer electronics due to their low melting point, high strength, and low cost. In the electronic assembly industry, Sn–Zn eutectic alloys have great potential for use.

This paper explored developing and implementing process parameters for low-temperature wave soldering of Sn–Zn alloys (SN-9ZN-2.5BI-1.5 In). A two-factor, three-level design of the experiments experiment was designed to simulate various conditions parameters encountered in Sn–Zn soldering, developed the nitrogen protection device of waving soldering and proposed the optimal process parameters to realize mass production of low-temperature wave soldering on Sn–Zn alloys.

The Sn-9Zn-2.5 Bi-1.5In alloy can overcome the Zn oxidation problem, achieve low-temperature wave soldering and meet IPC standards, but requires the development of nitrogen protection devices and the optimization of a series of process parameters. The design experiment reveals that preheating temperature, soldering temperature and flux affect failure phenomena. Finally, combined with the process test results, an effective method to support mass production.

In term of overcome Zn’s oxidation characteristics, anti-oxidation wave welding device needs to be studied. Various process parameters need to be developed to achieve a welding process with lower temperature than that of lead solder(Sn–Pb) and lead-free SAC(Sn-0.3Ag-0.7Cu). The process window of Sn–Zn series alloy (Sn-9Zn-2.5 Bi-1.5In alloy) is narrow. A more stringent quality control chart is required to make mass production.

In this research, the soldering temperature of Sn-9Zn-2.5 Bi-1.5In is 5 °C and 25 °C lower than Sn–Pb and Sn-0.3Ag-0.7Cu(SAC0307). To the best of the authors’ knowledge, this work was the first time to apply Sn–Zn solder alloy under actual production conditions on wave soldering, which was of great significance for the study of wave soldering of the same kind of solder alloy.

Low-temperature wave soldering can supported green manufacturing widely, offering a new path to achieve carbon emissions for many factories and also combat to international climate change.

There are many research papers on Sn–Zn alloys, but methods of achieving low-temperature wave soldering to meet IPC standards are infrequent. Especially the process control method that can be mass-produced is more challenging. In addition, the metal storage is very high and the cost is relatively low, which is of great help to provide enterprise competitiveness and can also support the development of green manufacturing, which has a good role in promoting the broader development of the Sn–Zn series.

This study aims to investigate the impact of indium (In) content on the thermal properties, microstructure and mechanical properties of Sn-3Ag-3Sb-xIn (x = 0, 1, 2, 3, 4, 5 Wt.%) solders to enhance the performance of tin-based solder under demanding conditions and to meet the urgent need for high-reliability microelectronic interconnection materials in emerging sectors such as automotive intelligent technology, 5G communication technology and high-performance computing.

In this study, Sn-3Ag-3Sb-xIn solder alloys were prepared. The thermal properties of the solder alloys were characterised by differential scanning calorimetry. Subsequently, optical microscopy, scanning electron microscopy, X-ray diffraction and an electron probe X-ray microanalyser were used to analyse the influence of the In content on the microstructure of the solder. The mechanical properties of solder alloys were determined through tensile testing.

As the In content increased, the melting temperature of the Sn-3Ag-3Sb-xIn solder decreased, accompanied by less nucleation undercooling and an expanded melting range. The incorporation of In led to an enhancement in the yield and tensile strengths of the Sn-3Ag-3Sb-xIn solder alloys, but with a concomitant decrease in plasticity. In comparison to commercial Sn-3.0Ag-0.5Cu solder alloys, the yield strength and tensile strength of the Sn-3Ag-3Sb-3In alloy increased by 8.64 and 21.69 MPa, respectively, while the elongation decreased by 11.48%.

Sn-3Ag-3Sb-3In solder alloy was the most appropriate and expected comprehensive properties. The enhancements will provide substantial assistance and precise data references for the interconnection requirements in high-strength interconnection fields, such as automotive intelligent technology, 5G communication technology and high-performance computing.

This study aims to focus on the surface mount technology (SMT) mass production process of Sn-9Zn-2.5Bi-1.5In solder. It explores it with some components that will provide theoretical support for the industrial SMT application of Sn-Zn solder.

This study evaluates the properties of solder pastes and selects a more appropriate reflow parameter by comparing the microstructure of solder joints with different reflow soldering profile parameters. The aim is to provide an economical and reliable process for SMT production in the industry.

Solder paste wettability and solder ball testing in a nitrogen environment with an oxygen content of 3,000 ppm meet the requirements of industrial production. The printing performance of the solder paste is good and can achieve a printing rate of 100–160 mm/s. When soldering with a traditional stepped reflow soldering profile, air bubbles are generated on the surface of the solder joint, and there are many voids and defects in the solder joint. A linear reflow soldering profile reduces the residence time below the melting point of the solder paste (approximately 110 s). This reduces the time the zinc is oxidized, reducing solder joint defects. The joint strength of tin-zinc joints soldered with the optimized reflow parameters is close to that of Sn-58Bi and SAC305, with high joint strength.

This study attempts to industrialize the application of Sn-Zn solder and solves the problem that Sn-Zn solder paste is prone to be oxidized in the application and obtains the SMT process parameters suitable for Sn-9Zn-2.5Bi-1.5In solder.

This study aims to investigate the influence of different solder alloy materials on passive devices during laser soldering process. Solder alloy material has been found to significantly influence the solder joint’s quality, such as void formation that can lead to cracks, filling time that affects productivity and fillet shape that determines the solder joint’s reliability.

Finite volume method (FVM)-based simulation that was validated using real laser soldering experiment is used to evaluate the effect of various solder alloy materials, including SAC305, SAC387, SAC396 and SAC405 in laser soldering. These solders are commonly used to assemble the pin-through hole (PTH) capacitor onto the printed circuit board.

The simulation results show how the void ratio, filling time and flow characteristics of different solder alloy materials affect the quality of the solder joint. The optimal solder alloy is SAC396 due to its low void ratio of 1.95%, fastest filling time (1.3 s) to fill a 98% PTH barrel and excellent flow characteristics. The results give the ideal setting for the parameters that can increase the effectiveness of the laser soldering process, which include reducing filling time from 2.2 s to less than 1.5 s while maintaining a high-quality solder joint with a void ratio of less than 2%. Industries that emphasize reliable soldering and effective joint formation gain the advantage of minimal occurrence of void formation, quick filling time and exceptional flowability offered by this solution.

This research is expected not only to improve solder joint reliability but also to drive advancements in laser soldering technology, supporting the development of efficient and reliable microelectronics assembly processes for future electronic devices. The optimized laser soldering material will enable the production of superior passive devices, meeting the growing demands of the electronics market for smaller, high-performance electronic products.

The comparison of different solder alloy materials for PTH capacitor assembly during the laser soldering process has not been reported to date. Additionally, volume of fluid numerical analysis of the quality and reliability of different solder alloy joints has never been conducted on real PTH capacitor assemblies.

The purpose of this study is the formation and growth of nanoscale intermetallic compounds (IMCs) when laser is used as a heat source to form solder joints.

This study investigates the Sn/Cu and Sn-0.1AlN/Cu structure using laser soldering under different laser power: (200, 225 and 250 W) and heating time: (2, 3 and 4 s).

The results show clearly that the formation of nano-Cu₆Sn₅ films is feasible in the laser heating (200 W and 2 s) with Sn/Cu and Sn-0.1AlN/Cu system. The nano-Cu₆Sn₅ films with thickness of 500 nm and grains with 700 nm are generally parallel to the Cu surface with Sn-0.1AlN. Both IMC films thickness of Sn/Cu and Sn-0.1AlN/Cu solder joints gradually increased from 524.2 to 2025.8 nm as the laser heating time and the laser power extended. Nevertheless, doping AlN nanoparticles can slow down the growth rate of Cu₆Sn₅ films in Sn solder joints due to its adsorption.

The formation of nano-Cu₆Sn₅ films using laser heating can provide a new method for nanofilm development to realize the metallurgical interconnection in electronic packaging.

The purpose of this study is to investigate the effects of Ce and Sb doping on the microstructure and thermal mechanical properties of Sn-1.0Ag-0.5Cu lead-free solder. The effects of 0.5%Sb and 0.07%Ce doping on microstructure, thermal properties and mechanical properties of Sn-1.0Ag-0.5Cu lead-free solder were investigated.

According to the mass ratio, the solder alloys were prepared from tin ingot, antimony ingot, silver ingot and copper ingot with purity of 99.99% at 400°C. X-ray diffractometer was adopted for phase analysis of the alloys. Optical microscopy, scanning electron microscopy and energy dispersive spectrometer were used to study the effect of the Sb and Ce doping on the microstructure of the solder. Then, the thermal characteristics of alloys were characterized by a differential scanning calorimeter (DSC). Finally, the ultimate tensile strength (UTS), elongation (EL.%) and yield strength (YS) of solder alloys were measured by tensile testing machine.

With the addition of Sb and Ce, the ß-Sn and intermetallic compounds of solders were refined and distributed more evenly. With the addition of Sb, the UTS, EL.% and YS of Sn-1.0Ag-0.5Cu increased by 15.3%, 46.8% and 16.5%, respectively. The EL.% of Sn-1.0Ag-0.5Cu increased by 56.5% due to Ce doping. When both Sb and Ce elements are added, the EL.% of Sn-1.0Ag-0.5Cu increased by 93.3%.

The addition of 0.5% Sb and 0.07% Ce can obtain better comprehensive performance, which provides a helpful reference for the development of Sn-Ag-Cu lead-free solder.

The purpose of the present work is to study the impacts of rapid cooling and Tb rare-earth additions on the structural, thermal and mechanical behavior of Bi–0.5Ag lead-free solder for high-temperature applications.

Effect of rapid solidification processing on structural, thermal and mechanical properties of Bi-Ag lead-free solder reinforced Tb rare-earth element.

The obtained results indicated that the microstructure consists of rhombohedral Bi-rich phase and Ag99.5Bi0.5 intermetallic compound (IMC). The addition of Tb could effectively reduce the onset and melting point. The elastic modulus of Tb-containing solders was enhanced to about 90% at 0.5 Tb. The higher elastic modulus may be attributed to solid solution strengthening effect, solubility extension, microstructure refinement and precipitation hardening of uniform distribution Ag99.5Bi0.5 IMC particles which can reasonably modify the microstructure, as well as inhibit the segregation and hinder the motion of dislocations.

It is recommended that the lead-free Bi-0.5Ag-0.5Tb solder be a candidate instead of common solder alloy (Sn-37Pb) for high temperature and high performance applications.

This study aims to investigate the design configuration for an optimum solder height of reinforced SAC305 solder joint in an ultra-fine capacitor assembly.

A multiphase finite volume model is developed for reflow soldering simulations to determine the fillet height of reinforced SAC305 solder joint in an ultra-fine capacitor assembly. Different solders, namely SAC305-x, SAC305-xNiO and SAC305-xTi, with varying percentage weight compositions of nanoparticles (x = 0 Wt.%, 0.01 Wt.%, 0.05 Wt.%, 0.10 Wt.%, 0.15 Wt.%) are investigated. A reflow soldering experiment is also conducted, and the cross-sections of the reflowed packages are examined using a High-Resolution Transmission Electron Microscope (HRTEM). The optimum design configurations (nanoparticle composition and material) for the solder fillet height are investigated using the Taguchi orthogonal array method.

Good correlations were recorded between the HRTEM micrographs and the numerical predictions of the nanoparticles' distribution in the molten solder. The numerical prediction of the fillet height also agrees with the experiment, with a maximum disparity of 5.43%. It was found that Ti nanoparticles, having the smallest density compared to NiO and, exhibit the highest buoyancy effect in the molten solder. The Taguchi analysis revealed that the nanoparticles' material factor is more significant than the Wt.% factor for an optimum fillet height. An optimum design configuration for fillet height was established as SAC 305–0.15 Wt.% Ti, corresponding to a 41.13% improvement of the plain SAC 305 solder.

The fillet height of solder joints greatly influences the solder joint reliability of miniaturized electronic packages. Solder joint reliability of ultra-fine capacitors can be improved using this study's findings on the optimum design configuration for the capacitor's solder fillet. The study’s findings can be practically implemented in industries such as electronics manufacturing, where enhanced solder joint reliability is critical.

Investigation of the optimum design configuration for reinforced SAC305 solder fillet is almost nonexistent in the literature. This study explored the optimization of fillet height of reinforced SAC305 solder joints in miniaturized capacitor assembly.

The reliability of solder joints is closely related to the growth of an intermetallic compound (IMC) layer between the lead-free solder and substrate interface. This paper aims to investigate the growth behavior of the interfacial IMC layer during isothermal aging at 125°C for Sn-3Ag-3Sb-xIn/Cu (x = 0, 1, 2, 3, 4, 5 Wt.%) solder joints with different In contents and commercial Sn-3Ag-0.5Cu/Cu solder joints.

In this paper, Sn-3Ag-3Sb-xIn/Cu (x = 0, 1, 2, 3, 4, 5 Wt.%) and commercial Sn-3Ag-0.5Cu/Cu solder were prepared for bonding Cu substrate. Then these samples were subjected to isothermal aging for 0, 2, 8, 14, 25 and 45 days. Scanning electron microscopy and transmission electron microscopy were used to analyze the soldering interface reaction and the difference in IMC growth behavior during the isothermal aging process.

When the concentration of In in the Sn-3Ag-3Sb-xIn/Cu solder joints exceeded 2 Wt.%, a substantial amount of InSb particles were produced. These particles acted as a diffusion barrier, impeding the growth of the IMC layer at the interface. The growth of the Cu₃Sn layer during the aging process was strongly correlated with the presence of In. The growth rate of the Cu₃Sn layer was significantly reduced when the In concentration exceeded 3 Wt.%.

The addition of In promotes the formation of InSb particles in Sn-3Ag-3Sb-xIn/Cu solder joints. These particles limit the growth of the total IMC layer, while a higher In content also slows the growth of the Cu₃Sn layer. This study is significant for designing alloy compositions for new high-reliability solders.

This study aims to investigate the effect of incorporating cobalt (Co) into Sn-58Bi alloy on its phase composition, tensile properties, hardness and thermal aging performances. The fracture morphologies of tensile-tested solders are also investigated to correlate the microstructural changes with tensile properties of the solder alloys. Then, the thermal aging performances of the solder alloys are investigated in terms of their intermetallic compound (IMC) layer morphology and thickness.

The Sn-58Bi and Sn-58Bi-xCo, where x = 1.0, 1.5 and 2.0 Wt.%, were prepared using the flux doping technique. X-ray diffraction (XRD) is used to study the phase composition of the solder alloys, whereas scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX) are used to investigate the microstructure, fractography and compositions of the solders. Tensile properties such as ultimate tensile strength (UTS), Young’s modulus and elongation are tested using the tensile test, whereas the microhardness value is gained from the micro-Vickers hardness test. The morphology and thickness of the IMC layer at the solder’s joints are investigated by varying the thermally aging duration up to 56 days at 80°C.

XRD analysis shows the presence of Co₃Sn₂ phase and confirms that Co was successfully incorporated via the flux doping technique. The microstructure of all Sn-58Bi-xCo solders did not differ significantly from Sn-58Bi solders. Sn-58Bi-2.0Co solder exhibited optimum properties among all compositions, with the highest UTS (87.89 ± 2.55 MPa) at 0.01 s⁻¹ strain rate and the lowest IMC layer thickness at the interface after being thermally aged for 56 days (3.84 ± 0.67 µm).

The originality and value of this research lie in its novel exploration of the flux doping technique to introduce minor alloying of Co into Sn-58Bi solder alloys, providing new insights into enhancing the properties and performance of these solders. This new Sn-Bi-Co alloy has the potential to replace lead-containing solder alloy in low-temperature soldering.