Microstructure Of Solder Research Articles

Quaternary low melting point Sn-Bi-in-xGa solder with improved mechanical performance for advanced electronic packaging

Managing thermal stress is important for ensuring the yield of chip integration and packaging. The development of appropriate low melting point solders has become the key to mitigating thermal stress during the assembling, which aligns well with the demands of next-generation interconnection technologies. In this study, we developed a quaternary low melting point solder based on Sn-Bi-In-xGa (x = 0, 0.1, 0.3, 0.5, 1.0, 1.5, wt%). The addition of Ga not only lowers the solder's melting point but also enhances its wettability. We also studied how the increase of Ga in the solder alloy influences the microstructure and shear test failure mechanism during aging. Upon subjecting solder joints to a 10-min reflow process at 100 °C with Cu substrates, two distinct types of intermetallic compound (IMC) were observed: Cu6(Sn, In)5 when Ga content was ≤0.1 wt% and γ3-Cu9Ga4 when Ga content was ≥0.3 wt%. The stable property of γ3-Cu9Ga4 IMC ensures the mechanical stability of the joints during aging. Therefore, the addition of an appropriate amount of Ga (0.3 wt%) can improve the mechanical performance of solder joints during aging. These findings offer valuable insights for the development of high-performance low-melting-point solders in microelectronics, shedding light on the mechanisms underlying the influence of Ga content on solder microstructures and mechanical reliability during thermal aging.

Properties of Sn-3.0Ag-0.5Cu solder joints under various soldering conditions: Reflow vs. Laser vs. Intense Pulsed Light soldering

In this study, the properties of solder joints were compared after bonding process using different energy sources. Various soldering methods were employed, including reflow, laser, and Intense Pulsed Light (IPL) soldering. When reflow soldering was performed for a relatively long time, coarse solder microstructures and interfacial intermetallic compound (IMC) grains were formed. Laser and IPL soldering, which have rapid heating/cooling times, formed fine solder microstructure and thin interfacial IMCs. Then, it was confirmed that Cu6Sn5 and Cu3Sn IMCs were formed at the SAC305/OSP (organic solderability preservative) interface and (Cu,Ni)6Sn5, Ni–Sn–P, and Ni3P were formed at the SAC305/ENEPIG (electroless nickel electroless palladium immersion gold) interface. An observation of the IMC grain morphology under various soldering conditions revealed that (Cu,Ni)6Sn5 was formed on the ENEPIG substrate, which was polygonal and smaller than on the OSP substrate. The shear strength of the joint increased in the order of reflow, laser, and IPL soldering. Additionally, ductile fractures occurred under all conditions. The IPL soldering joint had a thinner IMC compared to reflow soldering, and moderate interface roughness and bonding area compared to laser soldering. Based on the obtained results, a next-generation IPL soldering method is proposed to improve the properties of Sn-3.0Ag-0.5Cu solder joints.

Microstructure, joining mechanism, mechanical properties and optimization of inactive solder (Sn9Zn) in low temperature ultrasonic soldering of AlN ceramics and 2024Al

With the development of the electronic packaging industry, there is an increased demand for enhanced strength in DBA substrates. Ultrasonic soldering technology allows low-temperature joining of ceramic-metal materials under ambient air conditions. In this paper, we successfully achieved the joining between AlN ceramics and 2024Al using Sn9Zn solder and ultrasonic soldering technique, while also analyzing the joining mechanism through Comsol software simulations. It was observed that under the appropriate ultrasonic amplitude and frequency, the Sn9Zn solder exhibited complete wetting with both base materials, resulting in reliable joints. Building upon this finding, the conventional Sn9Zn solder was further optimized by adding Sb element. The addition of Sb element led to the formation of Zn4Sb3 phase and β-Sn(Sb) phase with Sb acting as solute. Among them, the generation of β-Sn(Sb) solid solution phase effectively improved the joint strength. The maximum joint strength was achieved at an average value of 75.066 MPa when the Sb content reached 1 wt. %. At this point, the failure occurred within the AlN ceramic base material.

Design of Ni-rGO reinforced Sn2.5Ag0.7Cu0.1Ce composite solder based on micro-alloying and composite principles: Microstructure and properties

Based on the principles of micro-alloying and composite, the graphene reinforced Sn2.5Ag0.7Cu0.1Ce composite solder was designed. Ni nanoparticle-modified reduced graphene oxide (Ni-rGO) was prepared by thermal decomposition method, and the powder-melting method was proposed for the first time to prepare Ni-rGO reinforced Sn2.5Ag0.7Cu0.1Ce composite solder. The microstructure, wettability, electrical resistivity, and mechanical properties of the composite solder were systematically studied. Results indicated that the Ni nanoparticles uniformly adhered to the rGO with a size of 26.3 nm. The effective incorporation of Ni-rGO into the solder matrix was achieved. The result broke the technical difficulty that graphene cannot be effectively added to low melting point metals. With the addition of Ni-rGO, the grain size gradually decreased, and the eutectic structures increased. Deep etching results revealed that columnar β-Sn was stacked from layered β-Sn, the addition of 0.05 wt% Ni-rGO led to an increase in sheet-like Ag3Sn within the eutectics. Additionally, Ni-rGO was found at the grain boundaries of composite solder, serving as nucleation sites for Ag3Sn and Cu6Sn5. At an addition of 0.05 wt%, the tensile strength reaches a maximum of 58.1 MPa, with elongation of 33.8%, surpassing the strength of commercial Sn3.0Ag0.5Cu solder. Therefore, the high-strength and tough composite solder was obtained. This study offered a new approach for the development of low-melting-point composite materials.

Microstructure and mechanical behavior of Sn15Bi-xAg\Cu solder joints during isothermal aging

Purpose This paper aims to focus on the reliability of Sn15Bi–xAg and Sn15Bi–xCu solder joints during isothermal aging. Design/methodology/approach The effects of Ag or Cu additions on the microstructure, interfacial metallic compound layer and shear strength of Sn–15Bi (Sn15Bi) based solder joints during were investigated. The effects of Ag or Cu additions on the microstructure and tensile properties of Sn15Bi-based bulk solders were also investigated to provide a comprehensive analysis. The interfacial morphology and microstructure were observed by scanning electron microscopy and the composition in the structure was examined by energy dispersive spectrometer. The shear tests were carried out on the as-soldered and as-aged joints using a ball shear tester. Findings The results revealed that by adding Ag or Cu, the microstructure of Sn15Bi solder can be refined. Ag addition increased the tensile strength of Sn15Bi solder but had little effect on elongation. However, Cu addition decreased the tensile strength and elongation of Sn15Bi solder. For solder joints, Ag addition increased the shear strength and toughness of Sn15Bi/Cu joints but Cu addition decreased the shear strength and toughness of Sn15Bi/Cu joints. Originality/value The authors can potentially provide a replacement for Sn40Pb traditional solder with Sn15Bi solder by alloying Ag or Cu due to its lower cost and similar melting point as Sn–Pb solder.

Microstructure, hardness, electrical, and thermal conductivity of SZCN solder reinforced with TiO2 and ZrO2 nanoparticles fabricated by powder metallurgy method

The microstructure and characterization of Sn–Zn–Cu–Ni (SZCN) solder alloy reinforced with TiO2 and ZrO2 nanoparticles (NPs) synthesized by powder metallurgy were investigated. Sn, Zn, Cu and Ni metallic powders were mixed mechanical by 10:1 ball to powder ratio with 300 rpm speed for 2 h. Then 0.5 wt% from nano ZrO2 or TiO2 was mixed by the same parameters with the mixed metal powder. The morphologies and microstructures development during the fabrication process was investigated by X-ray diffractometer (XRD), optical microscope (OM), and scanning electron microscope (SEM) with energy dispersive X-ray spectrometry (EDX). The results reveal an improved distribution of TiO2 or ZrO2 NPs in the SZCN matrix solder, which resulted in an improvement in its density. The analyses of microstructural demonstrated that the addition of TiO2 or ZrO2 NPs to SZCN solder results in the grain refinement of the β-Sn phase, besides the formation of Ni3Sn IMC with small size and uniform distribution. The microhardness was enhanced as a result of the addition of TiO2 or ZrO2 NPs. The experimental results showed that the SZCN-ZrO2 composite solder had the greatest hardness and stress exponent values due to its effectiveness in suppressing the growth of β-Sn grains and the pile-up of dislocations. Both the electrical and thermal conductivities were improved by incorporating TiO2 NPs compared to other solders.

Influences of low In alloying and aging on microstructure and plastic deformation behavior of Sn-58Bi solder

Influences of low In alloying and aging on microstructure and plastic deformation behavior of Sn-58Bi solder

The role of microstructure in the thermal fatigue of solder joints

Thermal fatigue is a common failure mode in electronic solder joints, yet the role of microstructure is incompletely understood. Here, we quantify the evolution of microstructure and damage in Sn-3Ag-0.5Cu joints throughout a ball grid array (BGA) package using EBSD mapping of localised subgrains, recrystallisation and heavily coarsened Ag3Sn. We then interpret the results with a multi-scale modelling approach that links from a continuum model at the package/board scale through to a crystal plasticity finite element model at the microstructure scale. We measure and explain the dependence of damage evolution on (i) the β-Sn crystal orientation(s) in single and multigrain joints, and (ii) the coefficient of thermal expansion (CTE) mismatch between tin grains in cyclic twinned multigrain joints. We further explore the relative importance of the solder microstructure versus the joint location in the array. The results provide a basis for designing optimum solder joint microstructures for thermal fatigue resistance.

Microstructural Optimization of Sn-58Bi Low-Temperature Solder Fabricated by Intense Pulsed Light (IPL) Irradiation

In this study, intense pulsed light (IPL) soldering was employed on Sn-58Bi solder pastes with two distinct particle sizes (T3: 25–45 μm and T9: 1–8 μm) to investigate the correlation between the solder microstructure and mechanical properties as a function of IPL irradiation times. During IPL soldering, a gradual transition from an immature to a refined to a coarsened microstructure was observed in the solder, impacting its mechanical strength (hardness), which initially exhibited a slight increase followed by a subsequent decrease. It is noted that hardness measurements taken during the immature stage may exhibit slight deviations from the Hall–Petch relationship. Experimental findings revealed that as the number of IPL irradiation sessions increased, solder particles progressively coalesced, forming a unified mass after 30 sessions. Subsequently, after 30–40 IPL sessions, notable voids were observed within the T3 solder, while fewer voids were detected at the T9-ENIG interface. Following IPL soldering, a thin layered structure of Ni3Sn4 intermetallic compound (IMC) was observed at the Sn-58Bi/ENIG interface. In contrast, reflow soldering resulted in the abundant formation of rod-shaped Ni3Sn4 IMCs not only at the reaction interface but also within the solder bulk, accompanied by the notable presence of a P-rich layer beneath the IMC.

Effect of Sb Content on the Microstructure and Mechanical Properties of Eutectic SnPb Solder.

SnPb solder was widely used in electronic packaging for aerospace devices due to its high reliability. However, its creep resistance is poor and can be improved by adding alloying elements. The effects of Sb content on the microstructure, tensile, and creep properties of eutectic SnPb solder were investigated. Sb addition effectively improved the mechanical properties of the SnPb solder. When Sb content exceeds 1.7 wt.%, SbSn intermetallic compounds (IMCs) occurred. And increasing the Sb content increased the tensile strength. Furthermore, Sb addition decreased the steady-state creep rate and increased the stress exponent n, suggesting that the creep resistance had been enhanced, which may be attributed to the hindrance of dislocation movement by SbSn IMCs, as well as the reduction in phase boundaries, which consequently reduced grain boundary sliding.

Preparation and soldering performance of SAC305@Sn-bi Core-shell solder balls based on eutectic co-deposition

SnBi eutectic thin film alloys are widely used in microelectronic devices, sensors, biomedical devices due to their high resistance, low temperature coefficient, chemical stability, and biocompatibility. However, the large standard electrode potential difference (454 mV) between Sn (−0.136 V) and Bi (+0.3118 V) makes them difficult to be co-deposited, especially with eutectic composition. In this study, cathodic polarization curves were used to analyze the negative shift of the cathodic reduction potentials of Sn and Bi induced by gelatin and EDTA-2Na, respectively, which reduced the potential difference between the two to 184 mv (Sn:-0.958 v; Bi:-0.774 v) and enabled the co-deposition of Sn and Bi; cathodic overpotentials were analysed to show that catechol not only improves the degree of cathodic polarization, but also raises the overpotentials, resulting in flatter surface coatings; By adjusting the temperature, current density, and pulse current, a SnBi eutectic thin film coating with good weldability, controllable thickness, flat surface, density, and uniformity was obtained on copper foil using a platinum as the anode in a methanesulfonic acid solution. The results indicate that it is feasible to deposit SnBi solder alloy at eutectic points (Sn41.53Bi58.47, At.%). Under the synergistic effect of gelatin and unidirectional square wave pulse, a typical eutectic network morphology can be obtained, which is the same as the microstructure of industrial SnBi eutectic solder. Based on these, a core-shell composite soldering material for low-temperature soldering was obtained by using SAC305 solder balls as cores and a SnBi low-temperature soldering material coating was roll-plated on their surfaces. This study provides a reliable technical way and theoretical guidance for low-temperature soldering, preparation of low-temperature solderable core-shell composite soldering material, and application of sensors and optoelectronic devices.

Influence of doping Si3N4 nanoparticles on the properties and microstructure of Sn58Bi solder for connecting Cu substrate

Purpose This study aims to explore the feasibility of adding Si3N4 nanoparticles to Sn58Bi and provides a theoretical basis for designing and applying new lead-free solder materials for the electronic packaging industry. Design/methodology/approach In this paper, Sn58Bi-xSi3N4 (x = 0, 0.2, 0.4, 0.6, 0.8, 1.0 Wt.%) was prepared for bonding Cu substrate, and the changes in thermal properties, wettability, microstructure, interfacial intermetallic compound and mechanical properties of the composite solder were systematically studied. Findings The experiment results demonstrate that including Si3N4 nanoparticles does not significantly impact the melting point of Sn58Bi solder, and the undercooling degree of solder only fluctuates slightly. The molten solder spreading area reached a maximum of 96.17 mm2, raised by 19.41% relative to those without Si3N4, and the wetting angle was the smallest at 0.6 Wt.% of Si3N4, with a minimum value of 8.35°. When the Si3N4 nanoparticles reach 0.6 Wt.%, the solder joint microstructure is significantly refined. Appropriately adding Si3N4 nanoparticles will slightly increase the solder alloy hardness. When the concentration of Si3N4 reaches 0.6 Wt.%, the joints shear strength reached 45.30 MPa, representing a 49.85% increase compared to those without additives. A thorough examination indicates that legitimately incorporating Si3N4 nanoparticles into Sn58Bi solder can enhance its synthetical performance, and 0.6 Wt.% is the best addition amount in our test setting. Originality/value In this paper, Si3N4 nanoparticles were incorporated into Sn58Bi solder, and the effects of different contents of Si3N4 nanoparticles on Sn58Bi solder were investigated from various aspects.

Investigating the preferential growth of Bi grains in Sn-Bi based solder under thermal aging

SnBi based solders have attracted widespread attention due to their promising applications in heterogeneous integration and three-dimensional microelectronic packaging. However, the low melting point of SnBi based solder means their high homologous temperature during service, leading to fast coarsening of the microstructure, which can significantly impair the reliability of electron devices. It has been found that Bi grains in SnBi based solder interconnects grow significantly and exhibit a preferred orientation under thermal loading conditions, but the mechanisms underneath the preferential growth of Bi grains is yet to be understood. In this work, a phase field model incorporating the thermal stress effect is developed and employed to investigate the dynamic evolution of the microstructure of SnBi solder under thermal aging, and to capture the morphology changes of the grains with different orientations. It is demonstrated that Bi grains with c-axis parallel to the z-axis preferentially exist in eutectic SnBi solder under thermal aging, and Bi grains with a large angle between the c-axis and the z-axis are swallowed by the preferred grains. Moreover, there is a competitive evolution between grains with different orientations in the polycrystalline eutectic SnBi solder, due to the minimization of system elastic strain energy. Further mechanism analysis elucidates that the Bi grain orientation preference in SnBi solders is caused by the dependence of their Young’s modulus and coefficient of thermal expansion on the grain orientation, the favored grains possess a lower strain energy compared to other grains.

The design of low-temperature solder alloys and the comparison of mechanical performance of solder joints on ENIG and ENEPIG interface

In recent years, in order to adapt to the trend of low-temperature assembly and integration, low-temperature hybrid solders with multiple elements added to the tin solder matrix have been investigated. In this regard, the morphology and size of intermetallic compounds (IMCs) are altered by adding some alloying elements, and the strength of solder joints is improved to some extent. Different pad surface treatments affect the growth of IMC, which leads to various failure modes in interconnect solder joints. Therefore, it is necessary to study the interfacial reaction, microstructure and mechanical properties of hybrid solder and different metal pads to explore the growth mechanism of IMC and the failure modes of solder joints. In this paper, mixed Sn–3Ag-0.5Cu/Sn–58Bi low-temperature solder joints on Au/Ni/Cu (ENIG) and Au/Pd/Ni/Cu (ENEPIG) substrates are investigated. The results show that the addition of palladium element can change the IMC morphology, refine the grain size of the hybrid solder joints, and affect the fracture failure mode of the solder joints under shear force. The average shear strength is significantly higher than that of solder joints with ENIG surfaces under different process parameters. Thermodynamic calculations of enthalpy change and the effect of Jackson's parameter α value on IMC morphology are also investigated in this paper. The addition of palladium elements increases the α value and is more favorable to the formation of columnar grains. This provides guidance for the grain growth of IMC in hybrid solder joints with added alloying elements.

Effects of In addition on microstructure and properties of SAC305 solder

In powderswith different contents (0.5−10 wt.%)were melted into the Sn−3.0Ag−0.5Cu (SAC305) solder to change the microstructure and thus improve the properties of the solder. The results showed that β-Sn(In), Ag3(Sn,In) and Cu6(Sn,In)5 phases existed in all the In-added solders, and an additional phase of InSn4 was found in the SAC305−10In solder. With increasing In addition amount, the β-Sn nucleation sites were increased and the nucleation model was changed from {101} to {301}, which refined the β-Sn grains and transformed the β-Sn morphology from large grains to interlaced grains and finally to multiple grains. As a result, a combined effect of fine grain strengthening and solid solution strengthening was achieved to increase the microhardness of the SAC305−xIn solders with increasing In addition amount.

Current-induced solder evolution and mechanical property of Sn-3.0Ag-0.5Cu solder joints under thermal shock condition

Solder joint reliability suffers great challenges due to high current density and miniature solder bump diameter of electronic packages at cryogenic temperature. To tackle these issues, the solder microstructure evolution and the corresponding failure mechanism should be emphasized. In this study, the current-induced microstructure characteristics and mechanical behavior of Sn-3.0Ag-0.5Cu (SAC305) solder joints during thermal shock process was thoroughly addressed over cycles by combining diffusional, electrical, thermal and mechanical features. This result verified that the combining method of thermal shock and electromigration (EM) contributed to the atom diffusion and high thermal stress formation, further causing intermetallic compound (IMC) growth, the repaid dissolution of Cu pad and high thermal stress of the solder joints. High stress induced by either the thermal expansion mismatch of different component, large temperature change (ΔT =346 ℃) and severe lattice distortion became the direct reason for twins and cracks formation of SAC305 solder joints. The combination of crack propagated along the interface and the quick dissolution of Cu substrate at the corner accelerated the eventually failure of the solder joints. Moreover, as the thermal chock cycles was extended, the initiation and propagation of cracks at the cathode side weaken the cathodic shear strength. High stress-induced twin formation at the interface effectively moderated the shear strength degradation due to anode IMC growth after 9 cycles. This study contributed to thoroughly grasp the failure mechanism of the solder joints and design the twin-strengthened Sn-based solder joints under the coupling effects of extreme temperature variation and current stressing.

Effect of Si3N4 nanowires doping on microstructure and properties of Sn58Bi solder for Cu bonding

PurposeThe purpose of this study is to delve into the mechanism of Si3N4 nanowires (NWs) in Sn-based solder, thereby furnishing a theoretical foundation for the expeditious design and practical implementation of innovative lead-free solder materials in the electronic packaging industry.Design/methodology/approachThis study investigates the effect of adding Si3N4 NWs to Sn58Bi solder in various mass fractions (0, 0.1, 0.2, 0.4, 0.6 and 0.8 Wt.%) for modifying the solder and joining the Cu substrate. Meanwhile, the melting characteristics and wettability of solder, as well as the microstructure, interfacial intermetallic compound (IMC) and mechanical properties of joint were evaluated.FindingsThe crystal plane spacing and lattice constant of Sn and Bi phase increase slightly. A minor variation in the Sn58Bi solder melting point was caused, while it does not impact its functionality. An appropriate Si3N4 NWs content (0.2∼0.4 Wt.%) significantly improves its wettability, and modifies the microstructure and interfacial IMC layer. The shear strength increases by up to 10.74% when adding 0.4 Wt.% Si3N4 NWs, and the failure mode observed is brittle fracture mainly. However, excessive Si3N4 will cause aggregation at the junction between the solder matrix and IMC layer, this will be detrimental to the joint.Originality/valueThe Si3N4 NWs were first used for the modification of lead-free solder materials. The relative properties of composite solder and joints were evaluated from different aspects, and the optimal ratio was obtained.

The Microstructural, Mechanical and Electrical Properties of Pb-Sn and Lead-Free SC0.7 Solders Containing Sub Micron Active Carbon Particles

Soldering is performed in order to easily assemble electronic components and also to provide electrical conductivity. The strengths, hardness, physical properties and electronic properties of the solders, i.e. reduced energy loss, hardness, melting point and longer service life, can be achieved when their usage is improvised by the help of necessary alloying or neutral additions. In this study, the effect of the addition of sub micron sized activated carbon on the mechanical, physical and electrical properties of industrially used solders, i.e. Pb-Sn and lead free SC0.7 solder was investigated.The thermal studies showed that the melting point of Pb-Sn was lowered against lead free solders with increasing amount of activated carbon. The tensile shear strength of both solders did not improve with increasing amount of activated carbon. In lead-free solders, the electrical resistance values decrease with respect to increasing active carbon ratio, however, the resistance of Pb-Sn solders increased. The addition of active particles have positively affected the microstructure of Pb-Sn solders, resulting in a finer grains, whereas, the addition of active carbon particles have no effect on the grain structures of lead free solder.

Effect of the addition of CeO2 nanoparticles on the microstructure and shear properties of Sn–57Bi–1Ag solder alloy

In this study, different weight fractions (0, 0.2, 0.5, 0.7, and 1.0 wt%) of cerium oxide (CeO2) nanoparticles were used to enhance the properties of Sn–58Bi–1Ag (SBA) solder alloys. As expected in the design, the CeO2 nanoparticles are diffusely distributed in the solder matrix. The microstructure evolution, growth of intermetallic compound (IMC) at the interface, and shear properties of the composite solder were systematically investigated using a scanning electron microscope (SEM) equipped with energy-dispersive X-ray spectroscopy (EDS) and electron backscatter diffraction (EBSD) probes. The results showed that adding an appropriate amount of CeO2 nanoparticles can refine the microstructure of the composite solder. Many β-Sn twin structures were observed in the SBA-0.5CeO2 and SBA-0.7CeO2 solder matrix, bringing better deformability to the β-Sn phase and improving the plasticity of the solder matrix. Moreover, with the addition of nanomaterials, there was a notable decrease in the thickness of the interfacial IMC layer of the solder/Cu joint, accompanied by a refinement in the grain size of the IMC. To our satisfaction, the addition of CeO2 nanoparticles in the appropriate proportion exhibited a remarkable enhancement in both shear strength and toughness of the composite solder alloys, working in tandem to transform the fracture mechanism from a purely brittle mode to a mixed mode of ductility and brittleness. It is indicated that the doping of CeO2 improves the reliability of SBA solder, potentially paving the way for a novel approach to particle-enhanced modification of Sn–Bi–Ag-based low-temperature solders.

Investigation of Microstructure and Mechanical Properties of SAC105 Solders with Sb, In, Ni, and Bi Additions.

Low Ag lead-free Sn-Ag-Cu (SAC) solders have attracted great interest due to their good drop resistance, high welding reliability, and low melting point. However, low Ag may lead to the degradation of the mechanical properties. Micro-alloying is an effective approach to improving the properties of SAC alloys. In this paper, the effects of minor additions of Sb, In, Ni, and Bi on microstructure, thermal and mechanical properties of Sn-1 wt.%Ag-0.5 wt.%Cu (SAC105) were systematically investigated. It is found that the microstructure can be refined with intermetallic compounds (IMCs) distributed more evenly in the Sn matrix with additions of Sb, In, and Ni, which brings a combined strengthening mechanism, i.e., solid solution strengthening and precipitation strengthening, leading to the tensile strength improved of SAC105. When Ni is substituted by Bi, the tensile strength is further enhanced with a considerable tensile ductility higher than 25%, which still meets the practical demands. At the same time, the melting point is reduced, the wettability is improved, and the creep resistance is enhanced. Among all the investigated solders, SAC105-2Sb-4.4In-0.3Bi alloy possesses the optimized properties, i.e., the lowest melting point, the best wettability, and the highest creep resistance at room temperature, implying that element alloying plays a vital role in improving the performance of SAC105 solders.