Eutectic Solder Research Articles

Pb Segregation in SnPb eutectic solder alloy induced by gamma irradiation

Pb segregated and formed a Pb segregation area in SnPb eutectic solder joint after 100 h of gamma irradiation. With the irradiation time increased to 150 h, Pb segregating stopped. The Pb segregation was attributed to the oxidation of β-Sn to SnO2 induced by the gamma irradiation. The Pb element content in the segregation area predicted by the segregation heat formulas is 53.5 %, which is consistent with the experimental result of 49.11 %. Density functional theory (DFT) calculation and Molecular dynamics (MD) simulation results were used to prove that the Pb segregation is caused by the oxidation of β-Sn.

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.

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.

Pseudo lamellae of Cu6Sn5 on the crystal facet of Sn in electrodeposited eutectic Sn-Cu lead-free solder

Eutectic Sn-Cu lead-free solder is developed using the pulse electrodeposition method from a citrate bath at different current densities like 0.1, 0.2, 0.4, and 0.5 A/cm2. The exact composition of all the deposits was confirmed through atomic absorption spectroscopy (AAS) analysis. The coating deposited at 0.2 A/cm2 constitutes 0.7 wt% of Cu which is similar to the eutectic Sn-Cu composition. Microstructural characterization was carried out with the help of a scanning electron microscope (SEM). Sn was the major constituent in all the deposits while a little amount of intermetallic i.e. Cu6Sn5 was present for the deposits at 0.1 and 0.2 A/ cm2. The energy dispersive spectroscopy (EDS) results showed traces of Cu6Sn5 in the deposits. The formation of Cu6Sn5 was also confirmed through X-ray diffraction (XRD). For the deposit at 0.2 A/cm2, the endothermic peak temperature in DSC is exactly the same as that of the melting point of Sn-Cu eutectic. This electrodeposited microstructure resembles the conventional eutectic Sn-Cu cast structure. The top view of the deposited Cu6Sn5 on the steps of Sn creates an illusion of lamellar structure. The effect of current density on the roughness was analyzed through AFM.

Composite soldering materials for high-temperature stable solder joints

The thermal load on electronic assemblies is constantly increasing. The reasons for this increase are, on the one hand, the integration of power electronic components in an ever smaller space and thus an increasing power density and, on the other hand, the increasingly harsh environmental conditions with high temperature load. In addition to electronic components and substrate materials, the soldered connections are also exposed to this stress and must withstand it. The thermal stability is primarily determined by the melting temperature of the solder material or by the remelting temperature of the final solder interconnection. The remelting temperature can be purposefully increased through diffusion soldering. The advantage of diffusion soldering is that the operating temperature of the final solder joint can exceed the joining process temperatures. By using the composite soldering materials and diffusion soldering process it is possible to produce the solder interconnections that can withstand the high thermal and thermomechanical stress [1]. In this work, the composite solder material, consisting of the base solder alloy BiSnAg in eutectic composition with a melting point of 139 °C and added copper particles, was examined. The added copper particles have a direct influence on the dynamics of the diffusion process. Diffusion can also be influenced by adjusting the soldering process parameters, such as maximum temperature and time above liquidus of the base solder alloy, with the aim of achieving isothermal solidification. The solidification can take place through the parallel reactions: the reaction between tin and copper with the formation of high-melting intermetallic phases Cu3Sn and Cu6Sn5 and the growth of bismuth crystals through coarsening of the structure and tin depletion in the original eutectic solder alloy [2].

Effect of gamma irradiation on microstructural evolution and mechanical properties of SnPb eutectic solder joints

Eutectic SnPb ball grid array (BGA) solder joints were exposed to 60Co source gamma irradiation at a dose rate of 1 Gy(Si)/s from 0, 50, 100, 150 and 200 h in air. The effects of gamma irradiation on the microstructure evolution and mechanical properties of the solder joints were investigated. After irradiation, β-Sn and Pb on the surface of the solder joint was oxidized to SnO2, PbO and PbO2, and an oxide layer covered with Cu oxide was formed on the surface of the solder joint. The formation process and mechanism of the oxide layer were analyzed. Sn and Pb depletion holes and Cu depletion areas appeared on the solder joint surfaces after various irradiation time. SnO2 nanocrystals and Sn wrinkles appeared in the FIB specimen after irradiation. After 200 h of irradiation, the melting temperature of the SnPb eutectic solder alloy decrease, and the shear force value of the solder joint first increase and then decrease.

Evaluation of the microstructure, thermal, and mechanical characteristics of Sn-9Zn reinforced with Ni and ZrO2 nanoparticles via vacuum melting process

The impact of minor additions of nickel and ZrO2 nanoparticles to eutectic Sn-9wt%Zn (SZ) prepared by vacuum melting technique was investigated. The morphologies and microstructures were carried out using an optical microscope (OM) and field emission scanning electron microscope technique (FESEM) escorted by energy dispersive x-ray spectrometry (EDX). The phase structure of the specimens was confirmed by an x-ray diffractometer (XRD). The results obtained demonstrate that small Ni addition causes a major grain refinement of β-Sn, due to the formation of the fine intermetallic compounds Ni5Zn21 and Sn3Ni4Zn3 phases and refines the formation of α- Zn lamellar phase. The melting temperature of the recently discovered solder alloys was lower than that of the eutectic Sn-Zn solders (∆Tm ∼ 28 °C) as a result of the preparation technique and the incorporation of Ni and ZrO2 nanoparticles. The tensile test showed enhanced the mechanical properties of SZ solder as a result of the addition of third elements. The experimental results showed that of all the alloys under investigation, the SZN903 alloy had the greatest UTS and YS values. The enhanced strength of the SZ-ZrO2 alloy defended the results of σ UTS and increased the stress exponent parameters, n, by ∼20%. All solders had an activation energy Q that measured between ∼35.62 kJ mol−1 to ∼58.12 kJ mol−1 which comparable to the pipe-diffusion mechanism.

Interfacial Properties of Sn-Cu-xCr Alloy using Laser-Assisted Bonding

Conventional hot air reflow soldering is one of major bonding technology when bonding is proceeded on automotive electronics applications. However, here we focus on modifying the bonding process and composition of solder to enhance mechanical and thermal properties. This study experimentally investigated the mechanism of how laser-assisted bonding (LAB) form a small size of initial intermetallic compounds (IMC), and 0.2 wt% Cr element was added to Sn-0.7Cu eutectic solder to suppress the IMC growth. As a result, Sn-0.7Cu and Sn-0.7Cu-0.2Cr initial grain refinement was achieved by LAB. Isothermal aging was conducted to observe the mechanical and thermal properties depending on the IMC growth under 100, 125, 150 ℃ respectively. Sn-0.7Cu-0.2Cr tended to inhibit the growth of IMC at solder matrix and interface compared to Sn-0.7Cu throughout all aging temperature and time. The shear test was proceeded and Sn-0.7Cu-0.2Cr shear force was achieved 18% higher than Sn-0.7Cu. Even after isothermal aging, Sn-0.7Cu-0.2Cr showed lower reduction rate of shear force compared to Sn-0.7Cu.

Microstructure evolution in undercooled Ag-50at. %Cu hypereutectic alloy

Ag–Cu alloys, as one type of typical eutectic solders, have been widely used in microelectronic packaging. The welding performance of Ag–Cu solders is closely associated with their microstructures. However, the microstructure evolution of Ag–Cu alloys during solidification is still poorly understood. In this work, a new melt fluxing technique was proposed to investigate the microstructure evolution of undercooled Ag-50at.%Cu hypereutectic alloy. The maximum undercooling of Ag-50at.%Cu alloy can reach up to 135 K. The obtained results show that the microstructures consist of primary dendrite and lamellar eutectic at low undercooling (ΔT – 10 K). With the increase of undercooling, dendrites undergo refining (ΔT < 65 K) and then disappear completely (ΔT = 78 K) and appear again (ΔT = 119 K). It is also discovered that cellular lamellar eutectics formed with ΔT within range of 65 K–78 K. Unexpectedly, irregular microstructures are observed when ΔT > 135 K. Theoretical calculation results indicate that the formation of irregular eutectic is associated with the dendritic fragmentation and eutectic coarsening under larger undercooling (ΔT = 135 K). These results not only elucidate the relationship between the solidification microstructure and undercooling of Ag-50at. %Cu hypereutectic alloys but also has positive significance for other hyper-eutectic systems.

Significant enhancement of comprehensive properties of SnBi solder through the addition of Cu@Ag core-shell particles

As a critical low-temperature lead-free solder, SnBi eutectic solder was known for its abundant lamellar structures of Bi-rich phase, which often resulted in problems such as brittleness, low electrical conductivity, and low thermal conductivity. In this study, a method was introduced to enhance the comprehensive properties of SnBi solder by adding Cu@Ag core-shell particles. Our results revealed that the modified SnBi solder exhibited significant refinement in both grain size and intragranular eutectic structures, resulting in a shift from the original brittle fracture mode to a mixed brittle and tough mode and a consequent increase in tensile strength by 21%. Moreover, the modified solder demonstrated a significant 59% increase in electrical conductivity by forming interconnected highspeed channels for electron migration. In addition, the addition of Cu@Ag core-shell particles to SnBi solder resulted in remarkable contributions of both electrons and phonons to thermal conductivity, with its value of 41.33 W m−1 K−1. Our research addressed partial property deficiencies of SnBi solder, which could be valuable in expanding its application in low temperature electronic packaging.

Effect of Au thin films thickness on the wetting characteristics of eutectic Pb-Sn solder on Ni/Ag solder bath

Wetting of Pb-Sn solder on Au/Ni surface is experimentally studied as a function of the thickness of Au coating on Ni buffer layer. While Au coating is known to increase the wettability of Pb-Sn solder on Ni surface, the effect of Au layer thickness was not examined systematically. This study shows that i) an increase in Au layer thickness from 0.15 to 0.3 µm decreases the surface coverage (spread) of the solder and ii) there is a compositional change in Pb-Sn solder on Au/Ni surface due to formation of a Sn rich region at the solder - Ni interface during a reflow process of the solder. The thickness of Sn rich region near the interface increases with increasing the Au layer thickness. A driving force for the formation of the Sn rich phase is explained using the negative mixing enthalpy of Au-Sn. Since an increase in the Sn content of Pb-Sn solder increases the surface energy and viscosity of the solder melt, an increase in the thickness of the Sn rich region at the solder-Ni interface suppressed the wetting of the solder.

Role of Cu percentage in the Sn-xCu alloy on the mechanical performance at Sn-xCu/ENIG interface produced by laser soldering

PurposePb-free solders have been developed to replace the standard Sn–Pb eutectic solder since the prohibition on Pb used in solders. The Sn–Ag–Cu series of lead-free solders is the most extensively used in the electronics industry. The Ag3Sn, which forms during isothermal ageing, can significantly degrade solder joint reliability. Sn–Ag–Cu solder’s high price further hindered its use in the electronics industry. This paper aims to investigate different copper percentages into Sn–xCu solder alloy to improve its microstructure and strength performance.Design/methodology/approachThe solder alloys used in this work were Sn–xCu, where x = 0.0, 0.3, 0.5, 0.7, 1.0 Wt.%, which was soldered onto electroless nickel immersion gold (ENIG) substrate using carbon dioxide (CO2) gas laser. Then these samples were subjected to isothermal aging for 0, 200, 500, 1,000 and 2,000 h. The Sn–xCu solder alloy was fabricated through a powder metallurgy process.FindingsMicrostructure characterization showed that Cu addition resulted in fine and rounded shape of Cu–Sn–Ni particles. Shear strength of Sn–xCu solder joints was increased with increasing Cu content, but at aging duration of 1,000 h, it dropped slightly. It is believed that the strength improved due to the increment of diffusion rate during isothermal aging.Practical implicationsIn a Cu–Sn solder, the recommended amount is 1.0 Wt.% of Cu. In extensive aging procedures, it was discovered that Sn1.0Cu solder improved the reliability of solder joints. The findings indicated that the innovative solder alloys might satisfy the needs of high-reliability applications.Originality/valueThe study shows that the right amount of Cu enhances the solidification of Sn–Cu solder, increasing the shear force of the Cu–Sn solder joint. The Sn1.0Cu exhibits a ductile fracture on the top microstructure, improving the joint’s average shear strength.

Heterogeneous Integration of III-V Lasers in a 300 mm CMOS Manufacturing Line

AIM Photonics has developed a high precision laser attach process using an ultra-precise ASM Amicra NANO 300 mm die-to-wafer flip-chip bonder and integrated solder stamping system. Laser die are placed with high accuracy (&lt;1 µm) and soldered to form a AuSn eutectic bond. This photonic platform has low optical losses, with SiN waveguides measuring on the order of 0.4 dB/cm and a calculated laser-to-waveguide coupling loss of 1.86 dB.

A High-Sensitivity Resonant Differential Pressure Microsensor Based on Wafer-Level Eutectic Bonding

This article presented a high-sensitivity resonant differential pressure microsensor based on wafer-level eutectic bonding, where dual resonators were embedded in the pressure-sensitive diaphragm to sense differential pressures, and a silicon cap was used to form a vacuum cavity. Differential pressures applied to the developed microsensor caused deflections of the pressure-sensitive diaphragm, resulting in shifts in resonant frequencies. This microsensor was designed based on finite element simulations with optimized structural parameters, which indicated high differential pressure sensitivities. Micro fabrications with key processes of deep reactive-ion etching (DRIE), lithography, and wafer-level eutectic bonding were adopted for device fabrication. The following experimental characterizations were conducted, producing the differential-pressure sensitivity of 181.53 Hz/kPa, the maxing fitting error of less than 80 Pa, under the differential pressure range of 0–100 kPa, the static pressure range of 110–200 kPa, and the temperature range of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$-$</tex-math> </inline-formula> 10 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$^{\circ}$</tex-math> </inline-formula> C to 60 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$^{\circ}$</tex-math> </inline-formula> C. These results show that developed resonant differential pressure microsensors have excellent performances for differential-pressure measurements.

Physics of failure based lifetime modelling for sintered silver die attach in power electronics: Accelerated stress testing by isothermal bending and thermal shock in comparison

The employment of sintered silver (SAG) as die attach material is one of the most promising solutions to utilize the advantages of wide bandgap semiconductors in modern power electronic packaging. Its electrical, thermal and mechanical – i.e. reliability correlated – properties are far superior to those of time honored eutectic solders. To master the challenges of a high-quality production on an industrial level in accordance with the ever increasing application-driven reliability requirements, SAG die attach technology has to be developed, tested and lifetime-modelled in the context of a design for reliability approach, in order to be understood and thus savely put into application in the field. This requires the use of modern physics-of-failure paradigms, as today’s mostly used empirical lifetime models are meeting their limits with power electronics becoming more diverse in all relevant determinants such as materials, packaging technologies, geometric dimensions and reliability requirements. Introduced will be an isothermal bending test (ITBT) as highly accelerated, simple but very insightful test mimicking the power cycling load regime. This test will be combined with a physics of failure based approach, which will be presented including material characterization, modelling, simulation and definition of a failure parameter. This test method has the potential to produce reliability results much faster than non-mechanical tests, while the physical failure parameter still allows transferability of the resulting model. We show for the first time a physics-of-failure based lifetime model for SAG using isothermal bending in comparison with thermal shock test. For this we used the total inelastic strain (including plastic, primary and secondary creep) as local failure parameter for die attach degradation by fatigue crack growth.

English

Diffusion processes on the contact areas of the metal-solder-semiconductor system are experimentally studied in this work. Diffusion coefficients, activation energies and pre-exponential factors in samples commutated with solders based on Pb-Sb are determined. It has been established that lead-based solder has a significantly higher inertness to thermoelectric materials. The nickel-phosphorus coating was coated with a nickel-phosphorus coating according to the method described for copper busbars. Thermocouple legs and tire blanks were tinned with Pb - Sb eutectic solder. After tinning, the branches of the thermocouples of 2 &times; 2 &times; 4 mm and 3 &times; 3 &times; 4 mm dimensions were cut by electric spark cutting and soldered together with the conductor grids. Experimental verification of the obtained results was carried out by manufacturing and testing a cooling thermopile at high temperatures in individual half-cells. Key words: Diffusion, alloy, thermoelement, solder, contact, thermopile, activation energy, chemical activity.

An All-Silicon Resonant Pressure Microsensor Based on Eutectic Bonding

In this paper, an all-Si resonant pressure microsensor based on eutectic bonding was developed, which can eliminate thermal expansion coefficient mismatches and residual thermal stresses during the bonding process. More specifically, the resonant pressure microsensor included an SOI wafer with a pressure-sensitive film embedded with resonators, which was eutectically bonded with a silicon cap for vacuum encapsulation. The all-Si resonant pressure microsensor was carefully designed and simulated numerically, where the use of the silicon cap was shown to effectively address temperature disturbances of the microsensor. The microsensor was then fabricated based on MEMS processes where eutectic bonding was adopted to link the SOI wafer and the silicon cap. The characterization results showed that the temperature disturbances of the resonant pressure microsensor encapsulated with the silicon cap were quantified as -0.82 Hz/°C of the central resonator and -2.36 Hz/°C of the side resonator within a temperature range from -40 °C to 80 °C, which were at least eight times lower than that of the microsensor encapsulated with the glass cap. Compared with the microsensor using the glass cap, the all-silicon microsensor demonstrated an accuracy improvement from 0.03% FS to 0.01% FS and a reduction in short-term frequency fluctuations from 3.2 Hz to 1.5 Hz.

Study of diffusion processes in contact areas of thermocouples with metals

Diffusion processes on the contact areas of the metal-solder-semiconductor system are experimentally studied in this work. Diffusion coefficients, activation energies and pre-exponential factors in samples commutated with solders based on Pb-Sb are determined. It has been established that lead-based solder has a significantly higher inertness to thermoelectric materials. Humans are currently facing complex challenges such as rising energy costs, pollution and global warming. To reduce their consequences, scientists are concentrating on improving power generators focused on energy harvesting. Thermoelectric generators (TEGs) have demonstrated their ability to convert thermal energy directly into electricity through the Seebeck effect. Due to the unique advantages, they present, thermoelectric systems have emerged over the past decade as a promising alternative among other technologies for the production of clean energy. [1-11]. Switching is the most time-consuming and responsible operation in the manufacture of thermoelectric modules. In them, which include a significant number of junctions, failures most often occur due to broken contacts [2-8]. To prevent the harmful effects of internal mechanical stresses, in the manufacture of thermoelectric batteries, it is necessary to use a damping layer between the branch and the connecting plate [3-14]. The damping layer is made of a material with sufficient plasticity and low ohmic resistance. It is usually made from lead. The results of the research showed the advantages of using a single -wire technology for soldering with Pb - Sb eutectic solder using an anti -diffusion layer of chemically deposited nickel. In this case, the eutectic solder Pb - Sb in the contact simultaneously performs the role of a damper and a switching solder.

Reliability of laser soldering using low melting temperature eutectic Sn Bi solder and electroless Ni-electroless Pd-immersion Au-finished Cu pad

The demand for flexible wearable devices/substrates with miniaturization and improved integration in microelectronic devices has intensified the research interest in low-temperature laser soldering processes as an alternative to conventional reflow soldering processes owing to their advantages, such as local heating, non-contact heating, and short bonding time. In this study, we compared and evaluated the reliability of laser soldered and conventional reflow soldered joints using representative low melting temperature eutectic Sn Bi solder and thin electroless Ni-electroless Pd-immersion Au (ENEPIG)-finished Cu pads. Laser soldering was performed using various laser powers (130, 150, and 170 W) and times (2 and 4 s). Furthermore, an aging test was performed at 110 °C for 2000 h to evaluate the long-term reliability of the soldered joints. The mechanical properties, including the top and cross-sectional views and fracture surfaces, of the soldered joints were analyzed by conducting shear tests after aging. During laser soldering, various intermetallic compounds (IMCs) were formed at the joints depending on the applied energy. The metallization layer and Cu reacted with Sn in the solder after different aging durations, and additional IMCs were formed and grown. After aging for 2000 h, the shear strength decreased, and the interfacial IMC thickness increased. As the aging time increased, the fracture mode changed from an initial ductile fracture to brittle fracture (between the solder and IMCs and/or between IMCs and the Cu pad). The reflow soldered joints exhibited stable shear strength, resulting in ductile fracture until aging for 500 h. However, the shear strength decreased sharply after aging for 1000 and 2000 h, and Bi-segregation was observed after aging for 1000 h, resulting in inferior long-term reliability. After laser soldering at 150 and 170 W for 4 s, the strength of the samples decreased sharply after aging for 1000 and 250 h, respectively, and Bi-segregation was observed after aging for 2000 h. The shear strength of the sample laser soldered at 170 W for 2 s gradually decreased with increasing aging time and maintained a stable shear strength until aging for 2000 h. Therefore, laser soldering at 170 W for 2 s was considered as the optimal condition for long-term reliability. • Soldering properties of laser soldered Sn-58Bi/Au/Pd/Ni-finished Cu joints evaluated. • Laser soldering results were compared with conventional reflow soldered joints. • Various IMCs were formed depending on laser power and irradiation time. • Laser conditions with low applied energy displayed superior long-term reliability. • Selection of the optimal laser conditions is crucial to ensure reliable solder joints.