Intermetallic Compound Growth Research Articles

Improved Cu/Sn interface reliability using double-layer stacked nano-twinned Cu

The immoderate growth of intermetallic compound (IMC) at the Cu/Sn bonding interface reduces the reliability of bonding joints, leading to the failure of high-density packaging. Herein, we design a double-layer nanotwinned Cu (d-ntCu) structure composed of the perpendicularly aligned nano-twinned Cu (p-ntCu) as the upper layer and horizontally aligned nano-twinned Cu (h-ntCu) as the lower layer. We study the Cu/Sn bonding interface microstructure evolution to reveal the IMC growth inhibition and void suppression ability of d-ntCu. As a comparison, the interface microstructure evolution of single layer h-ntCu/Sn is also studied. After thermal aging, the growth mode of IMC at the Cu/Sn bonding interface can be divided into two stages, which are caused by the in-situ annealing of the p-ntCu. In the initial stage of aging, the main diffusion path of Cu atoms is twin boundary diffusion, causing a rather fast growth of IMC. After 100 h aging, the twins anneal into large grains, which induce a lower growth rate of IMC due to the bulk diffusion of Cu atoms. Compared with the h-ntCu single layer, the IMC thickness of the d-ntCu is suppressed by 20%. Besides, the bonding interface in d-ntCu/Sn is void-free due to the vacancy-sink effect of twin boundaries. Therefore, using d-ntCu as the substrate can not only control the IMC growth rate but also suppress the formation of voids during aging, which is helpful to achieve high bonding reliability.

Study on Ni-GNSs enhanced Sn2.5Ag0.7Cu0.1RE/Cu solder joints β-Sn grain orientation and interfacial IMC growth kinetics under constant temperature thermomigration

Aiming at the thermomigration problem caused by the large temperature gradient (TG) of micro-soldering joints, a constant temperature thermomigration device with temperature control function was designed and manufactured. This paper studied the polarity phenomenon, crystallographic characteristics, and interfacial intermetallic compound (IMC) growth kinetics of Ni-GNSs reinforced Sn2.5Ag0.7Cu0.1RE/Cu solder joints under thermomigration. The results indicate that Ni-GNSs reinforced Sn2.5Ag0.7Cu0.1RE/Cu solder joints exhibited a significant thermomigration polarity phenomenon under the conditions of TG ≥ 1000 °C/cm and θ ≤ 43.5° between the c-axis and TG of β-Sn grains. At the cold end of the solder joint, the Cu6Sn5 phase at the interface gradually thickens and forms Cu3Sn phase on the substrate side, while microcracks expanded and gradually developed into macrocracks. At the hot end of the interface, the Cu6Sn5 phase gradually dissolved. The growth of the Cu3Sn phase was accompanied by “Kirkendall voids” that formed cracks at the interface between the joint and the solder until a “fully IMC solder joint” was formed. The growth of Cu6Sn5 IMC at the solder joint interface came before that of Cu3Sn IMC. The average temperature and temperature gradient of the solder joint were correlated with the growth of Cu3Sn IMC, leading to the formation of interface Cu3Sn IMC due to the oversaturation of Cu atoms. The addition of 0.05 wt% Ni-GNSs refines the grain structure and increases the activation energy for the growth of Cu6Sn5 and Cu3Sn IMC at the cold end of the solder joint, suppressing the thermomigration polarity phenomenon.

In Situ Study the Grooving Effect Induced by Ag Particles on Rapid Growth of Cu6Sn5 Grain at Sn-xAg/Cu Soldering Interface during the Heat Preservation Stage

Synchrotron radiation X-ray imaging technique was applied for in situ observation of Cu6Sn5 intermetallic compounds (IMC) growth in Sn/Cu and Sn-3.5Ag/Cu joints under isothermal temperature conditions of 250/300/350 °C and time duration of 1.5 h. The IMC in Sn-Ag solder was characterized by the formation of grooves during the interfacial reaction, and this can be attributed to the Ag content. Kinetically, the growth rate constants for the height of Cu6Sn5 were observed to increase with temperatures and the presence of Ag in solder. As compared to pure Sn solders, the Sn-3.5Ag solders were observed with interfacial IMC of greater height, smaller base width, and lowered aspect ratio.

Microstructure Evolution and Growth of Interfacial Intermetallic Compounds in NiCr/Ti Alloy Laminated Composite after Explosive Welding and Heat Treatment

The paper considers the issues of interaction of the molten metal at the interface of explosively welded NiCr/titanium alloy laminated composites with the reaction zone formed during heat treatment, as well as the features of its destruction after welding. It was established that the molten metal is a heterogeneous mixture based on Ni(Cr,Ti) and Ti(Ni,Al) solid solutions and NiTi and Ni3Ti intermetallic compounds. The estimated existence time of molten metal areas in the liquid state was ~10−8–10−11 s. The obtained values are comparable with the time of the unloading wave arrival at the contact surface, which is the reason for the presence of fracture areas in the form of detachments on the fracture surface. Continuous nanometer-size interlayers with an amorphous structure, due to the ultra-high cooling rate of the liquid melt, induce viscous destruction of the interface. Heat treatment at temperatures of 700 and 850 °C led to the formation of a layered reaction zone at the NiCr/Ti boundary, consisting of interlayers of solid solutions based on Ti2Ni, TiNi, and TiNi3 intermetallic compounds, as well as inclusions of a Cr(Ti) solid solution. The diffusion flow gradient was predominantly directed into the titanium alloy.

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.

Research Progress of Palladium-Plated Copper Bonding Wire in Microelectronic Packaging.

Wire-bonding technology is the most commonly used chip interconnection technology in microelectronic packaging. Metal bonding wire is the key material for wire bonding and plays an important role in the reliability of electronic devices. In recent years, palladium-plated copper (PdCu) bonding wire has been widely used because of its low cost, good electrical and thermal conductivity, the fact that it is not easy to oxidize, and its high reliability. Therefore, it is necessary to review its research progress. In this paper, the preparation and application of palladium-plated copper bonding wire are reviewed. Firstly, the preparation methods of electroplating, electroless plating, and direct plating are introduced. Secondly, the factors affecting the distribution of Pd in free air balls and bonding interfaces, the effect of Pd on the formation and growth of intermetallic compounds in PdCu wire, stitch bond, and reliability of PdCu wire are summarized and analyzed in the application process. Finally, its development prospect is prospected. Hopefully, this review can help readers to have a comprehensive understanding of the preparation and application of palladium-plated copper bonding wires, and can accelerate the promotion of its application in more fields in the future.

Effects of Ag content on microstructure evolution, intermetallic compound (IMC) and mechanical behaviour of SAC solder joints

SnAgCu (SAC) solder joints are widely used in electronic industry as alternative to lead free solder. The microstructure of the solder joint plays an important role in enhancing the mechanical properties of the solder joint, thus the electronic devices will have a longer lifetime. This paper studies the effects of silver (Ag) percentage on the microstructure and intermetallic compound (IMC) in Sn-Ag-Cu solder, and how the addition of Ag impacts the mechanical concepts of SAC solder joints. SAC solder joints were examined as a function of Ag3Sn precipitates (in terms of the number and size of the precipitates) and intermetallic compounds (IMCs). The microstructure morphology of the SAC samples was analyzed by using a scanning electron microscope (SEM) with back scattering mode.A quantitative analysis of number of Ag3Sn was performed for all SAC samples. The results showed that when the amount of the Ag content increased, that led to an increase in the number of Ag3Sn precipitates with an increase the eutectic area but does not affect the growth of IMC. The mechanical properties of SAC samples were enhanced significantly by increasing the Ag content.

Study of microstructure, growth orientations and shear performance of Cu/Sn-3.0Ag-0.5Cu/Cu solder joints by using thermal gradient bonding

In this study, the effects of the thermal gradient (TG) applied during the bonding process on the microstructure, grain orientations and shear properties of Cu/SAC305/Cu solder joints were investigated, and the magnitude of the TG was controlled by the thickness of the solder layer. The results indicated that the introduction of TG caused the asymmetric growth of intermetallic compounds (IMCs) and enabled the rapid generation of IMCs at the cold end. Cu6Sn5, as the main component of IMCs in Cu/Sn solder joints, developed a strongly preferred orientation in the (0001) ‖ RD direction. While for β-Sn grains, the preferred orientation was uncontrollable, which formed the preferred orientations of (010) ‖ TD, (031) ‖ RD and (114) ‖ RD at 20 um, 60 um and 100 um solder joints, respectively. In addition, the TG reduced the reliability of solder joints whose shear properties were lower than those of joints with isothermal bonding.

The mechanism of Fe-rich intermetallic compound formation and growth on inoculants revealed by electron backscattered diffraction and X-ray imaging

Fe-rich intermetallics affect critically the mechanical properties and recyclability of aluminium alloys. Increasing effort has been spent on the inoculation of these intermetallics, hoping to promote a finer distribution. Recently Al-5Ti-1B (wt.%), originally developed to refine α-Al, has been shown to refine Al13Fe4, an intermetallic phase present in a variety of Al alloys. However, mechanisms of the formation and growth of the intermetallics on the inoculants are unclear. In this paper, Ti is added to Fe-containing Al alloys to produce a large number of potent Al3Ti particles, the active inoculant in Al-5Ti-1B. We use a combination of electron backscattered diffraction, in situ synchrotron X-ray radiography and post-solidification X-ray computed tomography to investigate the formation and growth of primary Al13Fe4 on Al3Ti inoculants, first in a model Al-Fe alloy, with key insights then confirmed in a high Fe-containing, recycled 6xxx alloy. Crystallographic orientation relationships between Al13Fe4 and Al3Ti are analysed comprehensively, and the formation and growth dynamics of Al13Fe4 on Al3Ti is also unveiled. A strong link is revealed between the formation of Al13Fe4 on Al3Ti and a twinning-related pseudo-symmetry of Al13Fe4. Finally, a potential strategy to refine both intermetallics and α-Al in recycled alloys with elevated Fe concentration is proposed.

Effect of multi-walled carbon nanotubes on the microstructure and properties of Sn-58Bi solder alloys

The influence of multi-walled carbon nanotube (MWCNT) content on the melting properties, wettability, microstructure, and intermetallic compounds (IMCs) of Sn-58Bi-xMWCNT (x = 0, 0.01, 0.02, 0.03, 0.05, and 0.10 wt.%) and the effects of MWCNT on the tensile strength of Cu/Sn-58Bi-xMWCNT/Cu solder joint were analyzed. The results show that MWCNT addition at a small trace amount into Sn-58Bi solder could increase the spreading area of Sn-58Bi solder, refine the solder matrix microstructure, inhibit the growth of interfacial IMCs, and significantly improve the tensile strength of Sn-58Bi solder joints. However, the melting point and melting range remained the same or slightly changed. The wettability of Sn-58Bi alloys increased first and then decreased with the addition of MWCNT. The spreading area and the tensile strength of solder joint were the maximum when the MWCNT content was 0.01 wt.%, and they were 42.23 mm2 and 50.07 MPa, respectively. The reason may be related to the improved microstructure of solder alloys and the morphology of IMCs due to MWCNT addition at trace level.

Effect of Vacuum Heat Treatment on the Microstructure and Tribological Property of Ti–6Al–4V Alloy with Cu Coating

The effect of vacuum heat treatment on the interface microstructure and tribological property of Cu‐coated Ti–6Al–4V alloy is investigated herein. After the vacuum heat treatment process, a diffusion layer is formed at the interface between the Cu coating and the Ti–6Al–4V substrate. The formed intermetallic compounds at the interface between the Ti–6Al–4V substrate and Cu coating are CuTi2, CuTi, Cu4Ti3, and β‐Cu4Ti. The activation energy of intermetallic compound growth in the diffusion zone of Cu‐coated Ti–6Al–4V is 126.0 kJ mol−1, and the pre‐exponential factor is 0.1 m2 s−1. The tribological properties of the Cu‐coated Ti–6Al–4V alloy are best when subjected to diffusion treatment at 700 °C for 300 min, with weight loss reduced by 58.2% compared to the Ti–6Al–4V alloy. The wear resistance of the Ti–6Al–4V alloy can be enhanced by Cu coating and vacuum diffusion heat treatment, and the formation of the Cu–Ti intermetallic compound contributes to this improvement. These findings offer new insights for further advancements in the tribological properties of titanium alloys.

Effects of Bi and Cu addition on mechanical properties of Sn9Zn alloy and interfacial intermetallic growth with Ni substrate

Sn9ZnxBixCu (x = 0, 1.0, 2.0, 3.0 and 4.0 wt%) solder alloys were prepared by adding different contents of Bi and Cu elements, and the effects of Bi and Cu addition on the mechanical properties, wettability, and interfacial intermetallic compound (IMC) layer were researched. The addition of Bi and Cu can significantly improve the mechanical properties and creep resistance of the alloy. When the addition of Bi and Cu reaches 2 wt%, small Bi phases are dispersed in the matrix, and moderate Cu5Zn8 phases appear, which strengthens the solder matrix. The ultimate tensile strength (UTS) of the Sn9Zn2Bi2Cu alloy reaches 51.01 MPa, which is 149.32% higher than that of the Sn9Zn alloy, and the elongation reaches 26.56%. Nanoindentation results show that the holding displacement of the Sn9Zn4Bi4Cu alloy decreased by 28.48% compared with that of the Sn9Zn alloy at a loading rate of 0.1 mN/s. In addition, proper addition of Bi and Cu can improve the wettability of the solder alloy and inhibit the growth of interfacial intermetallic compounds (IMCs) between the solder and Ni substrate. When the reflow time reaches 40 min (min), the interfacial IMC thickness of the Sn9Zn2Bi2Cu/Ni solder joint is 1.93 µm, which is 46.09% smaller than that of the Sn9Zn alloy. Moreover, the shear strength of the Sn9Zn2Bi2Cu/Ni solder joint increases by 33.3%, reaching the maximum value (38.76 MPa). When the Bi and Cu addition reaches 2 wt%, the wetting area reaches a larger value (13.525 mm2), which is 28.35% higher than that of Sn9Zn alloy.

Optimized designing of generalized electrodes for aluminum/steel resistance spot welding process based on numerical calculation

This work focused on the effects of using different electrode combinations on the welding process and welding quality during aluminum/steel resistance spot welding (RSW) process. The electrodes used during the RSW process can be classified into two catalogues, planar type (P type) and sphere type(S type). An effective two dimensional (2D) numerical calculation model using finite element method (FEM) was developed. In the model, the friction effects between different contact surfaces were seriously considered, and the accuracy and reliability of the model were verified by means of actual welding experiments. Subsequently, the numerical calculation model was used to determine which type of electrode combination was the best one for welding quality by analyzing corresponding RSW processes using four different electrode combination schemes: PP type, SS type, PS type and SP type for upper and lower electrodes. To guarantee scientific nature of the comparisons and analyses, a constant energy regulation method was introduced for each process. The heat energy generation analyses, intermetallic compound formation and growth analyses, and current density analyses were conducted. Combining with actual experiments, the results showed that the welded joint obtained from RSW process using SP type electrode combination scheme had the best comprehensive performance, not only in the double nugget sizes, but also in the deformations of two types of parent metal sheets. In addition, the optimum sizes of the electrodes in this combination were determined through numerical calculations and experiments. Final result showed that the optimum diameter for S type and P type were respectively 9 mm and 60 mm. The work can supply important references for the dissimilar metal RSW process improvement.

Effect of twin grain boundary on the diffusion of Cu in bulk β-Sn

For Cu is the dominant diffusing species in the Cu/Sn diffusion couple, the diffusion behaviors of Cu in the β-Sn grain and at the twin grain boundary (TGB) have been studied in this paper by combining the first-principles calculation and molecular dynamics simulation, which has a significant impact on solder joint reliability. The results show that the energy barrier for Cu bulk diffusion in β-Sn depends on the diffusion path, ranging from 0.01 eV to 0.33 eV. Among the three possible diffusion paths at the (101) TGB, the primary diffusion path is along the [010] direction of the TGB plane. However, this diffusion path along the TGB still presents a relatively high energy barrier of 0.26 eV compared to the energy barrier for bulk diffusion. Furthermore, due to the segregation of Cu atoms at the β-Sn TGB and the inhibition effect of multiple energy barriers for diffusion crossing the TGB, long-range diffusion of Cu across the TGB between the two β-Sn bulk grains is difficult. As a result, the (101) TGB actually inhibits the diffusion of Cu in β-Sn. It can be concluded that increasing the number of TGBs inside a Cu/Sn solder joint can effectively suppress the interdiffusion between Cu and Sn, which will prevent the growth of Cu-Sn intermetallic compounds and improve the reliability of the solder joint.

Interface evolution and strengthening of two-step roll bonded copper/aluminum clad composites

The laminated metal composite plate has drawn great focus in view of its advantages of high performance. In this study, a two-step roll bonded Cu/Al clad composites was developed. The micromorphology, components, mechanical properties, and interfacial bonding strength of the Cu/Al clad composites were characterized by scanning electron microscope (SEM), electron back scattered diffraction (EBSD), transmission electron microscope (TEM), energy dispersive spectrometer (EDS), and universal materials testing machine, respectively. The results indicate that the interfacial bonding strength firstly increases and then decreases with the increase of the intermetallic compounds (IMCs) thickness, which can reach to 90 MPa with the process of cold rolling 40% reduction → pre-heating at 400 °C for 20 min → hot rolling 60% reduction. Further, the growth of the interfacial IMCs of Cu9Al4, CuAl2 and CuAl is related to the pre-heating strategy and cold deformation. Thus, the kinetic equation is established. Moreover, the interfacial bonding mechanism is that the interfacial IMCs are fractured during the hot-rolling composite process and formed multiple ‘microscopic extrusion dies’ (MEDs) at the interface. Then, the fresh copper and aluminum are extruded from the MEDs (fractured IMCs) under the strong pressure by the hot rollers, and a solid welding interface between fresh copper and aluminum is achieved. Finally, the substrate metals and the intermetallic compound is formed into a serrated-like interface.

Study on IMC Growth Law of Solder Joints in Aerospace Electronic Products and Its Influence on Reliability

In order to better understand the influence degree of temperature curve parameters on the growth characteristics of intermetallic compounds (IMC) in solder joints during reflux welding, the influence of different temperature curve parameters on the thickness of IMC in Sn63Pb37 solder joints was explored based on the orthogonal test method. A multiple regression model was established for each parameter and the thickness of IMC. In addition, the results show that: (1) The influence degree of temperature curve parameters on IMC thickness in descending order is the highest temperature, liquidus time, cooling time and cooling rate. (2) The coefficient of the established multiple regression model is R2=0.70391. In this model, the IMC thickness increases with the increase of the maximum reflow temperature and liquidus time and decreases with the increase of the cooling time. (3) When the thickness of IMC is 1 μm- 4 μm, the thermal shock reliability of solder joints decreases with the increase of IMC thickness.

To suppress thermomigration of Cu–Sn intermetallic compounds in flip-chip solder joints

We report here an approach to inhibit Cu–Sn intermetallic compounds (IMCs) in flip chip solder joints under thermal-gradient annealing. We reflowed two types of solders joints, Cu/SnAg/Cu and Cu/SnAg/Ni, in an oven (isothermal) and on a hot plate (with thermal-gradient) at 260 °C. During the isothermal reflow, the IMC growth rates in the top and bottom sides of the solder joint were ∼4.0 × 10−2 and 8.9 × 10−2 μm/min, respectively. However, the IMC growth rate increased to 7.8 × 10−1, 7.9 × 10−1, and 8.9 × 10−1 μm/min in the cold ends with low, medium, and high thermal gradients, respectively. Yet, the IMC thickness on the hot ends remained almost unchanged. These results indicate that the thermal gradient has facilitated the Cu–Sn IMC formation in the cold ends. But, when a Ni film was sandwiched at the cold end, the IMC growth rates in the cold end were reduced to ∼9.7 × 10−2, 1.4 × 10−1, and 1.5 × 10−1 μm/min with low, medium, and high thermal gradients, respectively, indicating that the thermomigration of IMCs was retarded by the Ni. It is speculated that the Ni layer transformed the IMCs on the hot end into stable (Cu,Ni)6Sn5 ternary IMCs, and thus the thermomigration of Cu was suppressed. A kinetic model is also proposed to address the competitive reactions of Cu-molten solder joints.

Expectation–maximization machine learning model for micromechanical evaluation of thermally-cycled solder joints in a semiconductor

This paper aims to study the microstructural and micromechanical variations of solder joints in a semiconductor under the evolution of thermal-cycling loading. For this purpose, a model was developed on the basis of expectation–maximization machine learning (ML) and nanoindentation mapping. Using this model, it is possible to predict and interpret the microstructural features of solder joints through the micromechanical variations (i.e. elastic modulus) of interconnection. According to the results, the classification of Sn-based matrix, intermetallic compounds (IMCs) and the grain boundaries with specified elastic-modulus ranges was successfully performed through the ML model. However, it was detected some overestimations in regression process when the interfacial regions got thickened in the microstructure. The ML outcomes also revealed that the thermal-cycling evolution was accompanied with stiffening and growth of IMCs; while the spatial portion of Sn-based matrix decreased in the microstructure. It was also figured out that the stiffness gradient becomes intensified in the treated samples, which is consistent with this fact that the thermal cycling increases the mechanical mismatch between the matrix and the IMCs.

Characterization of Sn-xIn Solders and Thermomigration-Induced Interfacial IMC Growth of Cu/Sn-xIn/Cu Micro Solder Joints

The melting behavior and microstructure of bulk Sn-xIn (x = 6, 12 and 24, wt.%) solders and the thermomigration, elemental distribution and intermetallic compound (IMC) growth in Cu/Sn-xIn/Cu micro solder joints during soldering and aging under temperature gradient (TG) were investigated. The results indicate that In addition effectively decreased the melting temperature of the bulk solders. Only the InSn4 phase was detected when In addition was increased to 24 wt.%. During soldering under TG, the growth rate of the interfacial IMC layer at the cold end interfaces gradually decreased as the In content increased. The mechanism of microstructure evolution and elemental distribution in the micro solder joints was revealed based on the TG-induced atomic thermomigration (TM). The chemical potential gradient of atoms was enhanced by TM, and the rapid diffusion of atoms in the liquids resulted in a uniform distribution of In element in both solders and the IMC phase during soldering. While during aging under TG, there was a smaller chemical potential gradient due to the slow atomic diffusion rate. At this time, TG dominated the atomic migration, which resulted in a nonuniform distribution of the In element in the whole joints. This study provides further insight into the application of In-containing solders in electronic packaging.

Study on the Solder Joint Reliability of New Diamond Chip Resistors for Power Devices

New diamond chip resistors have been used in high-power devices widely due to excellent heat dissipation and high-frequency performance. However, systematic research about their solder joint reliability is rare. In this paper, a related study was conducted by combining methods between numerical analysis and laboratory reliability tests. In detail, the shape simulation and thermal cycling finite element simulation for solder joints with different volumes were carried out. The optimized solder volume was 0.05 mm3, and the maximum thermal cycling stress under the optimized shape was 38.9 MPa. In addition, the thermal cycling tests with current and high temperature storage tests were carried out for the optimized solder joint, which showed good agreement with the simulation results, clarified the growth and evolution law of intermetallic compound at the interconnection interface, and proved the optimized solder joint had great anti-electromigration, temperature cycling and high temperature storage reliability. In this work, an optimized solder joint structure of a diamond chip resistor with high reliability was finally obtained, as well as providing considerable reliability data for the new type of diamond chip resistors, which would boost the development of power devices.