Abstract This study systematically evaluates the effects of seven surface finishes (bare Cu, HASL, OSP, ImSn, ImAg, ENIG, ENEPIG) on the interfacial microstructure, strain-rate-dependent shear properties, and high-temperature aging stability of SAC305 solder joints. Cross-sectional characterization, shear tests (0.1 mm/s and 1000 mm/s), and 150°C isothermal aging tests (0–1500 h) were conducted. Results show the interfacial IMC growth inhibition ability of surface finishes ranks as HASL > ImSn > ImAg > OSP > Bare Cu, with Ni/Au-based finishes (ENIG, ENEPIG) forming thinner (Cu, Ni) 6 Sn 5 layers. Mechanically, Cu and HASL exhibit excellent toughness across both strain rates, while ImAg and ENIG are prone to brittle fracture under high-speed loading. Under 150°C aging, ENEPIG and OSP maintain superior mechanical stability, whereas ImAg shows significant shear performance degradation due to rapid IMC growth and plastic decline. This work provides guidelines for surface finish selection in different electronic packaging scenarios.

So far, the application of accelerators in microvia filling via copper electrodeposition has been limited. In this study, ethylene trithiocarbonate (ET) was introduced as a novel accelerator into the copper plating bath for the first time. Chronopotentiometry results revealed that ET significantly enhanced the copper deposition rate, irrespective of the presence of Cl- . However, the accelerating effect of ET was concentration-dependent: It promoted copper deposition at lower concentrations but exhibited an inhibitory effect at higher concentrations. Notably, the critical concentration of ET decreased significantly in the presence of Cl-, which can be attributed to their competitive adsorption on the cathode surface. The accelerating mechanism of ET was further elucidated through cyclic voltammetry (CV) and rotating ring-disk electrode (RRDE) experiments. These studies demonstrated that ET enhances the rate-determining step (RDS) of copper deposition, with the effect being further amplified in the presence of Cl- . Pre-adsorption and desorption experiments confirmed that ET adsorbed onto the copper surface, thereby accelerating the deposition process. Additionally, a synergistic effect between ET and Clwas observed, beyond their competitive adsorption behavior. Microvia filling experiments demonstrated that with ET as the accelerator, efficient superfilling of microvias was achieved within 60 min in the plating bath containing PEG and Cl-, and this filling process was mainly governed by the curvature enhanced adsorbate coverage (CEAC) mechanism. ET'S Cl--independent acceleration and absence of sulfonate groups provide a structurally distinct alternative to conventional additives, offering new insights for designing high-efficiency accelerators in advanced PCB manufacturing

Based on calculation of phase diagrams (CALPHAD)-assisted phase fraction calculations, Sn-1Ag-0.7Cu-5Bi-xIn (x = 4, 8, 15, 17 wt

Single-phase Si modified beta-NiAl coatings with Si contents of 1.5 at.%, 2.0 at.%, and 2.7 at.% were prepared using Al-Si plasma irradiation, which are distinctively different from that of the conventional AlSi slurry-diffusion process that normally generates silicides precipitation. Their corrosion behavior under Na2SO4 +NaCl salt mixture deposits at 700 and 900 degrees C were investigated. Increasing the Si concentration from 1.5 at.% to 2.7 at.% improved the hot corrosion resistance of the beta-NiAl coatings significantly. forms alpha-SiO2 nano-particles within the oxide scale and promotes alpha-Al2O3 formation at the initially, and thus inhibits basic fluxing. HRTEM analysis showed that S was captured in some SiO2 particles, so its inward migration was slow down. Inside the coating, Mo is pinned by Si-rich particles in the interdiffusion zone, preventing acidic fluxing.

Sn-Bi-based solders used in photovoltaic interconnections are prone to severe oxidation during high-temperature processing, which degrades surface quality and solderability. In this work, Sn-Bi-In alloys containing 1-8 wt.

Using CALPHAD-assisted phase fraction calculations, Sn-1Ag-0.7Cu-5Bi-xIn (x = 4, 8, 15, 17 wt.

Abstract The mechanical reliability of microelectronic solder joints is predominantly governed by interfacial intermetallic compounds (IMCs), especially under long-term thermal exposure. Trace doping is an effective strategy for optimizing IMC properties, but the atomic-scale mechanisms underlying different dopants remain unclear. In this study, SAC305/Cu solder joints doped with Ni or Sb were fabricated, thermally aged at 170°C for 750 h, and Mechanical Property Testing combined with first-principles calculations. Results reveal distinct doping mechanisms: Ni substitutes Cu in Cu 6 Sn 5 , introducing 3d orbital hybridization near the Fermi level to strengthen atomic bonding, reduce formation energy, and significantly enhance mechanical performance. Sb replaces Sn, stabilizing the lattice via hybridization of the low-energy 4 s orbitals, leading to moderate initial property improvements but performance saturation and degradation at higher concentrations due to competing orbital interactions. Ni doping also maintains superior plasticity retention compared to Sb doping. These findings clarify dopant-specific tuning mechanisms, providing theoretical guidance for the design of high-reliability solder joints in advanced electronics.

This research analyzed the microstructure evolution, defect formation, and mechanical performance degradation mechanism of the bonding wire and Au-/Al interface with long-term exposure to 85 degrees C/85 %RH thermal-humidity bias (THB). The results showed that intermetallic compound (IMC) mainly appeared at the Au-/Al interface, initially composed of AuAl and Au2Al, and transformed into Au4Al after THB, with a small amount of Au8Al3 phase present. The formation of IMC was attributed to the mutual diffusion of Au and Al. The wet heat environment accelerated the formation of IMC. The average thickness of IMC increased the fastest after 200 h THB. With the extension of the aging time, the growth rate of IMC gradually decreased, following the power function law. After THB, irregular particles containing Ag appeared on the surface of the Au wire, and the particles gradually moved from the second joint to the first joint as the aging continued. The mechanical performance results indicated that excessive IMCs, cracks, and voids at the interface deteriorated the mechanical properties of the Au wire bonds. The average maximum tensile force decreased by 62.42 %, and the average fracture energy also decreased by 49.35 %. The failure mode changed from wire fracture to bond ball detachment. This research explored the evolution of IMCs, element diffusion, and failure mechanism of bonding joints in the long-term wet heat environment, established the IMC growth rate equation and Au wire bonding electrochemical corrosion model, which is helpful for promoting further understanding in the field of metal wire bonding materials research and application.

The effects of elements In, Bi and Sb with1, 2, 3, 4 and 5 wt.% added to pure Sn metal were investigated, in order to study their influence on their melting behavior, microstructure and mechanical properties. The findings indicate that the addition of In, Bi and Sb reduces the undercooling of pure Sn. After adding the three elements to the Sn/Cu solder joints, the microstructure remains predominantly composed of the β-Sn phase and the Cu6Sn5 phase, aligning with the microstructures of the corresponding Sn based bulk alloys. The difference arises when Bi is added up to 5 wt.%, leading to the precipitation of Bi particles. The element In, however, only dissolves in the β-Sn and Cu6Sn5 phases. When the mass fraction of Sb reaches 5%, a dark gray square SbSn phase precipitates. Among the elements, Bi and In play the role of solid solution strengthening, due to the precipitation phase of Bi and the presence of SbSn phase. Additionally, Bi and Sb exhibit precipitation strengthening effect. These strengthening effects make the maximum shear force and microhardness of the joints with the increase in the amount of alloying elements added to show a monotonous upward trend. The results show that the strengthening effect of Bi is superior to that of Sb,In when the doping amount of alloying elements is the same. The research results have guiding significance for alloy design, especially in the field where the reliability of electronic equipment is required at high temperature.

This paper delves into the impact of the Bi volume fraction in SnxBi-SAC joints through the creation of a SnBiSAC305 hybrid solder joint, connecting the copper pad to the resistor with nickel electrode. The study reveals that the SnBi volume fraction in the SnBi-SAC hybrid solder joint significantly influences joint formation, reflow temperature, and solid-liquid diffusion at the fusion interface. These factors collectively impact the mechanical properties of the hybrid solder joints in various ways. Under the experimental conditions, it is concluded that the optimal mechanical properties of the solder joints are achieved when the Bi content is 40 %. Additionally, Finite Element simulation is employed to identify the region of maximum stress at the junction between SAC305 and the nickel electrode resistance.

Although carbon aerogel/carbon fiber composites (CACFs) exhibit excellent thermal stability and high-temperature insulating capacity, their compressive strength remains limited because of interfacial defects arising from mismatched carbonization-induced shrinkage between fibers and matrix. Herein, we developed robust CACFs (RCACFs) with ultralow interfacial defects using an in situ repair route to simultaneously meet the demands of high-temperature insulation and structural integrity. X-ray micro computed tomography (micro-CT) revealed that the repair process reduced the interfacial defects (>9.73 μm3) from 22.4 to 4.6%. The repaired composite (0.75 g·cm-3) achieved a compressive strength of 14.3 MPa at a 5% strain, a 180.4% improvement over that of untreated CACFs (5.1 MPa, 0.73 g·cm-3). During high-temperature tensile testing at 1200 °C, in situ micro-CT confirmed the excellent thermal mechanical stability of RCACFs, which retained stable small voids (<0.5 × 102 mm3) and effectively suppressed defect expansion during loading. The as-prepared RCACFs maintained a low thermal conductivity of 0.173 W·m-1·K-1 at 25 °C and 0.901 W·m-1·K-1 at 1200 °C, exhibited negligible volumetric shrinkage at 1600 °C, and demonstrated superior ablation resistance with a linear ablation rate of 1.3 μm·s-1 under an oxyacetylene flame at 1800 °C. These results position RCACFs as promising materials for high-temperature insulation and load-bearing applications in extreme environments.

This study systematically investigates the effects of indium (In) addition (4-17 wt%) on Sn0.5Ag0.7Cu5Bi solder joints through thermal analysis, microstructural characterization, and mechanical testing. Key findings reveal that 12 wt% In emerges as the optimal composition, offering superior mechanical performance with 87% ductile fracture and significantly suppressed intermetallic compound (IMC) growth. However, high-In alloys (15-17 wt%) exhibit abnormal IMC thickening due to thermal activation near the aging temperature. Microstructural analysis suggests that In substitution at Sn sites causes the lattice to induce the aging local lattice contraction in eta '-Cu6Sn5, generating internal stresses that lead to cracking in low-In alloys after prolonged aging. Shear strength shows a nonmonotonic dependence on In content, decreasing as In increases, attributed to InSn4 phase formation. This research identifies 12 wt% In as the optimal composition for Sn0.5Ag0.7Cu5Bi-xIn solders, providing specific design rules for industrial applications: 1) enhanced drop resistance in mobile devices due to 87% ductile fracture; 2) cost reduction in automotive electronics by suppressing IMC growth (81% thickness reduction vs. 4In alloy); and 3) compatibility with flexible substrates via In-induced lattice contraction, validated by density functional theory calculations. These guidelines enable reliable solder joints in high-density IC packaging under thermal cycling.

The high input and output (I/O) data exchange, coupled with continuous increase in power density, elevates the risk of bonding interface performance degradation and electromigration (EM) failure during electrical transmission. This leads to polarity differences in interconnection structure, underscoring the urgent need to clarify the evolution of microscale bonding interfaces. This study investigates polarity effect in the chip-side Ag/Al system, revealing the evolution process of bonding interface under high current density. An EM theoretical model is established to analyze current-induced polarity effect on material migration and the growth evolution of intermetallic compounds (IMC) at the interface. Specifically, the cathode IMC layer thickness increased from 2.6 mu m to 7.5 mu m with an increase rate of 188.46%. And the anode has a higher rate of 3.8% than the cathode. Characterization has determined that IMC at bonding interface is predominantly the Ag2Al phase. The bonding wire surfaces in the middle and near the Al pad experience a combination of compressive stress and thermal migration, leading to the formation of white particles. Additionally, due to the bias voltage effect, white silver dendrites grow toward the anode joint on the chip's anode side under the influence of electrochemical migration (ECM). Tensile tests indicate that mechanical properties of the interface deteriorate after EM, and fracture mode transitions from neck fracture before EM to current forms of neck fracture and joint detachment. This study supplements and enhances the research framework of Ag/Al interface IMC at bonding joints, contributing to further development of reliable electronic packaging devices.

The electrochemical process of Cu–Mo composite coating prepared by citric acid system was studied by electrochemical workstation, SEM, EDS and XRD. The morphology and structure of Cu–Mo composite films under different current densities (0.01, 0.015, 0.02, 0.025, 0.03 A/cm2) were analyzed. It is found that citric acid can increase the deposition potential of copper and make the deposition potential of copper and molybdenum close to each other, thus contributing to copper-induced molybdenum co-deposition. With the increase of current density, the number of particles on the surface of the deposited Cu–Mo film increases, from nanometer level to tens of microns, from dense to fluffy. And the content of Cu in the film also increases with increasing current density, while the content of Mo decreases. The characteristic peak of Cu–Mo film in X-ray spectrum shifted to the right relative to that of Cu, and a new peak appears at 44.48°, suggesting the possible formation of a new phase in the material system. In addition, by conducting electrochemical migration tests on copper substrates with and without Cu–Mo composite plating, it was found that Cu–Mo composite plating has a better inhibition effect on the electrochemical migration behavior, and it can improve the corrosion resistance of copper substrate materials.

xNi (x = 0.005, 0.01, 0.03, 0.05, and 0.07 wt.

Continuously improving chip integration and increasing packaging density increase the risk of performance degradation and electromigration (EM) failure on the bonding interface during electrical transmission. While EM failure, as a time-accumulated failure, is one core challenge of semiconductor reliability and is particularly severe in highly integrated chips. However, the polarity differences existing in commercial devices and the evolving polarity characteristics of microscale bonding interfaces have not been well addressed. Therefore, this study describes the polarity effects of EM in a commercial chip-end Au-Al system and reveals the evolution of intermetallic compound (IMC) growth at bonding interfaces under high-density currents. An EM simulation model is developed to jointly analyze the influence of current-induced polarity effects on the evolution of material migration and IMC growth together with experimental results. Specifically, under the influence of the polarity effect, the thickness of the anode IMC layer is approximately twice as thick as that of the cathode. The IMC thickness on both sides is much thicker than the center under the influence of the size effect. Unlike previous studies, the IMC at the commercial bonding interface is mainly the Al3Au8 phase in columnar crystal morphology and the α-AlAu4 phase in nanocrystalline morphology, with the former being mainly located in the middle region of the IMC layer, while the latter is mainly located in the edge region of the IMC layer. Due to the overgrowth of the IMC layer, the tensile mechanical properties of the interface are degraded, and the failure mode transforms from a single neck fracture to a predominant joint detachment. This study complements and improves the research framework of Au/Al interface IMC at commercial chip joints and lays a theoretical foundation for the development of semiconductor chips toward high integration, high density, and high reliability.

A series of heterocyclic compounds containing diverse functional groups were investigated as target additives for copper electrodeposition in microvia filling applications. Theoretical calculations and electrochemical analyses were conducted to elucidate the correlation between functional group characteristics and their adsorption behaviours on copper surfaces. The results revealed that sulphur atoms (-S-), thiocarbonyl groups (-C = S), and benzene ring significantly enhanced the adsorption strength of additives. Fukui function calculations further identified sulphur atoms in heterocyclic structures as the most active adsorption sites. Linear sweep voltammetry (LSV) revealed that all target additives enhanced the electrochemical behaviour of copper deposition in the presence of Cl-. Notably, electrochemical impedance spectroscopy (EIS) indicated that thiocarbonyl (-C = S) groups amplified the accelerating effect, whereas benzene rings attenuated it. Hydrogen evolution experiments were employed to probe additive adsorption behaviour in Cu-2+-free solutions, confirming their intrinsic interaction with the substrate. Finally, microvia filling experiments established a critical relationship between adsorption strength and filling performance: only additives with moderate adsorption strength enabled defect-free superfilling, highlighting the importance of balanced interfacial interactions for optimal copper deposition.

Sn-3.0Ag-0.7Cu/Cu solder joint with Co doping amounts of 0, 0.005, 0.01, 0.03, 0.05 and 0.07 wt% were prepared, respectively, and then aged at 170 degrees C for 0, 250, 500 and 750 h. The low-speed shear test results show that the optimal addition of Co is 0.05 wt%. The doping of Co makes the network eutectic microstructures in the solder joint become chain-shaped and refined. During the aging process, the doping of each element inhibited the growth of Cu6Sn5 and Cu3Sn layers to varying degrees, but with the aging time prolonged, the inhibition effect of Co on Cu6Sn5 layer changed to promote the growth. The results of the high-speed shear test indicate that Codoping can marginally enhance the shear strength of solder joints prior to aging, but significantly deteriorate their high-speed shear performance after aging. The nanoindentation test results indicate that the addition of Co enhances the average modulus and average hardness of the Cu6Sn phase. Following Co doping, the material exhibits reduced plasticity, decreased dynamic load resistance, and a lower E/H ratio.

Hydrogen peroxide (H2 O2 ) is extensively used in medical disinfection, water treatment, and environmental protection. To achieve the green synthesis of H2 O2 , g-C3 N4 -based photocatalysis is an effective strategy and shows great potential. Nonetheless, single g-C3 N4 exhibits poor photocatalytic properties due to severe photogenerated charge recombination. To solve this challenge, this work enables F- adsorption on the surface of g-C3 N4 nanotubes in solution driven by Coulomb forces through pH adjustment and the addition of NH4 F. The photocatalytic H2 O2 production rate of the optimal F--decorated g-C3 N4 is three times higher than that of pure g-C3 N4 , attributing to the synergistic effect of F-and H+ . Quenching experiments verify that the photocatalytic H2 O2 production process of CNF is a two-electron oxygen reduction process. Electron quenching dynamics of g-C3 N4 and CNF are revealed by femtosecond transient absorption spectroscopy (fs-TAS). Compared to pure g-C3 N4 , CNF has an additional ultrashort lifetime (3.1 ps) representing the interfacial electron transfer from the conduction band of g-C3 N4 to F-. In situ fs-TAS results show that the interfacial electron transfer rate and electron utilization efficiency are respectively increased from 1.5 x 108 s-1 and 19 % in air to 5.0 x 108 s-1 and 45 % in O2 atmosphere with ethanol sacrificial agent. Hence, the O2 , H+ , and photogenerated electrons are key substances in the H2 O2 evolution. This work has elucidated the dynamics mechanism of enhanced photocatalytic performance of F--modified g-C3 N4 and provides inspiration for the design and synthesis of efficient g-C3 N4 -based photocatalysts. (c) 2025 Published by Elsevier Ltd on behalf of The editorial office of Journal of Materials Science & Technology.

In this study, the Calculation of Phase Diagrams (CALPHAD) method was employed to predict the phase constitution of Sn1Ag.7Cu3BixIn1.5Sb solder joints with different contents, which also guided the composition ratio of In in the system. Therefore, Sn1Ag.7Cu3BixIn1.5Sb (x = 4, 7, 12, 14, 17) solder joints were fabricated and investigated. According to experimental results, In addition could effectively lower the solidus and liquidus temperature supercooling degree of the alloy while increasing its melting range. In could substitute Sn atoms in the Cu6Sn5 phase to form a Cu6(Sn, In)5 phase, and could induce the formation of Ag2(Sn, In), Ag9In4. When the In content exceeds 12 wt.%, the matrix phase γ-InSn4 phase was formed. Based on the mechanical properties and post-mortem characterization, doping In could significantly ductile the solder joint with limited strength sacrifice, thanks to the increase in the phase volume fraction of the γ-InSn4 phase. This study provides a viable method to relieve the brittleness of Sn1Ag.7Cu3Bi1.5Sb solder alloy while achieving a lower soldering temperature, which could serve as a guideline for future solder alloy design.