Search Results (1,144)

To ensure the highest safety standards in modern automobiles, the industry is constantly adopting zero-defect frameworks, such as AEC-Q100, which aims for defective-parts-per-billion (DPPB) or grade-0 level reliability standards in automotive integrated-circuit (IC) packages. Most contemporary wire-bonded packages use either pure copper (Cu) or palladium (Pd)-coated copper (PCC) wires bonded to aluminum (Al) bond pads as interconnections. This choice is made due to their lower cost and superior electrical and mechanical performance, compared to traditional gold wire-based devices. However, these Cu–Al wire-bonded interconnections are prone to ion-induced lift-off/open-circuit corrosion failures when exposed to even trace amounts (<20 ppm) of extrinsic and/or intrinsic halide (Cl⁻ and Br⁻) contaminants, decreasing device longevity. This study investigates corrosion failure mechanisms in Cu and PCC wire-based devices by subjecting non-encapsulated devices to a highly accelerated aqueous-immersion screening test containing 100 ppm chloride (Cl⁻), 100 ppm bromide (Br⁻), and a mixed-ion solution (MX: Cl⁻ + Br⁻). The screening results indicate that even control PCC-Al devices with a Pd overlayer can be susceptible to Cl⁻ and Br⁻ induced corrosion, with 21 ± 1.6% lift-off failures in MX-solution. In contrast, applying a novel Cu-selective passivation reduced lift-off to 3.3 ± 0.6% and introducing phosphonic-acid-based inhibitor into the MX solution eliminated lift-off failures, demonstrating markedly improved reliability. Full article

Integration of renewable energy into modern power grids remains limited by intermittency and the need for reliable energy storage. Redox flow batteries (RFBs) are promising for large-scale energy storage, yet their widespread adoption is hindered by the high cost. In this study, we investigate isopropanol as a redox-active species with Pt-Cu alloy electrocatalysts for aqueous-organic RFBs. A series of Pt_xCu catalysts with varying Pt:Cu ratios were synthesized and studied for isopropanol electro-oxidation reaction (IPAOR) performance. Among them, PtCu demonstrated the best performance, achieving a low activation energy of 14.4 kJ/mol at 0.45 V vs. RHE and excellent stability at 1 M isopropanol (IPA) concentration. Kinetic analysis and in situ attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy revealed significantly reduced acetone accumulation on PtCu compared to pure Pt, indicating enhanced resistance to catalyst poisoning. Density functional theory (DFT) calculations further identified the first proton-coupled electron transfer (PCET) as the rate-determining step (RDS) with C-H bond scission as the preferred pathway on PtCu. A proof-of-concept PtCu-catalyzed H-cell demonstrated stable cycling over 200 cycles, validating the feasibility of IPA as a low-cost, regenerable redox couple. These findings highlight PtCu-catalyzed IPA/acetone(ACE) chemistry as a promising platform for next-generation aqueous-organic RFBs. Full article

Accumulative rolling bonding (ARB) Cu/Nb nanolaminates have been widely observed to exhibit unique and large numbers of interface-based plasticity mechanisms, and these have been associated with the many extraordinary properties of the material system, especially resistances in extreme engineering environments (mechanical/pressure, thermal, irradiation, etc.) and ability to self-heal defects (microstructural, as well as radiation-induced). Recently, anisotropy in the interface shearing mechanisms in the material system has been observed and much discussed. The Cu/Nb nanolaminates appear to shear on the interface planes to a much larger extent in the transverse direction (TD) than in the rolling direction (RD). Related to that, in this present study we observe interface rotation in Cu/Nb ARB nanolaminates under constrained and unconstrained loading conditions. Although the primary driving force for interface shearing was expected only in the RD, additional shearing in the TD was observed. This is significant as it represents an interface rotation, while there was no external rotational driving force. First, we observed interface rotation in in situ rectangular micropillar compression experiments, where the interface is simply sheared in one particular direction only, i.e., in the RD. This is rather unexpected as, in rectangular micropillar compression, there is no possibility of extra shearing or driving force in the perpendicular direction due to the loading conditions. This motivated us to subsequently perform in situ microbeam bending experiments (microbeam with a pre-made notch) to verify if similar interface rotation could also be observed in other loading modes. In the beam bending mode, the notch area was primarily under tensile stress in the direction of the beam longitudinal axis, with interfacial shear also in the same direction. Hence, we expect interface shearing only in that direction. We then found that interface rotation was also evident and repeatable under certain circumstances, such as under an offset loading. As this behaviour was consistently observed under two distinct loading modes, we propose that it is an intrinsic characteristic of Cu/Nb interfaces (or FCC/BCC interfaces with specific orientation relationships). This interface rotation represents another interface-based or interface-mediated plasticity mechanism at the nanoscale with important potential implications especially for design of metallic thin films with extreme stretchability and other emerging applications. Full article

We evaluated for the morphology and growth behavior of IMC grain according to number of reflows of solder cap pure Sn microbumps. In the structure of Ni barrier/Cu layer between Cu pillar and pure Sn, solder cap pure Sn on the top layer was analyzed for the behavior change of IMC grain according to the number of reflows. The height and diameter of the bumps on the wafer were designed to be 40 μm and 30 μm, respectively. The vertical structure of the microbump consisted of Ti/Cu (1000 Å/2000 Å), Cu pillar (20 µm), Ni barrier (3 µm), and Cu (1 µm). The overall height of the bump is about 40 μm. Additionally, the height of the solder cap pure Sn as the last layer is 20 μm. The diameter of the bump is 30 μm. It was formed using plating. After plating to solder cap Sn, it was finally formed for the microbump using reflow. Samples were prepared according to the number of reflows (1, 3, 5, 7, and 9). To observe the grain morphology of the IMC, the pure Sn on the upper layer (solder cap) was removed using SupraBond RO-22 etchant. In the removed state, the morphology of the IMC grain was evaluated to the inside surface of bump using SEM and a 3D scope. The average number of IMC grains decreased linearly during reflow cycles 1 to 5 and then gradually decreased during reflow cycles 7 to 10. The average surface area of IMC grains was 18.243 μm when reflow was performed once. The average surface area of IMC grains increased proportionally for reflow cycles 1 to 10. Based on the experimental results, when the count of reflow was performed more than 10 times, it was confirmed that the solder cap pure Sn was reduced by more than 50% due to the increase in the area of IMC grain. Full article

Understanding how solvents influence the luminescence behavior of Cu(I) complexes is crucial for designing advanced optical sensors. This study reports the synthesis, structures and photophysical investigation of an 8-hydroxyquinoline-functionalized 1H-imidazo[4,5-f][1,10]phenanthroline ligand, ipqH₂, and its four Cu(I) complexes with diphosphine co-ligands. Photoluminescence studies demonstrated distinct solvent-dependent excited-state mechanisms. In DMSO/alcohol mixtures, free ipqH₂ exhibited excited-state proton transfer (ESPT) and enol-keto tautomerization, producing dual emission at about 447 and 560 nm, while the complexes resisted ESPT due to hydrogen bond blocking by PF₆⁻ anions and Cu(I) coordination. In DMSO/H₂O, aggregation-caused quenching (ACQ) and high-energy O–H vibrational quenching dominated, but complexes 1 and 2 showed a significant red-shifted emission (569–574 nm) with high water content due to solvent-stabilized intra-ligand charge transfer and metal-to-ligand charge transfer ((IL+ML)CT) states. In DMSO/DMF, hydrogen bond competition and solvation-shell reorganization led to distinct responses: complexes 1 and 3, with flexible bis[(2-diphenylphosphino)phenyl]ether (POP) ligands, displayed peak splitting and (IL + ML)CT redshift emission (501 ⟶ 530 nm), whereas complexes 2 and 4, with rigid 9,9-dimethyl-4,5-bis(diphenylphosphino)-9H-xanthene (xantphos), showed weaker responses. The flexibility of the diphosphine ligand dictated DMF sensitivity, while the coordination, the hydrogen bonds between PF₆⁻ anions and ipqH₂, and water solubility governed the alcohol/water responses. This work elucidates the multifaceted solvent-responsive mechanisms in Cu(I) complexes, facilitating the design of solvent-discriminative luminescent sensors. Full article

In response to the actual needs of pure copper bonding wires, it is crucial to develop a chromium-free passivator that is environmentally friendly and has excellent corrosion resistance. In this study, three different composite organic formulations of chromium-free passivation solutions are selected: 2-Amino-5-mercapto-1,3,4 thiadiazole (AMT) + 1-phenyl-5-mercapto tetrazolium (PMTA), 2-mercaptobenzimidazole (MBI) + PMTA, and Hexadecanethiol (CHS) + sodium dodecyl sulfate (SDS). The performance analysis and corrosion mechanism were compared with traditional hexavalent chromium passivation through characterization techniques such as XRD, SEM, and XPS. The results show that the best corrosion resistance formula is the combination of the PMTA and MBI passivation agent, and all its performances are superior to those of hexavalent chromium. The samples treated with this passivation agent corrode within 18 s in the nitric acid drop test, which is better than the 16 s for Cr⁶⁺ passivation. The samples do not change color after being immersed in salt water for 48 h. Electrochemical tests and high-temperature oxidation test also indicate better corrosion resistance than Cr⁶⁺ passivation. Through the analysis of functional groups and bonding, the excellent passivation effect is demonstrated to be achieved by the synergistic action of the chemical adsorption film formation of PMTA and the anchoring effect of MBI. Eventually, a dense Cu-PMTA-BMI film is formed on the surface, which effectively blocks the erosion of the corrosive medium and significantly improves the corrosion resistance. Full article

Multi-material structures have great potential in high-end fields such as aerospace and energy. Which integrate the advantages of various metals and meet the demands of complex working conditions. Among additive manufacturing technologies for multi-material structures, wire-based processes have become a research hotspot due to their high material utilization, low cost, and high efficiency. This article systematically reviews the progress of research on this technology. The working principles and characteristics of common heat sources (WAAM, LWAM, EBAM) are introduced. Furthermore, the advantages and limitations of these heat sources for manufacturing multi-material structures are critically analyzed. Moreover, various metal wire combination systems (such as steel/Ni, Al/steel, Ti/Al, and Cu/Ti, etc.) were reviewed, and the differences and influences of different wire feeding methods and directions were discussed. The review highlights research findings on microstructure regulation, interfacial bonding mechanisms, and the mechanical property optimization of polymetallic structures. The influence laws of critical process parameters on structural properties are also elucidated. The existing problems in the current research were pointed out, and the future development trends were prospected. Unlike previous articles, this review establishes a more comprehensive process–structure–performance framework through the discussion of integrated heat source characteristics, wire feeding systems, and interface adjustment strategies. It aims to provide references for promoting the development and engineering application of additive manufacturing technology for wire-based multi-metal structures. Full article

A sheet-type sinter-bonding material was developed to form thermally stable and highly heat-conductive joints suitable for wide-bandgap (WBG) semiconductor dies and high-heat-flux devices, and its bonding characteristics were investigated. To enhance the cost-competitiveness of the bonding material, Ag-coated Cu (Cu@Ag) particles were employed as fillers instead of conventional Ag particles. To facilitate accelerated sintering, a bimodal particle size distribution comprising several micron- and submicron-sized particles was adopted by synthesizing and mixing both size ranges. For sheet fabrication, a decomposable resin was used as the essential binder component, which could be removed during the bonding process via thermal decomposition. This approach enabled the formation of a sintered bond line composed entirely of Cu@Ag particles. Thermogravimetric and differential thermal analyses revealed that the decomposition of the resin in the sheet occurred within the temperature range of 290–340 °C. Consequently, sinter-bonding conducted at 350 °C and 370 °C exhibited significantly superior bondability compared to bonding at 330 °C. In particular, sinter-bonding at 350 °C for just 60 s resulted in a highly densified joint microstructure with a low porosity of 7.6% and high shear strength exceeding 25 MPa. The formation of the bond line was initiated by sintering between the outer Ag shells of the adjacent particles. However, with increasing bonding time or temperature, sintering driven by Cu diffusion from the particle cores to the outer Ag shells, particularly in the submicron-sized particles, was progressively enhanced. These results obtained from the fabricated sheet-type materials demonstrate that, even with the use of resin, rapid solid-state sintering between filler particles combined with the removal of resin through decomposition enables the formation of a metallic bond line with excellent thermal conductivity. Full article

High-performance but expensive neodymium-iron-boron (Nd-Fe-B) magnets are widely used in automotive and electrical applications. Prospective candidates for rare-earth-free magnets include Fe-based magnets such as L1₀-FeNi and α″-Fe₁₆N₂ phase. However, these rare-earth-free magnets cannot replace Nd-Fe-B magnets due to their lower coercivity. Thus, the development of Sm-based magnets, using the relatively abundant rare-earth element Sm, has become a focus of attention. A promising, cheaper alternative with excellent magnetic properties is the Samarium-iron-nitride (Sm-Fe-N) magnet. This paper describes the production and magnetic properties of Sm-Fe-N powders with Th₂Zn₁₇ and TbCu₇ phases. The production process and magnetic properties of Sm-Fe-N bonded magnets prepared from the powders are also described. Current approaches for producing Sm-Fe-N sintered magnets are included. Full article

The relationship between the structure and function of bacterial laccases has garnered significant research attention thanks to their straightforward molecular structure. Nevertheless, studies examining the impact of an altered molecular structure on the heterologous expression of bacterial laccases in Escherichia coli remain scarce. Our research focuses on elucidating the impact of incorporating copper ions into the molecular structure of modified CotA on its exogenous expression in E. coli as well as its impact on the significance of the amino acid residues surrounding the internal electron channels and water molecule channels of the enzyme molecule. The results show that single-site mutation may affect the expression of CotA by affecting its soluble expression with different binding capacities for copper ions. In addition, the mutants exhibited different laccase activity levels. The catalytic efficiency of T466A was found to be significantly enhanced, reaching 2.29 times that of the wild type. We used structural models to illustrate the correlation between molecular structure and function after the replacement of three mutation sites with alanine. The reduction of hydrogen bonds may be an important factor influencing Cu²⁺’s binding ability and the water molecule production rate. The T466A mutant exhibited strong decolorization ability for Reactive Blue 19 and Eriochrome Black T with 42.2% and 58.2% decolorization rates after one hour of reaction, respectively. This study demonstrates that the molecular mutation studied influences the CotA expression level, enzyme activity, and dye decolorization. Full article

Self-assembled monolayers of alkane thiolate and alkane selenolate have been proven to inhibit atmospheric corrosion, but upon prolonged exposure to the important constituents of indoor atmosphere, namely humidified air with formic acid, the protective layer eventually breaks, but the exact reason is not yet clear. In this paper, we report on an XPS study of co-adsorbed formic acid and hexane selenol on a Cu surface. Adsorption of hexane selenol at room temperature breaks the Se-C bond, leaving a monolayer of Se on the surface, whereas adsorption at 140 K leaves a layer of selenolate. Formic acid exposure to the selenolate-Cu surface leads to adsorbed formate on unprotected areas and absorption of formic acid within the alkane chain network. During heating, the formic acid desorbs and the Se-C bond breaks, but formic acid does not accelerate the Se-C scission, which occurs just below room temperature both with and without formic acid. Thus, formic acid alone does not affect the Se-C bond, but its presence may create disorder and open up the alkane carpet for other species. Selenol removes formate and oxide from the surface at room temperature. The Se-C bond breaks and the alkane chain reacts with surface oxygen to form carbon oxides and volatile hydrocarbons. Full article

As 3D stacking technologies advance, low-temperature hybrid Cu bonding has become essential for fine-pitch integration. This study focuses on evaluating Pd nanolayers deposited by electroless plating (ELP) on Cu surfaces and compares them to electroplated (EP) Pd to assess their suitability for hybrid bonding. Pd nanolayers (5~7 nm) were deposited on Cu films, and their surface morphology, crystallinity, and chemical composition were characterized using AFM, TEM, GIXRD, and XPS. EP-Pd layers exhibited lower roughness and larger grain size, acting as effective Cu diffusion barriers. In contrast, ELP-Pd layers showed small grains, higher surface roughness, and partial Cu diffusion and oxidation. At 200 °C, both Pd layers enabled bonding, but ELP-Pd samples achieved more uniform and continuous interfaces with thinner copper oxide layers. Shear testing revealed that ELP-Pd samples exhibited higher average bonding strength (20.58 MPa) and lower variability compared to EP-Pd (16.47 MPa). The improved bonding performance of ELP-Pd is attributed to its grain-boundary-driven diffusion and uniform interface formation. These findings highlight the potential of electroless Pd as a passivation layer for low-temperature hybrid Cu bonding and underscore the importance of optimizing pre-bonding surface treatments for improved bonding quality. Full article

Growing demand for high-performance system semiconductors has highlighted the importance of hybrid bonding, where precise control of copper dishing is essential. This requirement reinforces the role of chemical mechanical planarization (CMP). Many studies have sought to control dishing by modifying slurry chemistry or adjusting mechanical parameters, but these approaches have not been sufficient. This study addresses the overlooked effect of process temperature and demonstrates its role in integrating both chemical and mechanical behaviors in CMP. Removal rates of Cu, Ta, and SiO₂ films were evaluated through blanket wafer experiments, and all exhibited Arrhenius-type behavior as a function of temperature and activation energy. The results showed that maintaining the process temperature at 30 °C balanced selectivity and minimized dishing on patterned wafers. To enable precise temperature control, a vortex-tube-based pad cooling system was developed. Without temperature control, dishing increased by 12 nm in the 100 µm pattern and 16 nm in the 50 µm pattern. With temperature control, dishing was reduced to 4 nm and below 1 nm, respectively. These results demonstrate that process temperature is a key parameter for controlling selectivity and ensuring precise dishing control, which is critical to meeting the requirements of hybrid bonding. Full article

Grape pomace (GP), a significant by-product of winemaking, is gaining increasing recognition for its potential as a source of bioactive compounds with antioxidant and cardioprotective properties. This study aimed to characterize the polyphenolic profile, fatty acid composition, and antioxidant activity of 17 GP samples from Transylvanian cultivars. Polyphenolic content was determined using the Folin–Ciocalteu method and high-performance liquid chromatography coupled with diode array detection and electrospray ionization mass spectrometry (HPLC–DAD–ESI MS) analysis. Fatty acid composition was analyzed using gas chromatography with flame ionization detection (GC–FID). Antioxidant capacity was assessed using five methods, which included the 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging, 2,2′-azino-bis (3-ethylbenzothialzoline-6-sulfonic acid) (ABTS) radical scavenging, ferric-reducing antioxidant power (FRAP), cupric ion reducing antioxidant capacity (CUPRAC), and reducing power (RP) assays. Additionally, all extracts were analyzed by Fourier transform infrared (FTIR) spectroscopy to identify the presence of functional groups and chemical bonds associated with bioactive compounds. The results showed that Neuburger (NE), Radames (RA), and Regent (RE) cultivars had the highest phenolic concentrations, particularly of catechin, epicatechin, and procyanidin dimers. NE and Feteascǎ Regalǎ (FR) exhibited the greatest radical scavenging and electron transfer activities across multiple antioxidant assays. Rose Blaj (RB) and Astra (AS) displayed the most favorable fatty acid profiles, with high unsaturated-to-saturated fatty acid (UFA/SFA) and hypocholesterolemic-to-hypercholesterolemic fatty acid (H/H) ratios, as well as low atherogenicity (AI) and thrombogenicity (TI) indices, suggesting cardioprotective potential. Additionally, RB and NE cultivars also demonstrated a strong chelation of Cu²⁺ and Fe²⁺ ions, enhancing their antioxidant efficacy by mitigating metal-catalyzed oxidative stress. These findings underscore the potential of GP, particularly from NE, RB, RA, and AS cultivars, the last three of which were homologated in Transylvania at SCDVV Blaj, as valuable sources of health-promoting compounds for use in food, nutraceuticals, and other health-related applications. Full article

The selective oxidation of methane to methanol under mild conditions remains a significant challenge due to its stable C-H bond and the propensity for overoxidation of products. Herein, we investigated the Fe- and Cu-modified ZSM-5 catalysts using H₂O₂ as an oxidant for the selective oxidation of methane. It was found that the Fe/Cu ratio had a great impact on methanol yield. The Fe₃Cu₁ displayed the highest methanol yield of 29.7 mmol g_cat⁻¹ h⁻¹ with a selectivity of 80.9% at 70 °C. Further analysis revealed that Fe₃Cu₁ showed the highest Fe³⁺ and Cu⁺ contents. The optimal dual valence cycle not only facilitates the efficient utilization of H₂O₂, promoting the activation of methane to •CH₃ at the Fe site, but also suppresses the deep oxidation caused by the Fenton-like effect of Fe/H₂O₂, thus maintaining the high yield and high selectivity of methanol. Full article