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Laser impact welding: Investigation on microstructure and mechanical properties of molybdenum-copper welding joint
摘要： Due to their excellent properties, molybdenum and copper are widely used in the electronics industry. However, the welding of molybdenum and copper is difficult, which limits their application prospects in the field of microelectronics devices. This paper describes a novel method for Mo/Cu welding in micro devices: laser impact welding (LIW). The experimental results found that welding improved with the increase of laser energy. The springback and interface wave in the welding area were observed by optical microscope and scanning electron microscope (SEM) and the results showed that the shapes of the interface wave were flat and zigzag. Energy dispersive spectroscopy (EDS) showed little or no diffusion of elements at the welding interface. Tensile shear test results of the welded specimens showed that there were two kinds of failure forms: solder joint failure and solder joint edge failure. The nano-hardness of the materials in the welding area increased compared with the raw materials.
关键词： Laser impact welding,Springback,Interface wave,Molybdenum,Mechanical properties,Copper
更新于2025-09-23 15:23:52
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[IEEE 2018 19th International Conference on Electronic Packaging Technology (ICEPT) - Shanghai (2018.8.8-2018.8.11)] 2018 19th International Conference on Electronic Packaging Technology (ICEPT) - Study of the fabrication and organization properties of copper-based Ba<inf>1?x</inf>Sr<inf>x</inf>TiO<inf>3</inf> composites
摘要： Barium strontium titanate ceramic particles which have negative thermal expansion properties when it reaches reinforcement and copper which have high thermal conductivity are choosen as matrix of composites. Different content of strontium in barium strontium titanate ceramic particles reinforced copper matrix composites are prepared by Spark Plasma Sintering for electronic packaging applications. The methods of microstructure analysis are employed to observe the morphology of reinforcement and matrix in composites, and interfacial characteristics. Thermal expansion instrument and thermal conductivity equipment are used to test and analyze the thermal expansion and thermal conductive ability of the composites. And the conductivity of the composites is tested by intelligent resistance tester.
关键词： Thermal expansion ability,Barium strontium titanate,Copper matrix composites
更新于2025-09-23 15:22:29
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[IEEE 2018 28th International Symposium on Discharges and Electrical Insulation in Vacuum (ISDEIV) - Greifswald (2018.9.23-2018.9.28)] 2018 28th International Symposium on Discharges and Electrical Insulation in Vacuum (ISDEIV) - Two Dimensional Distribution of Metallic (Cu) Vapor in a Forced Vacuum Arc Extinction by LIF
摘要： It is important to observe the metallic vapor dissipation after interrupting a vacuum arc, for getting a deeper understanding of dielectric recovery processes, especially for DC interruptions. The object of this paper is to obtain two dimensional density distribution of copper vapor in a forced vacuum arc extinction. The method of laser-induced fluorescence (LIF) using a pulse laser with a central wavelength at 324.8 nm was adopted here. Meanwhile, an ICCD was used to capture the 510.6 nm fluorescence signal with an exposure time of 50 ns. The fluorescence can be distinguished from 125 μs (the moment of arc extinction) to 375 μs with a time interval of 25 μs. As a result, we could obtain the relative density distribution of ground-state copper metal vapor after the arc extinction. The results show that on the condition of CuCr25 contacts the metal vapor was evenly distributed in the gap and rapidly spread over time. The density of the copper vapor between the contacts dropped to less than 10% of the initial stage 200 μs after arc extinction. On the contrary, on the condition of CuCr50, higher copper metal vapor density at the moment of arc extinction was observed. It seems that the higher Cr content in the Cu-Cr contacts will lead to producing more metal vapor around current zero.
关键词： laser-induced fluorescence,copper metal vapor,vacuum arc
更新于2025-09-23 15:22:29
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Anterior segment optical coherence tomography (AS-OCT) as a new method of detecting copper deposits forming the Kayser-Fleischer ring in patients with Wilson disease
摘要： Purpose: Kayser–Fleischer ring pathognomonic for Wilson disease (WD) is formed of corneal copper deposits present predominantly within the anterior chamber angle at the Schwalbe’s line. The slit-lamp assessment commonly used as a standard of care cannot detect them early enough, as the angle view is obscured by the corneal limbus. The aim of the research was to evaluate the anterior segment optical coherence tomography (AS-OCT), as objective diagnostic assessment of copper deposits forming KF ring in patients with WD. Methods: Twenty-nine subjects (17 women) and twenty-nine controls (14 women) were enrolled and underwent slit lamp and AS-OCT assessment. Results: Kayser–Fleischer ring was not detected – either with a slit lamp or with AS-OCT – in any of the controls. Fifteen subjects presenting without KF ring at a slit-lamp examination were found to have a KF ring when examined with AS-OCT (p < 0.001), which confirms improved accuracy of AS-OCT, as compared to the slit-lamp examination. Conclusion: Our results support AS-OCT as a diagnostic procedure to offer better objectivity and accuracy as compared to a slit-lamp examination, both at the diagnostic stage and when monitoring changes in KF ring during medical therapy to assess its efficacy and patient compliance.
关键词： anterior segment optical coherence tomography,Kayser–Fleischer ring,Wilson disease,copper deposit
更新于2025-09-23 15:22:29
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Spectroscopic Studies of Magnetron Sputtering Plasma Discharge in Cu/O2/Ar Mixture for Copper Oxide Thin Film Fabrication
摘要： Magnetron sputtering plasma for the deposition of copper oxide thin film has been investigated using optical emission spectroscopy and Langmuir probe. The intensity of the light emission from atoms and radicals in the plasma were measured using optical emission spectroscopy (OES). Then, Langmuir probe was employed to estimate the plasma density, electron temperature and ion flux. In present studies, reactive copper sputtering plasmas were produced at different oxygen flow rate of 0, 4, 8 and 16 sccm. The size of copper target was 3 inches. The dissipation rf power, Ar flow rate and working pressure were fixed at 400 W, 50 sccm and 22.5 mTorr, respectively. Since the substrate bias plays an important role to the thin film formation, the substrate bias voltages of 0, -40, -60 and -100 V were studied. Based on OES results, oxygen emission increased drastically when the oxygen flow rate above 8 sccm. On the other hand, copper and argon emission decreased gradually. In addition, Langmuir probe results showed a different ion flux when substrate bias voltage was applied. Based on these plasma diagnostic results, it has been concluded that the optimized parameter to produce copper oxide thin film are between -40 to -60 V of substrate bias voltage and between 8 to 12 sccm of oxygen flow rate.
关键词： optical emission spectroscopy,Langmuir probe,thin film,magnetron sputtering,Copper oxide
更新于2025-09-23 15:22:29
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Copper electrodeposition on silicon electrodes
摘要： A two-step process is reported for the electrochemical deposition of copper layers on n-type silicon substrates using an acidic copper sulphate solution without addition of additives and no light assistance. Metal layers were generated on electrodes with different crystal orientations. The process consists of a combination of two very common techniques: chronoamperometry and pulse plating. The former technique is applied to obtain an instantaneous nucleation on the working electrode. Therefore, a large amount of metal nuclei is formed on the substrate before the pulse technique starts. The latter is, then, used to grow the particles previously generated and form a homogeneous metal layer with full coverage onto the semiconductor electrodes. The potential magnitudes are carefully chosen in line with energy levels observed at the semiconductor-electrolyte interface and were also calculated in this work.
关键词： silicon coating,seedless electroplating,copper plating,semiconductor-electrolyte interface,pulse plating
更新于2025-09-23 15:22:29
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Effects of selenisation temperature on photoluminescence and photoluminescence excitation spectra of ZnO/CdS/Cu2ZnSnSe4/Mo/glass
摘要： The effect of solar cell processing (including etching in KCN along with deposition of CdS and ZnO) on photoluminescence (PL) spectra and bandgap Eg (measured at 4.2 K by photoluminescence excitation) of Cu2ZnSnSe4 films, produced by selenising metallic precursors at 450°C, 500°C and 550°C, was studied. Temperature and excitation intensity analysis of the P1 dominant band in the PL spectra of solar cells suggests that after processing this band still can be assigned to the free-to-bound recombination of free electrons with holes bound at deep acceptor levels influenced by valence band-tails. However processing increased the intensity of P1 and blue shifted it. The strongest effect was observed for the film selenised at 500°C. For the film selenised at 450°C the blue shift and increase in the intensity were smaller and only a slight intensity rise was found for the film selenised at 550°C. The intensity increase we assign to a reduction in the concentration of non-radiative recombination centers on the surface because of the etching and changes in doping due to inter-diffusion of Cd, S, Se and Zn after the deposition of CdS. Such an inter-diffusion depends on the elemental composition of the films defining the chemistry of defects and influencing Eg which increased in the film selenised at 500°C but decreased in the other films. Processing increased the P1 shift rate (j-shift) with excitation power change in all the films demonstrating a higher compensation degree in the solar cells which is consistent with the formation of an interface layer containing new donors CdCu.
关键词： Optical spectroscopy,Copper zinc tin selenide,Photoluminescence,Solar cells,Selenisation
更新于2025-09-23 15:22:29
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Network Structured CuWO4/BiVO4/Co-Pi Nanocomposite for Solar Water Splitting
摘要： A network structured CuWO4/BiVO4 nanocomposite with a high specific surface area was prepared from CuWO4 nanoflake (NF) arrays via a method that combined drop-casting and thermal annealing. The obtained CuWO4/BiVO4 exhibited high catalytic activity toward photoelectrochemical (PEC) water oxidation. When cobalt phosphate (Co-Pi) was coupled with CuWO4/BiVO4, the activity of the resulting CuWO4/BiVO4/Co-Pi composite for the oxygen evolution reaction (OER) was further improved. The photocurrent density (Jph) for OER on CuWO4/BiVO4/Co-Pi is among the highest reported on a CuWO4-based photoanode in a neutral solution. The high activity for the PEC OER was attributed to the high specific surface area of the composite, the formation of a CuWO4/BiVO4 heterojunction that accelerated electron–hole separation, and the coupling of the Co-Pi co-catalyst with CuWO4/BiVO4, which improved the charge transfer rate across composite/solution interface.
关键词： copper tungstate,cobalt phosphate,oxygen evolution reaction,bismuth vanadate,photoelectrochemical water splitting
更新于2025-09-23 15:22:29
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Structural and thermoelectric properties of copper sulphide powders
摘要： Over the past few years, Cu-based materials have been intensively studied focusing on their structural and thermoelectric properties. In this work, copper sulphide powders were synthesized by the sol-gel method. The chemical composition and the morphological properties of the obtained samples were analyzed by X-ray diffraction, differential thermal analysis, and scanning electron microscopy. It is shown that the decomposition from one phase to another can be obtained by annealing. The electrical resistivity and the crystallite size were found to be strongly affected by the phase transition. Thermoelectric analyses showed that the digenite phase exhibits the highest power factor at room temperature. The Seebeck coefficient of the compound Cu1.8S shows a pronounced peak at the γ–β transition temperature. This behavior was statistically explained in terms of a dramatic increase in the disorder in the atoms-carriers ensemble.
关键词： thermoelectricity,copper sulphide,annealing temperature,phase transition
更新于2025-09-23 15:22:29
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Facile Sol-gel Synthesis of Metaloxide Nanoparticles in a Cellulose Paper Template
摘要： Ensembles of free standing particles of titanium, zinc, copper and iron oxides of 6-109 nm in size were sol-gel synthesized with a use of a cellulose paper as a template. The calcination time as short as 60 min at 550°C in air was found to be sufficient for the formation of crystalline single phase TiO2 or ZnO nanoparticles, Cu2O+CuO or Fe2O3+Fe3O4 nanocomposites and to burn out the organic components. The impurities initially present in the cellulose (Сa, Na, Cl) were detected in the synthesized compounds.
关键词： Sol-gel synthesis,Zinc oxide,Nanoparticle,Copper oxides,Cellulose,Iron oxides,Titanium oxide
更新于2025-09-23 15:22:29