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New approaches on laser micro welding of copper by using a laser beam source with a wavelength of 450 nm
摘要： Laser micro welding is specified with welding geometries below 1 mm and is used with increasing demand for contacting electronic components such as battery and fuel cells. Fiber lasers with a wavelength in the near infrared range (IR, λ ≈ 1 μm) have established themselves for this purpose. The laser welding process allows processing of parts in the micron range but reduces the surface quality of the processed parts at the same time. Furthermore, weld defects can occur due to process instabilities caused by the low absorptivity (<5%) of copper for infrared radiation. Therefore, alternative laser beam sources and processes have to be established, to avoid these negative effects on the weld seam quality. Laser beam sources in the visible wavelength range (VIS) prove to be an alternative due to an increased absorption of the laser energy in copper-based alloys. This paper presents the observation of laser micro welding of Cu-ETP and CuSn6 specimen with a thickness between 150 μm and 1 mm. The diode laser is specified by a wavelength of 450 nm and a nominal output power of 150 W. The surface roughness of the weld seam and the overall weld seam geometry for heat conduction welding are investigated. The laser energy absorption is measured using two integrating spheres to compare the results quantitatively to measurements conducted with laser sources of 1070 nm and 515 nm. For detailed observation high speed imaging is used to observe the melt pool dynamics. Simulations are conducted, to optimize the dimensioning of optics and laser beam source. Finally, the possible use of the novel laser beam source for various technical joining applications is discussed and evaluated and the influence of the use of protective gas is observed.
关键词： heat conduction welding,scanner system,laser micro welding,copper,modelling,450 nm
更新于2025-09-23 15:21:01
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Performance evaluation and optimization of the cooling system of a hybrid thermionic-photovoltaic converter
摘要： Hybrid thermionic-photovoltaic (TIPV) converters are efficient and clean solutions for the direct conversion of thermal energy to electricity, taking advantage of both the photovoltaic and thermionic phenomena. An important hurdle for their efficient operation is the overheating of the PV cell integrated within the TIPV anode, due to partial conversion of the emitted electron and photon fluxes to thermal heat. This obstacle needs to be overcome with an efficient, yet practical, cooler. In this work, a copper plate heat spreader is experimentally tested for TIPV cathode temperatures up to 1450 °C, whilst its performance is also assessed using a validated CFD model for temperatures up to ~2000 °C. A multi-parametric analysis is conducted testing two coolants: i) a water/ethylene glycol mixture at various temperatures (?5–40 °C) and mass flow rates (0.05–0.4 kg·s?1), and, ii) cryogenic liquid nitrogen at a temperature of ?196 °C and mass flow rate of 0.074 kg·s?1. Numerical results reveal that with water/ethylene mixture the PV can withstand heat fluxes up to 360 W·cm?2, without its temperature exceeding 100 °C. For higher thermal fluxes (360–600 W·cm?2), cryogenic liquid nitrogen is found to prevent the PV overheating and, therefore, is an attractive coolant; however, it poses safety concerns due to its possible boiling. Finally, two additional cooling system designs are proposed, a heat sink with straight fins and another with copper pipes, which offer higher heat transfer areas, but are more difficult to manufacture, than the copper plate heat spreader.
关键词： Ultra-high power density,Copper plate heat spreader,Cooling system design optimization,Electronic device,Computational fluid dynamics (CFD)
更新于2025-09-23 15:21:01
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Pulsed laser ablation route assisted copper oxide nanoparticles doped in Polyethylene Oxide/Polyvinyl pyrrolidone blend for enhancement the electrical conductivity
摘要： Polyethylene Oxide/Polyvinyl pyrrolidone blend was doped by Copper Oxide Nanoparticles (CuONPs) prepared by laser ablation process. Synthesized Copper oxide nanoparticles were prepared by ablating pure copper plate immersed in DDW by nanosecond Nd:YAG laser in different times. PEO/PVP/CuONPs nanocomposites have been synthesized via casting technique. Effect of CuONPs doping on enhancing PEO/PVP have been obtained. The influence of various times of laser ablation on the properties of the synthesized nanocomposite films was analyzed via several techniques. SEM and XRD proved the interaction between PEO/PVP blend and CuONPs. The presence of the distinctive absorption peak at UV-Vis range at 277 nm was due to copper oxide surface plasmon resonance (SPR). The direct and indirect optical band gap values illustrate a decrease following doping of copper oxide inside PEO/PVP matrix. Dielectric constant and dielectric loss activity gradually diminished as the frequency rises. AC conductivity were increased as laser time increased.
关键词： Copper oxide nanoparticles,Pulsed laser ablation,Ac conductivity,PEO/PVP
更新于2025-09-23 15:21:01
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[IEEE 2019 20th International Conference on Electronic Packaging Technology(ICEPT) - Hong Kong, China (2019.8.12-2019.8.15)] 2019 20th International Conference on Electronic Packaging Technology(ICEPT) - Self-Assembled Copper Nanoclusters-Based White Light Emitting Diodes With High Performance
摘要： Metal nanoclusters, composed of a few to a hundred atoms, whose size is close to the Fermi wavelength of electrons, have become a new type of phosphor materials due to their unique electronic structure and excellent performance. And metal nanoclusters have been applied in various applications, such as bioimaging, chemical biosensing, optoelectronic devices, etc. At present, researchers have synthesized and studied gold and silver nanoclusters, but Au and Ag nanoclusters have one drawback: expensive. At the same time, copper nanoclusters have attracted people's attention because of their non-toxicity, large Stokes shift and economy. In this paper, we fabricated 1-dodecanethiol (DT)-capped self-assembled copper nanoclusters in colloidal solution with yellow light emission and characterized the prepared self-assembled copper nanoclusters by UV–visible spectra, TEM and PL characterization methods. Self-assembled copper nanoclusters were used as color conversion layers for the manufacture of white light-emitting diodes. The prepared white LED has good color properties, the color rendering index was 79.3, the CIE color coordinates located at (0.3213,0.3255) and the color temperature was 6067K. This indicates that copper nanoclusters show potential for applications in white lighting emitting diodes as a new type of low-cost and superior photoluminescent material candidates.
关键词： Copper Nanoclusters,Photoluminescence,White Light Emitting Diodes,Quantum Dots
更新于2025-09-23 15:21:01
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CuSCN as the Back Contact for Efficient ZMO/CdTe Solar Cells
摘要： The replacement of traditional CdS with zinc magnesium oxide (ZMO) has been demonstrated as being helpful to boost power conversion e?ciency of cadmium telluride (CdTe) solar cells to over 18%, due to the reduced interface recombination and parasitic light absorption by the bu?er layer. However, due to the atmosphere sensitivity of ZMO ?lm, the post treatments of ZMO/CdTe stacks, including CdCl2 treatment, back contact deposition, etc., which are critical for high-performance CdTe solar cells became crucial challenges. To realize the full potential of the ZMO bu?er layer, plenty of investigations need to be accomplished. Here, copper thiocyanate (CuSCN) is demonstrated to be a suitable back-contact material with multi-advantages for ZMO/CdTe solar cells. Particularly, ammonium hydroxide as the solvent for CuSCN deposition shows no detrimental impact on the ZMO layer during the post heat treatment. The post annealing temperature as well as the thickness of CuSCN ?lms are investigated. Finally, a champion power conversion e?ciency of 16.7% is achieved with an open-circuit voltage of 0.857 V, a short-circuit current density of 26.2 mA/cm2, and a ?ll factor of 74.0%.
关键词： zinc magnesium oxide,copper thiocyanate,CdTe,CuSCN
更新于2025-09-23 15:21:01
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Using a nanosecond laser to pattern copper nanowire-based flexible electrodes: From simulation to practical application
摘要： Copper nanowire (Cu NW) electrodes have shown promise for use in next-generation transparent conducting films due to their high electrical conductivity, low-cost solution-based synthesis processes, and high transmittance properties. Recently, the use of lasers for the modification of nanostructures has received considerable attention. Despite the advantages of laser machining such as producing any shape in an accurate, time-saving, non-contact process, the laser patterning of Cu NW electrodes has not been extensively studied, particularly the heat effect of the laser irradiation process on the flexible substrate. In this report, we present experimental and computational results of a selective and direct patterning process by using nanosecond pulsed laser irradiation. The experimental and simulation results were used to optimize the laser ablation parameters for the patterning process of the ultra-long Cu NW transparent electrodes so as to not damage the flexible substrates. Finally, a bifunctional flexible smart-window was fabricated to demonstrate a practical application of the laser-patterned Cu NW electrodes.
关键词： Copper nanowires,Laser patterning,Flexible substrate,Nanosecond pulsed laser,Flexible smart-window
更新于2025-09-23 15:21:01
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Laser-Microstructured Copper Reveals Selectivity Patterns in the Electrocatalytic Reduction of CO2
摘要： The local (electro)chemical environment largely influences the selectivity toward, for example, olefins or alcohols in the electroreduction of CO2 over copper (Cu)-based catalysts. However, this factor is mostly qualitatively understood. Here, by combining catalytic results from a set of laser-microstructured Cu electrodes with defined geometries and accurate modeling including bulk and local effects, we map the effect of local pH and CO2 concentration for the main products. We also show how our results are useful for device engineering.
关键词： CO2 electroreduction,CO2 concentration,selectivity patterns,copper catalysts,laser-microstructured electrodes,local pH
更新于2025-09-23 15:21:01
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Conditions for Quality Dimensions in Direct Laser Melting of Copper
摘要： This paper analyzes the effect of SLM parameters on mechanical characteristics and surface roughness of a single-component copper powder. The study reports on appropriate SLM conditions for a single-component copper powder; to form a layer a technique within layer-by-layer selective laser melting is suggested and comprises roughing, semi-finishing and finishing modes. The work establishes a range to vary surface roughness, porosity and ultimate compressive strength of a single-component copper powder by means of laser processing conditions. Rz is variable 332 to 689 μm, porosity ranges approximately 13-39%, and ultimate compressive strength is 8 to 104 МPа.
关键词： melting conditions,Selective laser melting,roughness,copper,quality,porosity,ultimate compressive strength,coagulation
更新于2025-09-23 15:21:01
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Investigation on the effects of laser parameters on the plasma profile of copper using picosecond laser induced plasma spectroscopy
摘要： Laser induced plasma generation and characterization, affected by laser parameters and sample physical properties, represent important phenomena in many fields of applications. In this work, we present new studies on the effects of an appropriate combination of laser wavelengths and pulse energies on the generated plasma characterization using a single shot picosecond Nd:YAG laser. The plasma plume of a pure copper sample has been generated by laser induced plasma spectroscopy (LIPS) using a single shot 170 ps laser pulse with wavelengths (266, 355, 532 and 1064 nm) and varying laser fluence (10–41 J/cm2). The spectral intensities of Cu I 324.75, 327.39, 515.32 and 521.82 nm have been observed. The plasma electron temperature and density have been determined from the Boltzmann plots and Stark-broadening profiles of the plasma spectral lines, respectively, assuming the local thermodynamic equilibrium (LTE) condition. It has been found that the electron temperature and electron density values increase from around 10,000 to 20,000 K and around 2 × 1017 to 1.5 × 1018 cm?3, respectively, with the increase in the laser wavelength and pulse fluence gradually. These observations can be understood due to the variations of mass-ablation rates, inverse-Bremsstrahlung, and photo-ionization with the studied pulse wavelength and pulse energy. The obtained results explore the opportunity to control specific generated plasma parameters by applying proper picosecond pulse parameters which can be considered in many fields of material science spectroscopic analysis and control the plasma interaction dynamics.
关键词： Stark-broadening,Picosecond,Boltzmann plot,Electron temperature,LTE,Laser induced plasma spectroscopy,Copper,Electron density,Plasma plume,LIPS
更新于2025-09-23 15:21:01
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Diagnosis of copper plasma by laser induced breakdown spectroscopy
摘要： In this paper influence of laser energy on the emission spectrum of laser copper-interaction and plasma parameter for plasma Copper by used a first harmonic generated wavelength of Nd:YAG exaction source. The metal plasma that had detection by HR4000 detection system (ocean optics) was use to different excited. plasma temperature via the Boltzmann plot diagram with measuring the electron density number by McWhirter CRITERION. Values of measuring (Ne), (Te) found between (61178776 K°) and (Ne) is (1.77*1015, 2.01*1015 cm-3) at 1064nm.
关键词： LIBS,Copper plasma,electron number density,self-absorption,plasma parameter
更新于2025-09-23 15:21:01