Copper Metal Layers Research Articles

Production, Characterization and Mechanical Behaviors of Electrolytic Metal-Coated Light Polymeric Cylinders for Photogravure Press Applications

Since precision engraving is essential for almost any product or application, it is important that the printing system produces smooth and clear prints. In this regard, the rollers are made of steel and polymeric materials. However, light cylinder production is economical, transportation costs are very low, and it provides ease of transportation and distribution for printing houses. However, regional chain orientations and cracks occur in the polymeric material on the conical surfaces of the cylinders with shafts longer than 1 m. Therefore, it is necessary to improve the surface properties of polymeric cylinder. In this study, electrolytic hard chromium (Cr) and soft copper (Cu) metal layers, conductive (Ni and Ag) paint and polyester coating were successfully fabricated on polymeric lightweight cylinders via electroplating, spraying and hand brushing techniques for photogravure press application. At the fabrication stage on the steel base cylinders, polyurethane has been molded by using an injection molding machine. In order to eliminate the porosities, where polyurethane takes place, polyester has been coated on the polymeric cylinder and consequently polyester has been painted with conductive dye to obtain the conductivity. Then Cu and Cr have been coated by using the electroplating method and gravured. At the end of final stage, the process has been completed with coating of Cr on the Cu layer/conductive paint/polyester coating/polyurethane substrate. Phase analysis, microstructures and mechanical properties of the obtained samples have been examined through XRD, SEM–EDS, surface roughness, microhardness, tensile, three-point bending, scratch and wear machines. As a remarkable result of these studies, correlations were established between the quality of the layers and the mechanical properties as innovative scientific approaches, and between the layers produced on an experimental basis and the samples produced on a fabrication basis, they were produced and used in high-quality multilayered architecture to engraving technology and then to the society because of its effectiveness.

Bionic hierarchical metalized thermally responsive dynamic daytime passive radiative cooling nanocomposites

Passive heat management technology holds significant promise in mitigating the fossil energy crisis. However, most current passive radiative cooling textiles merely reflect sunlight, causing unnecessary cooling in cold regions during winter and lacking dynamic control. Herein, we were inspired by chameleons to develop a temperature-sensitive passive heat management nanocomposite using a multi-layered assembly strategy. This nanocomposite consisted of the core layer of metal-coated fabric and the surface layer composed of polydimethylsiloxane (PDMS), hexagonal boron nitride (h-BN), and organic temperature-variable material (OTM). When the nanocomposite contained 15 wt% OTM, the average reflectance in the cold (15 °C) and hot (30 °C) modes was 47.66% and 80.92%, respectively. Additionally, the average emissivity was found to be 91.64% and 91.31% in the cold and hot modes, respectively. Significantly, the nanocomposite demonstrated cyclic stability in multiple temperature response tests. In practical experiments, it effectively reduced the temperature within a car and a small wooden house model by 14.0 and 7.1 °C, respectively. Moreover, the nanocomposite facilitated the accelerated ice melting at a rate of 10.85 ± 0.3 g within 1 h. Additionally, the presence of a copper metal layer in the 15 wt% OTM nanocomposite was found to contribute to antimicrobial efficiencies of 56% and 38% against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus), respectively. This nanocomposite possesses the potential to stimulate inventive designs in the forthcoming era of functional nanocomposites, owing to its dynamic radiative cooling, solar heating capabilities, and scalability.

High performance SPR sensor using 2-D materials: A treatise on design aspects, material choice and figure of merit

2D material-based surface plasmon resonance (SPR) sensors have piqued attention of the researchers due to their enhanced sensitivity. The performance characteristics of a 2D material-based SPR sensor in angular and spectral interrogation were extensively studied using simulations in this work. The performance parameters were studied with various existing configurations and a new design using Cu with 2D materials was proposed for enhanced performance. A treatise of various design aspects, material choices was performed to conclude on a sensor design with the highest figure of merit (FOM). Substituting the silver metal layer with a copper metal layer increased the FOM by around 3.3–3.6 times. Field profiles were also evaluated, resulting in a 1.15–1.17-fold improvement over the standard designs. The present study provides a detailed overview on the 2D material integrated SPR sensors and can be useful for development of high performance biosensors.

Bipolar Current Collectors of Cu/polymer/Al Composite for Anode‐Free Batteries

AbstractThe all‐in‐one design of cathode and anode is a promising strategy to improve energy density and assembly efficiency for lithium batteries. However, it is an important prerequisite to combine negative and positive current collectors in a single sheet. Here, an asymmetric structure of bipolar composite current collector (BCCC), thin copper (Cu) and aluminum (Al) metal layers respectively deposited on each side of a thin polyethylene terephthalate (PET) polymer substrate is developed. Unlike conventional metal foils, the electronically insulative polymer blocks electron transfer between the cathode and anode coated on each side of BCCC. Buckling‐based mechanics measurement and molecular simulation are conducted to quantitatively evaluate the interfacial strength of metal/polymer, which is enhanced by introducing an intermediate chromium (Cr) layer. For applications in anode‐free wound batteries, the integrated sheet of separator/cathode/BCCC can simplify the alignment of the electrodes during the winding process. Without special surface and electrolyte optimizations, a higher Coulombic efficiency (99.1%) and larger capacity retention (50.0%) are achieved after 100 cycles in the LiNi0.8Co0.1Mn0.1O2 anode‐free battery than the battery using Cu foils.

완전집적형 임피던스 변환 다중권선 90° 커플러의 설계

In this paper, a design methodology for a fully integrated impedance-transforming multi-winding 90° coupler is proposed. The operation of the proposed coupler was verified using measurement results. These couplers were fabricated using the WIN semiconductor InGaP/GaAs heterojunction bipolar transistor (HBT) process. To provide an impedance transformation, the proposed couplers were designed with 3, 4 and 5 turn coils for 50-, 75-, and 100-Ω impedance transformations, respectively. The center frequencies of each coupler were 5.5, 3.33, and 2.47 GHz. Two copper metal layers were combined together with a via to attain a high Q factor, and its improvement was analyzed. The measurement results show that the insertion losses of the proposed couplers are less than 0.37 dB and phase imbalances are less than 2.74°.

Thermal Stability of the Copper and the AZO Layer on Textured Silicon

Transparent conductive oxide (TCO) film is the most widely used front electrode in silicon heterojunction (SHJ) solar cells. A copper metallization scheme can be applied to the SHJ process. The abundance of zinc in the earth’s crust makes aluminum-doped zinc oxide (AZO) an attractive low-cost substitute for indium-based TCOs. No work has focused on the properties of the copper and AZO layers on the textured silicon for solar cells. This work deposited an aluminum-doped zinc oxide layer and copper metal layer on textured (001) silicon by a sputtering to form Cu/AZO/Si stacks. The structures of Cu/AZO/Si are characterized by scanning electron microscope (SEM), scanning transmission electron microscope (STEM), and energy-dispersive X-ray spectrometer (EDS). The results show that the copper thin film detached from AZO in the valley of the textured silicon substrate at a temperature of 400 °C. Additionally, the gap between the copper and AZO layers increases as temperature increases, and the 65 nm thickness AZO layer was found to be preserved up to 800 °C.

220-to-330-GHz Manifold Triplexer With Wide Stopband Utilizing Ridged Substrate Integrated Waveguides

This article reports a three-channel, noncontiguous, manifold multiplexer operating from 220 to 330 GHz, a 40% fractional operating bandwidth. The structure is designed and implemented using a set of ridged substrate integrated waveguides (SIWs). The ridged SIW improves the stopband bandwidth and reduces the overall structure size by 35% over a conventional SIW design. The triplexer utilizes an organic package substrate technology developed by Intel, featuring four thick copper metal layers and continuous trench vias in lieu of standard via fences, which significantly decrease the ohmic loss of the ridged SIW waveguides. Electromagnetic-circuit modeling and codesign techniques are adopted in the development of the triplexer structure. The fabricated triplexer is measured using banded millimeter-wave wafer probing and exhibits 3~7 dB of insertion loss in the passbands and better than 10 dB of average return loss for each of the channel filters. The measured stopband attenuation is better than 27 dB for all three channels.

Barrier performance of ITO film on textured Si substrate

Indium tin oxide (ITO) film is the most widely used as front electrodes in solar cells with a copper metallization scheme. No work has focused on the barrier properties of the ITO layer on the textured silicon for solar cells. In this work, a thin indium tin oxide barrier layer and copper metal layer were deposited on textured (001) silicon by a sputtering. The stacks present Cu/ITO/Si. The structures of Cu/ITO/Si characterized by scanning transmission electron microscope, energy-dispersive X-ray spectrometer, and powder X-ray diffraction. The results show that the stacks of Cu/ITO/Si can be preserved up to 600 °C. The 35-nm thickness ITO layer was found to be a diffusion barrier against Cu up to 600 °C. The copper thin films were agglomerated and formed the particle at a temperature of 700 °C. The failure of Cu/ITO/Si can be attributed to agglomerate copper thin films and breakdown of ITO thin films at a temperature of 700 °C.

Surface chemistry of copper metal and copper oxide atomic layer deposition from copper(ii) acetylacetonate: a combined first-principles and reactive molecular dynamics study.

Atomistic mechanisms for the atomic layer deposition using the Cu(acac)2 (acac = acetylacetonate) precursor are studied using first-principles calculations and reactive molecular dynamics simulations. The results show that Cu(acac)2 chemisorbs on the hollow site of the Cu(110) surface and decomposes easily into a Cu atom and the acac-ligands. A sequential dissociation and reduction of the Cu precursor [Cu(acac)2 → Cu(acac) → Cu] are observed. Further decomposition of the acac-ligand is unfavorable on the Cu surface. Thus additional adsorption of the precursors may be blocked by adsorbed ligands. Molecular hydrogen is found to be nonreactive towards Cu(acac)2 on Cu(110), whereas individual H atoms easily lead to bond breaking in the Cu precursor upon impact, and thus release the surface ligands into the gas-phase. On the other hand, water reacts with Cu(acac)2 on a Cu2O substrate through a ligand-exchange reaction, which produces gaseous H(acac) and surface OH species. Combustion reactions with the main by-products CO2 and H2O are observed during the reaction between Cu(acac)2 and ozone on the CuO surface. The reactivity of different co-reactants toward Cu(acac)2 follows the order H > O3 > H2O.

Impact of Copper Densities of Substrate Layers on the Warpage of IC Packages

STATS ChipPAC Inc., 47400 Kato Road, Fremont, CA 94538 (Received September 13, 2013: Corrected September 30, 2013: Accepted December 2, 2013)Abstract: In this paper, the impact of the copper densities of substrate layers on IC package warpage is studiedexperimentally and numerically. The substrate strips used in this study contained two metal layers, with the metal densitiesand patterns of these two layers varied to determine their impacts. Eight legs of substrate strips were prepared. Leg 1 toleg 5 were prepared with a HD (high density) type of strip and leg 6 to leg 8 were prepared with UHD (ultra high density)type of strip. The top copper metal layer was designed to feature meshed patterns and the bottom copper layer was designedto feature circular patterns. In order to consider the process factors, the warpage of the substrate bottom was measuredstep by step with the following manufacturing process: (a) bare substrate, (b) die attach, (c) applying mold compound(d) and post reflow. Furthermore, after the post reflow step, the substrate strips were diced to obtain unit packages andthe warpage of the unit packages was measured to check the warpage trends and differences. The experimental resultsshowed that the warpage trend is related to the copper densities. In addition to the experiments, a Finite Element Modeling(FEM) was used to simulate the warpage. The nonlinear material properties of mold compound, die attach, solder mask,and substrate core were included in the simulation. Through experiment and simulation, some observations wereconcluded. Keywords: warpage, substrate layers

Morphology and Thickness Control of Thin Copper Films Prepared by Electrochemical Deposition onto Mo-sputtered Stainless Steel Substrates

Chalcopyrite thin film solar cells of copper (Cu), indium (In), gallium (Ga) and selenium (Se) (CIGS) are receiving much attention, because they show high efficiency and longterm stability. 1 Methods to prepare CIGS light absorber layers include co-evaporation of elemental sources, 2 physical vapor deposition, 3 printing and electrochemical deposition. 4 Among those, electrochemical deposition is considered as an excellent technique for large area processing with good uniformity, low cost, and high material yield. 5 Electrodeposition of CIGS precursor films can be performed by using either single step or multistep process. Although Bhattacharya et al. have reported the development of a 15.4% efficiency CIGS cell by employing a single-bath electrochemical deposition following physical vapor deposition, 6 no other laboratory has reproduced it. The multistep process can be two or three stage process; some examples of such stacks are like Cu/In/Ga, Cu-Ga/In/Se, Cu/In/Ga-Se, Cu/In-Se/Ga-Se, etc. 7-9 For successful industrialization of CIGS solar cells, control of metal layers is required in morphology, thickness, and production speed. The objective of this study was to fabricate the targeted copper thin film onto Mo/SUS substrates by electrochemical deposition for CIGS thin film solar cell precursor. Morphology and thickness of copper thin film onto the Mo/SUS are very important factors because film’s surface condition can affect electrochemical deposition of the next layers of In, Ga, and Se before thermal selenization process. In this work, we wish to report our preliminary work on the electrochemical conditions that can produce a uniform thin copper metal layer onto the Mo sputtered stainless steel (Mo/SUS) flexible substrate for short time (sec). Mo/SUS substrate has the advantages of weight lighter than soda lime glass, of installation to the building integrated photovoltaic and of roll-to-roll manufacturing leading to substantial cost reductions due to enhanced productivity. All chemicals were analytical grade. Double-distilled water was used throughout. The electrochemical experiment was performed in a freshly prepared 0.1, 0.5 and 1 M CuSO4 baths containing various concentrations of (0.1, 0.5, 1, 1.5 M) H2SO4. Two-electrode configurations were used for deposition of Cu thin film. Hull cell test was performed in order to find the current density. The 100 × 100 mm 2 Mo/

Integrated High-Frequency Power Converters Based on GaAs pHEMT: Technology Characterization and Design Examples

The potential of GaAs pHEMT technology for high-frequency power-switching applications is discussed within the context of integrated power supplies for portable wireless systems. Various technology considerations are presented, including the optimization of the power-switching transistor and passives integration. Two design examples for integrated dc-dc converters are implemented in a 0.5-μm GaAs E/D pHEMT process. The first uses coupled inductors to reduce the current ripple and enhance the dynamic performance of the converter. The two-phase, 0.5 A/phase converter occupies 2 mm × 2.1 mm without the output network. An 8.7-nH filter coupled inductor is implemented in 65-μm-thick top copper metal layer, and flip-chip bonded to the dc-dc converter board. The presented converter converts 4.5-V input to 3.3-V output at 150-MHz switching frequency with a measured power efficiency of 84%, which is one of the highest efficiencies reported to date for similar current/voltage ratings. The second example is a hysteric controlled, 100-MHz switching frequency single-phase GaAs pHEMT buck converter designed to drive power amplifier loads. The design can deliver up to 37-dB·m output power and has a peak efficiency of 88% and a 3-dB bandwidth of 14.5 MHz.

High efficiency, high switching speed, AlGaAs/GaAs P-HEMT DC–DC converter for integrated power amplifier modules

This paper presents a high efficiency, high switching frequency DC---DC buck converter in AlGaAs/GaAs technology, targeting integrated power amplifier modules for wireless communications. The switch mode, inductor load DC---DC converter adopts an interleaved structure with negatively coupled inductors. Analysis of the effect of negative coupling on the steady state and transient response of the converter is given. The coupling factor is selected to achieve a maximum power efficiency under a given duty cycle with a minimum penalty on the current ripple performance. The DC---DC converter is implemented in 0.5 μm GaAs p-HEMT process and occupies 2 × 2.1 mm2 without the output network. An 8.7 nH filter inductor is implemented in 65 μm thick top copper metal layer, and flip chip bonded to the DC---DC converter board. The integrated inductor achieves a quality factor of 26 at 150 MHz. The proposed converter converts 4.5 V input to 3.3 V output for 1 A load current under 150 MHz switching frequency with a measured power efficiency of 84%, which is one of the highest efficiencies reported to date for similar current/voltage ratings.

Formation and its mechanism of copper metal layers at surface by annealing in reduced atmosphere in CuO–Li 2O–Nb 2O 5–SiO 2 glass

A trace amount (0.5 mol%) of CuO-doped 40Li 2O–32Nb 2O 5–28SiO 2 glass (mol%) exhibits the formation of copper metal layers at the glass surface by annealing at temperatures (530 °C) below the glass transition temperature (544 °C) in the reduced atmosphere of 7% H 2–93%Ar. The coordination state of copper ions is examined from optical absorption and Fourier transform infrared (FT-IR) spectrum measurements, indicating the formation of Si–OH and Si–H bonds due to the diffusion of hydrogen into the inside of the glass and the reduction of Cu + and Cu 2+ ions. The mechanism of the formation of copper metals at the surface is proposed, in which the key points are the reduction of Cu 2+ to Cu + ions due to the hydrogen and the migration of Cu + ions in the interior of the glass to the surface. The first finding on copper metal layers at the glass surface might have a potential for practical applications such as electrodes in glass.

The role of copper in ZnO/Cu/ZnO thin films for flexible electronics

ZnO/Cu/ZnO multilayer structures with very high conductivity have been obtained by magnetron sputtering. The Hall resistivity of the films was as low as 6.9×10−5 Ω-cm with a carrier concentration of 1.2×1022 cm−3 at the optimum copper layer thickness. The conduction mechanism has been explained in terms of metal to oxide carrier injection at low copper thickness and metal layer conduction at higher Cu thicknesses. The peak transmittance of the films is 88% and the photopic averaged transmittance is 75%. Optical transmission behavior of the films involves absorption by copper due to d-band to Fermi-surface transitions at short wavelengths and reflectance combined with scattering losses at long wavelengths. A Burstein–Moss shift in the band gap of the films is seen to take place with increase in thickness of the copper layer. The Haacke figure of merit has been calculated for the films with the best value being 8.7×10−3 Ω−1. Pole figure results reveal that the copper midlayer acts as a hindrance to (002) ZnO texturing rather than as a seed layer. These results also confirm the mechanism of conduction. The results of the study assume further significance because annealing at 150 °C for up to 24 h in a reducing (Ar+5% H2) ambient was found to have negligible effect on the properties of the films.

Role of polymer chain end groups in plasma modification for surface metallization of polymeric materials

How to improve adhesion between poly(oxybenzoate-co-oxynaphthoate) (Vecstar OC and FA films) and copper metal by Ar, O2, N2 and NH3 plasma modification was investigated. The mechanism of adhesion improvement is discussed from the viewpoint of chemical and physical interactions at the interface between the Vecstar film and copper metal layer. The adhesion between Vecstar OC film and copper metal was improved by chemical rather than physical interactions. Polymer chain end groups that occur at Vecstar OC film surfaces contribute effectively to adhesion. This improvement in adhesion is due to interactions between copper metal and OC groups formed by plasma modification. Aggregation of the OC groups to the copper metal/Vecstar OC film interface is a key factor for good adhesion. From this aspect, heat treatment of plasma-modified Vecstar OC films on glass plates is effective in the aggregation, and the peel strength for the copper metal/Vecstar OC film system reached 1.21 N (5 mm)−1. Copyright © 2009 Society of Chemical Industry

Self-assembled monolayer fiducial grids for spatial-phase-locked electron-beam lithography

The authors characterize a new fiducial grid based on a self-assembled monolayer (SAM) that is well suited to low-energy (⩽10keV) spatial-phase locked electron-beam lithography (SPLEBL). SAMs significantly alter the secondary electron yield of the metal films on which they are formed. In addition, SAMs are not expected to strongly scatter the primary beam, even at low energies, because they are less than 2-nm-thick and are composed of low atomic number elements. In this work the authors evaluate the signal-to-noise ratio (SNR) of SAM grids on gold and copper coated electron-beam resist. 400nm period octadecanethiol fiducial grids were microcontact printed onto the gold and copper metal layers using polydimethylsiloxane stamps. Gold serves as a model system and provides excellent SNR; however, its strong forward scattering makes it impractical in many applications. Copper offers reduced forward scattering but exhibits inverted secondary electron contrast and greatly reduced SNRs. In all cases, SNR decreases with increasing beam energy as overall secondary electron yield decreases. These results suggest that SAM fiducial grids are promising for low-energy SPLEBL; however, further optimization of the interlayer and SAM composition is warranted.

Electrode reactions in Cu–Pt coated ionic polymer actuators

Abstract Composite actuators consisting of sheets of the solid polymer electrolyte (similar to Nafion®) with Cu2+ counter ions inserted and coated with platinum and copper metal layers (so-called ionomeric polymer–metal composites; IPMCs) have been synthesised and their electromechanical performance upon actuation has been monitored. Resistance measurements on the electrodes show that the electrical conductivity of the membranes metal surface increases on the cathode side during the actuation process, contradictory to the situation when Cu is absent from the metal coating. This phenomenon is explained by the subsequent reduction of Cu2+ ions on the cathode upon actuation; Cu layer growth in this side prevents it from cracking and decreases its electrode resistance. The phenomenon opens up for longer lifetimes for Cu-based IPMCs. However, additional problems with Cu layer oxidation and Cu dendrite growth on the electrodes should be considered.

Flexible and lithography-compatible copper foil substrates for ferroelectric thin films

A process has been developed for preparing a low surface roughness copper foil by evaporation and subsequent peel-off of copper metal layers on glass slides. These 15 micron thick substrates exhibited roughness values between 1 and 2 nm root-mean-square (RMS) and 9 nm RMS over 25 μm 2 and 100 μm 2 analysis areas, respectively. The deposition and crystallization of barium strontium titanate layers were demonstrated on these smoother variant foils. The fully processed dielectric layers exhibited field tunability greater than 5:1, and could withstand fields in excess of 750 kV/cm. High field loss tangents below 0.007 were observed, making these materials excellent candidates for microwave devices. Finally, a process of lamination and contact lithography was used to demonstrate patterning of micron-scale features suitable for microwave circuit element designs.

Electrosprayed and selenized Cu/In metal particle films

Nano-particulate copper and indium metal layers of 1–2 μm have been deposited by non-vacuum techniques such as doctor blade, screen printing and electrospray using alcoholic suspension pastes. Electrospray showed a high efficiency of material usage and yielded the most uniform morphology. The metal precursor layers were subjected to a thermal treatment (500–600 °C) in selenium vapor to convert the porous metal layers into CuInSe 2 compound layers. The chemical conversion, investigated by X-ray diffraction, showed the presence of the In 2O 3 impurity phase in the precursor as well as in the selenized layers.