Copper Patterns Research Articles

Pre-monsoon spatial distribution of available micronutrients and sulphur in surface soils and their management zones in Indian Indo-Gangetic Plain.

The efficient (site-specific) management of soil nutrients is possible by understanding the spatial variability in distribution of phyto-available nutrients (here after called available nutrients) and identifying the soil management zones (MZs) of agricultural landscapes. There is need for delineating soil MZs of agricultural landscapes of the world for efficient management of soil nutrients in order to obtain sustainability in crop yield. The present study was, therefore, undertaken to understand the spatial distribution pattern of available micronutrients (zinc (Zn), boron (B), iron (Fe), manganese (Mn) and copper (Cu)), available sulphur (S), and soil properties (soil acidity (pH), electrical conductivity (EC) and organic carbon (SOC) content) in soils of intensively cultivated Indo-Gangetic Plain (IGP) of India and to delineate soil MZs for efficient management of soil nutrients. Totally, 55101 soil samples from 0–15 cm depth were obtained from 167 districts of IGP during 2014 to 2017 and were analysed for different soil parameters. Soil pH, EC and SOC content varied from 4.44 to 9.80, 0.02 to 2.13 dS m-1 and 0.10 to 1.99%, respectively. The concentration of available Zn, B, Fe, Mn, Cu and S varied from 0.01 to 3.27, 0.01 to 3.51, 0.19 to 55.7, 0.05 to 49.0, 0.01 to 5.29 and 1.01 to 108 mg kg-1, respectively. Geostatistical analysis resulted in varied distribution pattern of studied soil parameters with moderate to strong spatial dependence. The extent (% area) of nutrient deficiencies in IGP followed the order: S > Zn > B > Mn > Cu > Fe. Principal component analysis and fuzzy c-means clustering produced six distinctly different soil MZs of IGP for implementation of zone-specific soil nutrient management strategies for attaining sustainability in crop yield. The developed MZ maps could also be utilized for prioritization and rationalization of nutrients supply in IGP of India.

Direct Copper Patterning at High Deposition Rate By Using Environmentally Compatible Electroplating Process

Electroplating has been an important process to produce electronic devices, automotive parts, decorative materials and so on. In contrast to that, plating is endowed with environmental issues originated from exhaust fluids and acid mists. Therefore, it is limited to construct new production line in spite of necessity of plating. Moreover, it is difficult to improve productivity drastically due to completely established plating technology in 21th century. To break down demerits of conventional electroplating, we focus on the fundamental issue regarding with the plating process that can be performed in electrolyte bath. Recently, we have developed novel electroplating process named solid electrodeposition (SED), which is characterized by metal ion electrophoresis through solid electrolyte membrane1). This process has unique deposition behavior that the metal deposition on substrate proceeds only on contact area with the membrane, like a stamping process. The SED has a merit of reducing amount of exhaust fluids as well as direct patterned deposition reflecting the membrane shape. Therefore, we believe that SED is highly promising process to metallize the substrate instead of the conventional electroplating. In this study, we report on copper deposition mechanism and direct fine pattering process by applying SED.We evaluate the limitation of copper deposition rate under controlled process parameters. As a result of that, the maximum deposition rate reaches over 0.63A/dm2 (14μm/min), which should be relatively higher than conventional one. The impressive value is originated from metal transfer mechanism into membrane as well as the device configuration. The metal deposition proceeds on solid-solid interface between membrane and substrate so that no diffusion layer exist near the substrate2). Moreover, the distance between anode and cathode can be shorten because the membrane preserves electrolyte solution. The copper film deposited from electrolyte solution without additives exhibits relatively smooth and minute surface morphology. This may be because membrane contacted on substrate restricts abnormal Cu growth due to contact pressure.SED has a merit for direct patterned deposition reflecting membrane shape, but it is not easy to fabricate fine patterns without masking. Therefore, it is limited to apply high-end parts such as printed circuit boards and sensor devices. To overcome this problem, we have developed direct fine patterning process by combining SED with dry coating and etching technologies. Figure 1 shows schematic diagram and photographs of each step. Firstly, the metal thin layer is formed on substrate by means of sputtering (electrode layer). Secondary, silver nanoparticles are printed as fine circuit patterns and sintered at optimal temperature (seed layer). Thirdly, copper was selectively deposited on seed layer by means of SED, which utilizes the potential difference between electrode and seed layers. The SED proceeds through isotropic growth along vertical direction because the deposition occurs on the surface of seed layer contacted with the membrane. Therefore, SED can produce relative thick and fine patterns following line width of seed layers. Finally, the bear electrode layer is etched away by plasma exposure. We believe that this approach is highly promising process to fabricate circuit pattern in terms of cost (simple step) and environmental (no exhaust fluids) point of view. 1. H. Yanagimoto, R. Mori, K. Okamoto and J. Murai, F01-994, 236nd ECS Meeting.2. Y. Narui, Y. Hoshi, I. Shitanda, M. Itagaki, H. Yanagimoto, M. Hiraoka and H. Iisaka, E01-920, 232nd ECS Meeting. Figure 1

Demonstration of wideband metal mesh filters for submillimeter astrophysics using flexible printed circuits.

We developed a wideband quasi-optical band-pass filter covering 170-520 GHz by exploiting the recent advancements in commercially available flexible printed circuit (FPC) fabrication technologies. We designed and fabricated a three-layered stack of loaded hexagonal grid metal meshes using a copper pattern with a narrowest linewidth of 50µm on a polyimide substrate. The measured frequency passband shape was successfully reproduced through a numerical simulation using a set of parameters consistent with the dimensions of the fabricated metal meshes. FPC-based metal mesh filters will provide a new pathway toward the on-demand development of millimeter/submillimeter-wave quasi-optical filters at low cost and with a short turnaround time.

Mechanism of a catalytic silver(I)-complex: assisted electroless deposition of inductance coil on poly(ethylene terephthalate) film

In this work, silver nitrate, thiourea, bisphenol A diglycidyl ether (BADGE), and propylene glycol methyl ether (PM) were selected for designing a silver(I)-complex to trigger the deposition of inductance coil on PET film through electroless copper plating. The most stable silver(I)-complex structure is formed when the ratio of thiourea molecules and silver ions is 3 to 1 by quantum chemical calculations based on density functional theory (DFT). Meanwhile, XRD test demonstrates that the white precipitate crystallized from PM solution of thiourea and silver nitrate is [Ag(SC(NH2)2)3]NO3, which is consistent with theoretical calculations. The cross section of PET film with copper patterns and interconnection holes characterized by metallurgical microscope proves that the silver(I)-complex is able to initiate copper deposition on the surface and through hole wall of PET film. The measured inductance values at operating frequency from 1 to 50 MHz indicate that the fabricated flexible inductor is capable of being integrated into flexible electronics when the bending angles are within 45°. Additionally, the inductor can also be utilized as an angel sensor when the bending angles are in the range of 60° to 180° at 10 MHz.

Synthesis and characterization of copper ink and direct printing of copper patterns by inkjet printing for electronic devices

Among the conventional metallic inks used in the printing process, silver exhibits high conductivity and thermal stability. Nevertheless, due to the high cost of silver, it cannot be extensively used for the fabrication of inks. As a competitive alternative, copper can be considered as a substitute for silver; however, copper ink oxidizes under certain atmospheric conditions. To meet these shortcomings, a cost effective, highly conductive, and oxidation-free copper-based ink has been synthesized in this study, wherein, oxidation of the copper particles in the copper-based ink was prevented by using copper complexes. The copper ink thus fabricated was printed on chemically treated Si/SiO2 substrates followed by the characterization of the printed copper films. The results of this study confirmed that the synthesized copper ink exhibited properties suitable for its use in the inkjet printing process for fabrication of various electronic devices.

Nanocomposite materials based on magnesium oxide and metal nanoparticles

The conditions and the patterns of copper and nickel nanoparticles formation by direct reduction from aqueous solutions of their salts in nitrogen atmosphere were studied, and nanocomposite materials based on magnesium oxide and metal nanoparticles coated with protective oxide shell were obtained. The obtained materials are of interest as sorbents for the purification of aqueous media from toxic impurities, as well as catalysts in organic synthesis, in particular for the production of methanol from carbon dioxide. Phase composition, thermal stability, microstructure of nanocomposites, as well as their sorption properties, were studied. The powders of magnesium oxide and nanocomposites based on it were found to have high sorption capacities with respect to lead and chromium ions – up to 2989.0 and 499.9 mg/g, respectively.

High‐Viscosity Copper Paste Patterning and Application to Thin‐Film Transistors Using Electrohydrodynamic Jet Printing

Direct patterning of copper (Cu) electrodes through a noncontact electrohydrodynamic (EHD) jet printing process is developed to overcome the drawback of printing mechanisms such as high viscosity in inkjet printing. Printed Cu lines with a width of about 40 μm are obtained from Cu paste with a viscosity of 4000 cPs using an additive. The effect of the operating parameters on jetting modes and printed patterns is investigated. The electrical property of the printed Cu layer shows a low resistivity of 8 × 10−4 Ωm after sintering under vacuum compared with air annealing. Solution‐processed zinc tin oxide (ZTO) thin‐film transistors (TFTs) with vacuum‐annealed Cu source and drain (S/D) electrodes are fabricated with comparable characteristics, such as an average effective mobility in the saturation region (μ) of 0.50 cm2 V−1 s−1, an on‐to‐off current ratio (Ion/Ioff) of 5.5 × 105, and a subthreshold slope (SS) of 3.35 V decade−1. These results demonstrate the potential of EHD jet‐printed Cu for application in electronic devices.

Movement Disorder in Copper Toxicity Rat Model: Role of Inflammation and Apoptosis in the Corpus Striatum.

The pattern of copper (Cu) toxicity in humans is similar to Wilson disease, and they have movement disorders and frequent involvement of corpus striatum. The extent of cell deaths in corpus striatum may be the basis of movement disorder and may be confirmed in the experimental study. To evaluate the extent of apoptosis and glial activation in corpus striatum following Cu toxicity in a rat model, and correlate these with spontaneous locomotor activity (SLA), six male Wistar rats were fed normal saline (group I) and another six were fed copper sulfate 100 mg/kgBWt/daily orally (group II). At 1 month, neurobehavioral studies including SLA, rotarod, and grip strength were done. Corpus striatum was removed and was subjected to glial fibrillary acidic protein (GFAP) and caspase-3 immunohistochemistry. The concentration of tissue Cu, total antioxidant capacity (TAC), glutathione (GSH), malondialdehyde (MDA), and glutamate were measured. Group II rats had higher expression of caspase-3 (Mean ± SEM 32.67 ± 1.46 vs 4.47 ± 1.08; p < 0.01) and GFAP (41.81 ± 1.68 vs 31.82 ± 1.27; p < 0.01) compared with group I. Neurobehavioral studies revealed reduced total distance traveled, time moving, the number of rearing, latency to fall on the rotarod, grip strength, and increased resting time compared with group I. The expression of GFAP and caspase-3 correlated with SLA parameters, tissue Cu, GSH, MDA, TAC, and glutamate levels. The impaired locomotor activity in Cu toxicity rats is due to apoptotic and inflammatory-mediated cell death in the corpus striatum because of Cu-mediated oxidative stress and excitotoxicity.

Sorption of Copper(II) Ions with Nanosized Magnesium Phosphate

A new approach to the preparation of a nanosized sorbent based on magnesium phosphate has been developed. The patterns of copper(II) ions sorption with nanosized magnesium phosphate from aqueous solutions have been investigated. The sorption parameters have been determined, and the kinetics and mechanism of the processes have been elucidated. The high sorption ability of the nanoscale sorbent has been shown in comparison with existing sorbents based on magnesium phosphate.

Compatible Ag+ Complex-Assisted Ultrafine Copper Pattern Deposition on Poly(ethylene terephtalate) Film with Micro Inkjet Printing.

Firm immobilization of catalysts on the predesigned position over substrates is an essential process for producing flexible circuits by the electroless deposition (ELD) process. In this work, a compatible Ag+ complex was developed and directly printed on the poly(ethylene terephtalate) (PET) film through a micro inkjet printing instrument to trigger the deposition of ultrafine copper patterns with approximately 20 μm in width. Morphological and elementary characterization verified that the nanosized silver catalyst was uniformly distributed in the bridge layer, which could enhance the adhesion between the PET film and deposited copper patterns. Moreover, after 30 min of ELD, the copper patterns exhibited a low resistivity of 2.68 × 10-6 Ω·cm and maintained considerable conductivity even after 2000 times of cyclical bending. These interesting conductive and mechanical features demonstrate the tremendous potential of this Ag+ complex-assisted copper deposition in the interconnection of high-density integrated flexible electronics.

An EMI Suppression Method in SiC Half-bridge Power Module Design

Abstract This paper presents a 1200V/24A SiC half-bridge power module with ultra-low parasitic capacitance and inductance for low CM EMI. This module is improved from a stacked substrate hybrid packaging structure by optimizing the copper pattern. The parasitic capacitance reduction methods and the trade-off optimization for geometrical parameters are given. The parasitic capacitance of the output node is reduced by 70% compared to the original module. The parasitic capacitance and inductance of the proposed module are 6.8pF and 5.5nH respectively. The EMI simulation shows the proposed module can reduce CM EMI by about 9 dB, while the EMI test result shows a maximum of 6 dB reduction.

Fine pitch features laser direct patterning on flexible printed circuit board

Laser direct copper patterning of fine pitch features on polyimide flexible substrate was investigated. On such thin substrates (generally below 0.1 mm), laser parameters should be optimized in order to minimize the damage beneath the conductive layer, as it might lead to severe robustness issues. We selected several parameter sets and compared them in terms of damage depth, feature sizes and edge straightness. On bare copper PCBs (Printed Circuit Boards), we managed to limit the average damage to a depth of 8 µm, while getting features’ characteristics significantly better than what would be obtained with standard chemical etching. We also demonstrated alternative parameter sets that allow to obtain ultra-thin features or very straight edges at the cost of deeper damage in the substrate.Two application cases were studied. Firstly, we realized 2D planar coils. Due to a higher number of turns at equivalent surface areas, laser patterning of a spiral coil results in inductance value one order of magnitude larger when compared with standard chemical etching (39 µH vs. 4 µH for a 113 mm² coil). Such coils can advantageously be used in sensing or inductive charging applications, when flexibility and/or ultra-thin profile is required. Secondly, we demonstrated the feasibility of fine-pitch bond pads for COF (Chip-On-Flex) applications. We achieved a bond pad pitch of 80 µm (60 µm pad dimension / 20 µm pad clearance). Laser direct pattering is presented as a single step and purely dry alternative to high-end PCB manufacturing processes.

Copper Electrodeposition on Textile for Wearable Electronics

Two main tasks in fabricating a circuit is to pattern the interconnections and soldering elements to the patterned conductive traces. Using copper growth electrodeposition assisted by hydrogen evolution as a technique for integration of electronic elements and circuits in fabrics and flexible substrates particularly useful for soldering electronic components, representing an advantage over conventional methods and providing a high quality of the deposits requiring relatively inexpensive equipment. This method has shown high rate of deposition and formation of nanostructures, expected to anchor to the fibers of a fabric for enhanced stability of the structure. Moreover, the technique has proven to be reliable for soldering electronic components at room temperature. A copper pattern can be achieved over a MWCNTs coating by the copper growth deposition in the electrochemical cell after electrolysis is reached in the cell with the aqueous solution of Cu2+ and H2SO4. Cu2+ions interact with hydrogen allowing the formation of the reaction product by the application of voltages above 1.0V. The electrodeposition parameters and the quality of the copper being deposited will be analyzed to find the optimum conditions for fast copper deposition and adhesion to the fabric structure and also will be tested for soldering simple electronic elements and it will be studied to be more resilient during laundry.

Copper electrochemical migration growth in an air HAST

High performance electronics require printed circuit boards (PCBs) with an extremely narrow pitch between adjacent copper patterns. However, copper electrochemical migration in these fine-pitch PCBs is a major source of failure. This phenomenon is typically identified using a highly accelerated temperature and humidity stress test (HAST) in which the water vapor pressure inside a chamber is increased along with the temperature and humidity. However, a side effect of this is that little air remains in the chamber despite air being required when replicating actual environments. This can be overcome by using an air HAST system that includes air inputs in its chamber. In our experiments, we analyzed the copper electrochemical migration on coupon samples with a 125 μm pitch at temperatures above 120 °C under various air pressures. We then compared the results for the air HAST, HAST, and high temperature and high humidity (85 °C/85% R.H.) tests by plotting each lifetime in the form of a Weibull distribution. Upon inspection, the cross-sectional microstructures of the copper electrochemical migration were seen to vary between the HAST and air HAST methods due to differences in the growth mechanism of the copper electrochemical migration.

Fabrication of Copper Circuit Pattern By Using Solid-Electrodeposition Process

Recently, automotive industry faces to revolution originated from the concept of Connected, Autonomous, Shared and Electric (CASE). For future society, it is noted that electric devices should be increasingly important components because a large number of the devices is indispensable to put CASE in practice. In electric devices, printed circuit boards (PCBs) are particularly key materials, which require further high density wiring as well as cost reduction. The fine patterned PCBs is often fabricated by semi-additive process. However, it is not easy to achieve finer pattering, owing to limitation of photolithographic resolution as well as residual palladium and/or copper metal in etching area. Regarding with the fabrication cost, the drastic reduction cannot be expected without changing process flow because semi-additive process is one of the mature technologies. In addition to that, the exhaust water generated from developing, electroplating, etching and rinsing processes causes serious environmental issues on nature, almost all of which are related to masking and electro/electroless plating processes. Therefore, it is urgently necessary for CASE to develop simple process without masking and conventional plating. We have developed novel electrodeposition process named solid electrodeposition (SED) which is characterized with metal ion electrophoresis through solid electrolyte membrane. The present SED apparatus is shown in Fig. 1. The head part composed of anode electrode, metal solution and the membrane is settled on the tip of press apparatus. The head part contacts with substrate under constant pressure and then a voltage is applied between anode electrode and cathode substrate. The metal deposition proceeds on solid-solid interface between membrane and substrate. It is important to note that cation exchangeable polyelectrolyte is used for membrane, i.e., metal ion can diffuse through ion-exchange reaction. When this system is accumulated into small probe system, this process enables electrodeposition of metals only by attaching the membrane surface into the substrate in a serial patterning manner. Moreover, SED has a merit of relatively high deposition rate, which is characterized with effective mass transfer mechanism of metal ion into membrane. We believe that SED can be highly potential process to dissolve not only the cost but also the environmental issues for current fabrication process of electronic elements. In the current study, we report on the fabrication of PCBs by using SED process. Although SED process can apply for selective deposition, an area of which depends on contact area of membrane used for deposition, it is difficult to match membrane size with fine patterns. Therefore, the patterned seed layer is printed on the substrate before SED process. The deposited copper patterns completely reflect underlying seed patterns without widening metal lines. This is because copper predominantly deposits along height direction, presumably due to selective growth of copper at solid interface. In this contribution, we will report the characteristics of SED process and novel process to fabricate circuit patterns without using masking and rinsing process. Figure 1

Copper micro-electrode fabrication using laser printing and laser sintering processes for on-chip antennas on flexible integrated circuits

Recent advances in flexible electronics have highlighted the importance of high throughput, digital additive microfabrication techniques. In this work, we demonstrate the combination of laser printing and laser sintering of a novel copper nanoparticle ink onto flexible substrates in order to produce oxide free conductive copper patterns in ambient atmospheric conditions. The printed patterns exhibit high reproducibility, very low resistivity (about 2x bulk), and negligible oxidation according to Raman spectroscopy. The process has been employed for the fabrication of an on-chip antenna on a flexible substrate for use in combination with a flexible circuit, in applications where a small form factor and simplicity of integration are required alongside ultra-low cost, e.g. consumable tagging.

Rapid low temperature sintering in air of copper submicron particles with synergistic surface-activation and anti-oxidative protection

The technology to sinter copper inks in air is beneficial for the applications in flexible printed electronics. However, copper based ink could hardly produce conductive copper patterns when sintered in air, because copper is easily oxidized. In this study, a convenient fabrication process for conductive copper films with a simple heat treatment on hotplate in air was successfully developed. The ink was prepared by mixing copper submicron particles with formic acid and an amino-alcohol. The copper oxide on the surface of untreated copper submicron particles was converted to decomposable copper formate. More importantly, the copper submicron particles could be activated by the chemisorbed HCOOH to sinter at low temperatures. 3-Dimethylamino-1,2-propanediol (DMAPD) was introduced to protect copper from oxidation when sintered in air. In addition, DMAPD could promote the decomposition of copper formate by forming copper–amine complex. A resistivity of 54 ± 2 μΩ cm was obtained after sintered at 200 °C for 50 s (63 ± 4 μΩ cm for only 10 s). This simple, convenient and rapid sintering of submicron copper inks in air provides an alternative fabrication method of copper patterns in printed electronics.

Uptake and exportation of micronutrients in high productivity corn fields

High yield corn has an increased demand for micronutrients, which requires updating knowledge of the nutritional demand patterns of the crop, especially under high production conditions. The objective of the currentstudy was therefore to determine the absorption and export patterns of copper (Cu), manganese (Mn), zinc (Zn) and iron (Fe) for high yield corn crops. Fifteen corn fields with high productive potential were sampled in the Alto Paranaíba, region, Minas Gerais, in the agricultural year 2014-2015. The following&#x0D; variables were evaluated: productivity, plant population, rows of grain per ear, grain per row, grain per ear, mass of one thousand grains, vegetation dry mass, dry mass of grains and total dry mass of the plant, besides the accumulation of micronutrients in the vegetative part and grains, and total micronutrient accumulation&#x0D; per whole plant. The grain and Cu, Mn, Zn and Fe harvest indices were also calculated. The data were submitted to descriptive statistics, Pearson coefficient linear correlation was calculated at the to 5% level and submitted to regression analysis. Cu and Zn absorption and export increase linearly with increased&#x0D; productivity. Micronutrient accumulation in high productivity maize is, in decreasing order, in the vegetative part: Fe&gt; Mn&gt; Zn&gt; Cu; while in the grains and in the whole plant: Fe&gt; Zn&gt; Mn&gt; Cu. Zn is the micronutrient with the highest harvest index.

Selective Electroless Copper Deposition by Using Photolithographic Polymer/Ag Nanocomposite

This paper presents a novel, direct, selective, vacuum-free, and low-cost method of electroless copper deposition, allowing additive patterning of nonconductive surfaces. Ag nanoparticles (NPs) synthesized inside a photosensitive polymer are acting as seeds for electroless copper deposition. The resulting copper film surface morphology was studied with scanning electron microscopy. Copper films were shown to display a rough grainlike structure, covering substrate uniformly with good metal-substrate adhesion. Copper thickness was studied as a function of the plating time, temperature, and Ag NPs seed concentration. A maximal copper thickness of ${0.44}\,\pm \,{0.05}~\mu \text{m}$ was achieved when plated at 30 °C with 0.4 M Ag(I). The minimum feature resolution of copper patterns, grown with 0.025- and 0.1-M silver salt, is attained down to ${10}~\mu \text{m}$ . The maximum electrical conductivity of the copper film prepared with 0.025-, 0.1-, and 0.4-M Ag(I) approaches ( ${0.8}\,\pm \,0.1) \times {10}^{{7}}$ S/m, ( ${1.1}\,\pm \,{0.1}) \times {10}^{{7}}$ S/m and ( ${1.6}\,\pm \, {0.4}{)} \times {10}^{{7}}$ S/m, respe- ctively. Electroless copper interconnections and LED circuit on glass substrate were fabricated as a proof of concept demonstrators.

Direct surface in-situ activation for electroless deposition of robust conductive copper patterns on polyimide film

Abstract In this work, selective surface activation by means of an alkaline reagent and silver-ion catalyst precursor is proposed for fabricating adhesion-enhanced and fatigue-resistant copper patterns on polyimide (PI) film through electroless deposition (ELD). Results from peel strength measurements and cyclical bending tests demonstrate that the deposited copper patterns are holding significantly enhanced adhesion strength over PI substrate. Meanwhile, a low resistivity of 2.82 × 10−6 Ω cm, i.e. 1.6 times of the value for the bulk copper is obtained by this approach combined with related parameters optimization. Analyses based on morphological and elemental characterizations indicate that the excellent conductive and mechanical features of the copper patterns are resulted from elevated crystallinity and highly densified metallic grains.