Bulk Copper Research Articles

ON-State Contact Resistance and Arc-Less Commutation Characteristics of Cu-W Clad Contact Materials in a Hybrid DC Switch

Hybrid dc switches have better performance with regard to energy conservation and less arc erosion than conventional semiconductor switches and mechanical switches. A novel hybrid dc switch based on a SiC-MOSFET is developed, and it accomplishes arc-less commutation if the current is below a threshold value, which is mainly determined by the boiling voltage of its contact material. However, as it is difficult for common contact materials to have both a low ON-state contact resistance and high boiling voltage, optimization of the contact materials is necessary to further decrease the ON-state contact resistance and improve the arc-less commutation characteristics of hybrid dc switches. New-type Cu-W clad contacts are proposed in this article by brazing tungsten top layers on copper bulks. The performance of the Cu-W clad contacts with the tungsten top layers of different thickness is evaluated by comparing their ON-state contact resistance and the threshold current of arc-less commutation with those of copper contacts and tungsten contacts under dc current ranging from 100 to 400 A. The results of the experiments show that the Cu-W clad contacts with the tungsten top layers of 1 mm thickness are the most suitable for arc-less hybrid dc switches because of their low ON-state contact resistance and largest threshold current of arc-less commutation.

Effect of copper oxide nanoparticles on two varieties of sweetpotato plants

Little information is available on the interaction of CuO nanoparticles (nCuO) with tuberous roots. In this study, Beauregard-14 (B-14, low lignin) and Covington (COV, high lignin) sweetpotato varieties were cultivated until maturity in soil amended with nCuO, bulk copper oxide (bCuO) and CuCl2 at 25–125 mg/kg. The Cu treatments had no significant influence on chlorophyll content. Gas exchange parameters were not affected in B-14. In COV, however, at 125 mg/kg treatments, bCuO reduced the intercellular CO2 (11%), while CuCl2 increased it by 7%, compared with control (p ≤ 0.035). At 25 mg/kg nCuO increased the length of COV roots (20.7 ± 2.0 cm vs. 14.6 ± 0.8 cm, p ≤ 0.05). In periderm of B-14, nCuO, at 125 mg/kg, increased Mg by 232%, while the equivalent concentration of CuCl2 reduced P by 410%, compared with control (p ≤ 0.05). The data suggest the potential application of nCuO as nanofertilizer for sweetpotato storage root production.

Broadband RF Characterization and Extraction of Material Properties in 3-D Printed Composite Substrates for Magnetically Tuned Circuits

3-D additive printing technology has been employed recently for the manufacturing of a wide variety of tunable radio frequency (RF) components. In particular, this article is focused on the extraction of magnetically tuned 3-D printed materials suitable for RF circuits. The design and modeling of tunable RF circuits require an accurate electromagnetic (EM) characterization of the 3-D printed dielectric [polylactide (PLA)] as a primary substrate, magnetic particles (CoFeO) as the tunable component in the composite substrate, and copper traces at RF frequencies. The extraction of complex permittivity, permeability, and conductivity parameters is reported over broadband (50–7000 MHz) and narrowband Wi-Fi bands (2.4 and 5.4 GHz) using the best fitting of EM simulated to measured scattering ( $S$ ) parameters. Broadband characterization is performed using best-fit modeling of three different physical lengths of microstrip transmission lines that are fabricated on unknown 3-D printed PLA substrates. Error analysis of this approach was evaluated on commercially available RT/Duroid substrate as a baseline. An accurate narrowband extraction procedure around the resonance frequency of 3-D printed annular ring resonators (ARRs) at 2.4 and 5.4 GHz is performed by the best fitting of simulated material RF properties to measured results. Further modeling improvements are presented through completely 3-D printed circuits that include the bottom and top copper traces with extracted conductivity of one tenth of bulk copper. Moreover, a 50-MHz tuning of ARR operating at Wi-Fi bands is observed and complex permeabilities are extracted at zero and 2-kG external magnetic field for the 3-D printed composite substrate.

Impact of enhanced interfacial strength on physical, mechanical and tribological properties of copper/reduced graphene oxide composites: Microstructural investigation

Copper/reduced graphene oxide (rGO) composites were prepared to improve the mechanical and tribological properties of copper without adversely affecting its physical properties in any significant manner. No hazardous chemicals were used for reduced graphene oxide production, which maintained the integrity of layers. For better dispersibility of rGO in the copper matrix, electroless deposition of copper was done on the activated and sensitized rGO surfaces. Different amounts of prepared Copper/rGO nanocomposites were then dispersed in bulk copper using ethanol and finally compacted using spark plasma sintering. The coefficient of friction of copper reinforced with 0.5 wt% of nanocomposite reduced by 77.5% compared to neat copper. The flexural strength of copper reinforced with 0.75 wt% of nanocomposite and modulus of 1 wt% of nanocomposite reinforced copper increased by 15.2% and 31.3%, respectively, with different strengthening mechanisms before and after yield point. The increase in hardness and strength of the material along with thin rGO films in the wear track accounted for the sharp decrease in the coefficient of friction for the composites. There was a minimal and gradual decrease in the physical properties (electrical and thermal conductivities) of the composites with an increase in the amount of reinforcement. The two-step composite fabrication process ensured better dispersion of rGO in the copper matrix, which resulted in even properties throughout the composite.

Solution Chemistry of Alkaline Formaldehyde-Containing Electroless Copper Plating Systems and Kinetics of Electroless Copper Deposition

Electroless copper plating process using solutions containing formaldehyde as reducing agent is known from the middle of this century and are widespread in the practice up to now. However, the investigation of this system remains actual because of its complexity, e. g. alkaline medium, hydrated form of formaldehyde (methanediol), Cu(II) complex compounds with different ligands, additives which improve the properties of the coatings obtained and/or protect from the reduction of copper(II) in the solution bulk. Moreover, various equilibria are possible including deprotonation of methanediol, Cu(II) complex formation, additional interactions between components of the solution.The aims and tasksof this work were to investigate or define more precisely equilibria in conventional alkaline solutions of electroless copper deposition as well as influence of the nature of Cu(II) ligands on the copper deposition process. This research report deals with the results obtained by means of dc-polarography, vis-spectrophotometry, voltammetry, potentiometry, pH-metry, 1H and 13C NMR spectroscopy, scanning electron microscopy, X-ray diffractometry and gravimetry.The composition, stability and the values of the diffusion coefficient of Cu(II) complex compounds with ligands (EDTA, DTPA, pyridine-2,6-dicarboxylic acid and 4-hydroxypyridine-2,6-dicarboxylic acid, Quadrol, L(+)-, D(–)- and DL(-/+)-tartrate, glycerol, saccharose and OH- ions) which are used or usable in alkaline electroless copper deposition solutions were established. Formation of mixed complex compounds between Cu(II) complexonates andK4Fe(CN)6, as well as between Cu(II) tartrate complexes and methanediol was investigated. The interaction of methanediol with L(+)-tartrate alongside with the influence of the ionic strength and cation nature on the deprotonation of methanediol in alkaline solutions were studied.The kinetic data on electroless copper deposition from solutions containing above-mentioned ligands are presented and the influence of the ligand nature on the process of electroless copper deposition is discussed.

Disrupting the Double Layer during Electrocatalysis By Applying a Pulsed Potential to Tune Product Selectivity for CO2 Reduction

The ability to control reaction kinetics and double layer species during an electrocatalytic process is highly desirable, especially for electrochemical CO2 reduction (CO2R) — a complex process in which multiple reaction steps are competing on the electrode surface. Here we show evidence suggesting the double layer can be disrupted with the application of a pulsed potential during CO2R.Pulsing the potential during CO2R using copper has been shown to influence product selectivity (i.e., to suppress the undesired hydrogen evolution reaction (HER)) and to improve electrocatalyst stability compared to constant applied potential.1 However, the underlying mechanism and contribution of interfacial/surface phenomena behind the pulsed potential application remain largely unknown. To uncover this unknown we investigated the state of the copper surface during the pulsed potential electrochemical CO2R using in-situ X-ray Adsorption Near Edge Spectroscopy (XANES). We probed the surface valence of the metallic electrode and found that the Cu electrode remains metallic over a broad pulsed potential range and only oxidizes to form Cu(OH)2 in the bulk when the pulsed potential reaches a highly oxidative limit (> 0.6 V vs. reversible hydrogen electrode (RHE)). Our results suggest that the pulsed anodic potential influences the double layer on the electrode surface, i.e., the dynamic competition between protons and hydroxide adsorbates instead of bulk copper oxidation. We attribute the suppressed HER to the electro-adsorption of hydroxides, which outcompetes protons for surface sites. As shown in a recent in-situ infrared study2, adsorbed hydroxides promote CO adsorption, a crucial CO2 reduction intermediate, by preventing CO from becoming inert through a near neighbor effect. We corroborate this interpretation by demonstrating that the pulsed potential application can suppress the HER during the CO reduction just as the CO2R. Our results suggest that the pulsed potential mechanism favors CO2R over the HER due to two effects: 1) proton desorption/displacement during the anodic potential and 2) the accumulation of OHads creating a higher surface-pH environment, promoting CO adsorption. We can describe this pulsed potential dynamic double layer mechanism in a competing quaternary Langmuir isotherm model.We conclude that the active disruption of the double layer can be leveraged to tune the surface reaction environment during CO2R. Furthermore, the insights from this investigation have wide-ranging implications for applying pulsed potential profiles to improve electrocatalytic processes in general by dynamically disrupting double layer species.[1] Kimura, K. W.; Fritz, K. E.; Kim, J.; Suntivich, J.; Abruña, H. D.; Hanrath, T. Controlled Selectivity of CO2 Reduction on Copper by Pulsing the Electrochemical Potential. ChemSusChem 2018, 11 (11), 1781–1786. https://doi.org/10.1002/cssc.201800318.[2] Iijima, G.; Inomata, T.; Yamaguchi, H.; Ito, M.; Masuda, H. Role of a Hydroxide Layer on Cu Electrodes in Electrochemical CO2 Reduction. ACS Catal. 2019, 9 (7), 6305–6319. https://doi.org/10.1021/acscatal.9b00896.

Microstructural and Textural Evolutions of OFHC Cu during the CECC Process and Annealing Treatment

The bulk Cu billets with ultrafine-grained microstructure were successfully processed from full-annealed coarse grained oxygen-free high conductivity (OFHC) Cu by the cyclic extrusion and closed compression (CECC), subsequently annealed at different temperatures. The evolution of the microstructure and mechanical properties was systematically studied. The results show that the effective strain per CECC process is ε=2.77, with further annealing treatment, a high-efficiency grain refinement is realized. After two cycles of CECC process and annealing at 350 °C for 1 h, the grain size refined to ～3 μm, the tensile strength increased to 280 MPa with a high ductility of 54%. Furthermore, a homogeneous structure and mechanical properties in the bulk copper billets for post-forging could be obtained.

Evaluation and mitigation of trace 210Pb contamination on copper surfaces

Clean materials are required to construct and operate many low-background physics experiments. High-purity copper has found broad use because of its physical properties and availability. In this paper, we describe methods to assay and mitigate 210Pb contamination on copper surfaces, such as from exposure to environmental radon or coming from bulk impurities. We evaluated the efficacy of wet etching on commercial samples and observed that 210Po contamination from the copper bulk does not readily pass into solution. During the etch, the polonium appears to trap at the copper–etchant boundary, such that it is effectively concentrated at the copper surface. We observed a different behavior for 210Pb; high-sensitivity measurements of the alpha emissivity versus time indicate the lowest level of 210Pb contamination ever reported for a commercial copper surface: 0±12nBq/cm2 (1σ). Additionally, we have demonstrated the effectiveness of mitigating trace 210Pb and 210Po surface backgrounds using custom, high-purity electroplating techniques. These approaches were evaluated utilizing assays performed with an XIA UltraLo-1800 alpha spectrometer.

Monte Carlo study on the temperature rise under electron irradiation

Scanning electron microscope (SEM) is frequently-used in analysis for micro/nanoscale structural information. During SEM analysis, besides the widely-known charging effect, the temperature rise because of electron beam bombardment also has become an issue due to it can modify SEM results with the downsizing of specimen, too. In this work, a sophisticated Monte Carlo (MC) model was adopted to quantitatively study the temperature rise during SEM imaging. The influences of various parameters on temperature profile for two different systems were examined: 1) semi-infinite metal copper (Cu) bulk focused on accelerating energy, incident electron beam angle (0° to 80°), incident beam size and the number of incident electron; 2) semi-infinite insulator Silicon dioxide (SiO2) bulk (amorphous SiO2) focused on scanning duration time. It was concluded that the temperature profile presents three characteristics: a) increasing first at surface until its maximum is reached, then has a sharp reduction as a function of depth from the surface for all two systems; b) being affected seriously by accelerating energy, incident electron beam angle and scanning duration time. The mechanism behind these phenomena was explained in detail. This work provides a better understanding and elucidation for physical mechanism of electron-beam-induced deposition, of which process control, performance and reliability would thus get a greater improvement based on this study.

Atomic Study on Copper–Copper Bonding Using Nanoparticles

Abstract Thermocompression bonding of copper to copper using copper nanoparticles is studied using molecular dynamics. The bonding interface formation process is investigated frst. For the bonding process, the effects of temperature and external pressure are examined. Also, we examine the grain growth at the interface. The results show that the nanoparticles with high surface energy and low compressive strength provide the active atoms to bond with copper. Pressure determining the degree of deformation of nanoparticles transfers atoms from the interior to the surface of nanoparticles and provide more surface atom to form bonds with bulk copper. While continuous pressure increase does not help bonding, higher temperature will facilitate formation of vacancies by breaking the bonds and driving the metal atoms into these vacancies. In addition, a higher temperature promotes grain growth at the interface. These behaviors indicate that using nanoparticles as a bonding layer in metal bonding can effectively reduce bonding temperature and pressure. It is necessary to select appropriate pressure at initial bonding stage and provide continuous high-temperature hold time.

Long-term assessment of nano and bulk copper compound exposure in sugarcane (Saccharum officinarum)

As interest in the use of copper-based nanomaterials in agriculture continue to increase, research into their exposure effects must expand from short-term, high exposure studies to long-term studies at realistic concentrations. Long-term studies can better elucidate the implications of copper nanomaterial exposure by allowing plants to mature and adapt to higher copper concentrations. In this study, sugarcane plants were grown to maturity in large nursery pots using soils amended with one of the following treatments: Kocide 3000 (Cu(OH)2), a nano-sized CuO (nCuO), a bulk-sized CuO (bCuO), copper metal nanoparticles (Cu NP), or CuCl2 at 20, 40, and 60 mg kg−1. After tissue harvesting, copper content in plant tissues, including pressed cane juice, were determined. Chlorophyll content and the activity of reactive oxygen species (ROS) related enzymes, in root tissues, were measured as an indicator of plant health. Elemental analysis revealed significant changes in root copper concentrations only upon application of the highest levels of Kocide 3000, nCuO, and Cu NP. However, translocation of copper to leaf tissues displayed consistent increases with added copper over controls. Plants treated with Kocide 3000 at 60 mg kg−1 experienced a significant 31% decrease in cane juice yield; copper concentrations in the pressed juice of plants treated with: Kocide 3000 at 20 and 60 mg kg−1, nCuO at 20 and 60 mg kg−1, bCuO at 20 mg kg−1, CuCl2 at 40 mg kg−1, and Cu NP increased by at least 58%. Chlorophyll content remained comparable to controls, and there was a significant 50 to 68% decrease in superoxide dismutase (SOD) activity in plants treated with nCuO, bCuO, Cu NP, and CuCl2. The results indicate that sugarcane plants exposed to the selected copper-based treatments were not adversely affected.

Additive Preparation of Conductive Circuit Based on Template Transfer Process Using a Reusable Photoresist.

To solve the problems of a conventional subtractive process for preparing conductive circuits, numerous alternative additive processes have been investigated, such as screen or inkjet printing, selective electroless plating, laser-induced forward transfer, etc. They all lead to a simpler procedure, less pollution, and finer line width but are still faced with difficulties like low conductivity and thickness, poor adhesion, and high cost. PDMS is a kind of material with low surface energy, leading to low adhesion with adhesive. Under these circumstances, a simple template transfer process for additively preparing conductive circuits is reported. The process to form the template includes the preparation of a photolithographic mask on the carrier copper foil and adsorption of PDMS anti-adhesion coating. Followed by metal deposition through electroplating on the template, the conductive circuits are transferred to the target substrate. Thus, the designed conductive circuits on various substrates including paper and cloth are formed. The template can be used again after being reimmersed into PDMS anti-adhesion coating. The components and the concentration of the coating are carefully discussed, and the mechanism of anti-adhesion is also researched by EIS and XPS. The copper circuits show a line width of 10 μm, a peeling strength of 7.11 N/cm, and a resistivity of 1.93 μΩ·cm, which is similar to that of bulk copper. With low pollution and cost, high versatility, and good electrical and adhesion performance, the template transfer process shows a good application prospect in the large-scale production of flexible electronics like sensors, RFID tags, etc.

Glycerol Conversion to Lactic Acid with Unsupported Copper Salts and Bulk Cupric Oxide in Aqueous Alkali Media.

Glycerol conversion to lactic acid (LA) was investigated in aqueous alkali over eight unsupported copper compounds (CuBr2, CuBr, CuCl2, CuCl, CuF2, Cu(NO3)2,CuO, and Cu2O) for studying the effects of anion and valence. Powder X-ray diffraction and scanning electron microscopy measurements indicated that these copper compounds were reduced to metallic copper with different morphologies. Divalent copper compounds exhibited much better performances than the corresponding univalent species, ascribed to their greater reduction heat and higher local reaction temperature. Divalent copper species activity, ionic radius, and the reported reduction potential decreased in the same order: bromide > chloride > floride ≫ nitrate. With increasing reaction temperature, catalyst amount, NaOH concentration and reaction time, glycerol conversion, and LA selectivity increased (due to by-product conversions to LA). Kinetic studies indicated that glycerol disappearance rate was first-order with respect to its concentration. CuBr2 had greater activation energy and therefore exhibited better performance than CuO when reaction temperature was greater than 155°C. At 185°C, CuBr2 reached 95.7% lactic acid yield and 98.65% glycerol conversion.

Comparative studies of helium behavior in copper and tungsten using molecular dynamics simulations

Helium (He) behavior in copper (Cu) and tungsten (W) bulk has been investigated and compared by molecular dynamics simulations. In contrast to the diffusion of He in W, interstitial He and He2 in Cu have higher diffusion coefficients and lower migration energies, which causes He atoms to rapidly coalesce into helium clusters. Once a Hen cluster (n ≥ 3) forms, trap mutation occurs in a short time. W atoms are less likely to be projected by Hen clusters. The binding energies are calculated to prove the results. For He2 in Cu, the dissociation of He2 and trap mutation both occur above 700 K. The total phenomenon exhibits Arrhenius behavior. The effective capture radii (ECRs) of an interstitial He trapping another one in Cu are obtained, which differ slightly from that in W. They decrease as the temperature increases, which deserves more attention, as the ECRs are required in MC and RT models.

Experimental Research on Electromechanical Properties of Multiple Contact Surfaces Copper Bulks under Normal Cyclic Loading and Variable Temperature.

Contact resistance is key for stable operation of electrical contact equipment, and can also be extensively applied. For Tokomak devices in fusion reactors, contact resistance of the superconductor magnet system strongly relates to the alternating current (AC) loss of the cable; the cable is assembled using a certain number of contacting superconducting tapes coated with copper layers on both sides. The contact resistance of a metal solid surface is affected by many factors. In this work, the contact resistance of copper surface samples was studied experimentally under variable normal cyclic load, temperature and number of contact surfaces. This is consistent with real-world working conditions, as the structure of superconducting cables can be changed, and such cables are used under cyclic electromagnetic forces in temperatures which range from room to working temperature. Experimental results showed that contact resistance decreased rapidly with an increase of load. Further, when temperature was varied from 77 to 373 K, the load–unload contact resistance lag decreased. When the number of contact surfaces was increased, contact resistance increased. Finally, a fitted formula describing the relationship between contact resistance and cyclic times, temperature and number of contact interfaces was determined. This formula can be used to predict variation trends of contact resistance in complex environments and provide more accurate contact resistance parameters for calculating the AC loss of superconducting cables.

Copper‐Leaf‐Based Process for Imperceptible Computational Electronics

AbstractImperceptible electronics have a key role in tomorrow's wearable technologies. Individual elements such as ultra‐thin sensors, batteries, solar cells, and actuators are well described in literature, but there is a lack of methods to build the computing circuit itself. A new process is presented for the fabrication of flexible and imperceptible circuits that reach standards of microelectronics associated with significant integration density of components and interconnections, as well as multilayering. The stack uses a commercialized decorative copper leaf with a thickness of 450 nm as the conductive layer and a parylene substrate of a few micrometers. The copper leaf shows both high compliance and conductivity of bulk copper (5.96 × 107 S m−1), with electrical resistance stable over 5000 cycles of complete folding. The process requires stencil‐free laser patterning that reaches fine‐pitch integration, conventional soldering methods, and a three‐step via fabrication and assembly process for multilayered circuits. The functionality of an ultra‐thin, multilayered, lightweight, electrocardiogram‐monitoring device is demonstrated. This allows for direct transfer of microelectronic designs for rapid prototyping from rigid board to imperceptible electronics.

The Anodic Behaviour of Bulk Copper in Ethaline and 1-Butyl-3-Methylimidazolium Chloride

The anodic dissolution of bulk metallic copper was conducted in ionic liquids (ILs)—a deep eutectic solvent (DES) ((CH3)3NC2H4OH) comprised of a 1:2 molar ratio mixture of choline chloride Cl (ChCl), and ethylene glycol (EG)—and imidazolium-based ILs, such as C4mimCl, using electrochemical techniques, such as cyclic voltammetry, anodic linear sweep voltammetry, and chronopotentiometry.To investigate the electrochemical dissolution mechanism, electrochemical impedance spectroscopy (EIS) was used. In addition to spectroscopic techniques, for instance, UV-visible spectroscopy, microscopic techniques, such as atomic force microscopy (AFM), were used. The significant industrial importance of metallic copper has motivated several research groups to deal with such an invaluable metal. It was confirmed that the speciation of dissolved copper from the bulk phase at the interface region is [CuCl3]− and [CuCl4]2− in such chloride-rich media, and the EG determine the structure of the interfacial region in the electrochemical dissolution process. A super-saturated solution was produced at the electrode/solution interface and CuCl2 was deposited on the metal surface.

Conductive films prepared from inks based on copper nanoparticles synthesized by transferred arc discharge

Copper nanoparticles (NPs) are considered as a promising alternative for silver and gold NPs in conductive inks for the application of printing electronics, since copper shows a high electrical conductivity but is significantly cheaper than silver and gold. In this study, copper NPs were synthesized in the gas phase by transferred arc discharge, which has demonstrated scale-up potential. Depending on the production parameters, copper NPs can be continuously synthesized at a production rate of 1.2–5.5 g h−1, while their Brunauer–Emmett–Teller sizes were maintained below 100 nm. To investigate the suitability in electronic printing, we use ball milling technique to produce copper conductive inks. The effect of ball milling parameters on ink stability was discussed. In addition, the electrical resistivity of copper films sintered at 300 °C in reducing atmosphere was measured to be 5.4 ± 0.6 μΩ cm which is about three times higher than that of bulk copper (1.7 μΩ cm). This indicates that conductive inks prepared from gas-phase synthesized copper NPs are competitive to the conductive inks prepared from chemically synthesized copper NPs.

Microembossed copper microchannel heat sink for high‐density cooling in electronics

A microembossed copper microchannel heat sink was designed and fabricated for high-density cooling in electronics. The microchannel width and aspect ratio were investigated to find out the optimised channel size for microembossing. The fabrication method was based on bulk copper forming including tungsten die inductively coupled plasma etching, hot copper microembossing, inlet/outlet ports punching and sealing. The heat dissipation performances were tested by ceramic heater. The maximum temperature decreased to ∼37°C under different heat fluxes, with the maximum temperature decreased by 69.2% at 50 W/cm2 heat flux. The equivalent heat transfer coefficient reached the value of 6492 W/m2 K. High-power chip was used as heat source too. The maximum heat flux reached 304.8 W/cm2 when the chip can still function properly at 90.5°C. High cooling performance with the micro-heat sink proves that microembossing by tungsten die is an alternative process for microchannel heat sink fabrication with batch production and low cost. Taking advantages of simple fabrication process and reutilisation of tungsten die, the technology shows promising potentials in high-density microcooling systems.

Improvement of Copper–Graphene Composites Properties due to the Lubricating Effect of Graphene in the Powder Metallurgy Fabrication Process

Bulk copper–graphene composites are regarded as novel materials for the application for electronics. However, the properties of the composites and their microstructure are highly dependent on synthesis technique parameters as well as the graphene additive contents and its type: graphene flakes, graphene nanoparticles, reduced graphene oxide particles, etc. In the present work, powder metallurgy technique was modified to produce copper–graphene composites; the milling procedure was optimized basing on particle size distribution data. The optimal amount of graphene additive to copper powder was calculated via the simple mathematical model, where metal–graphene composite is regarded as a core–shell particle. That approach was used to produce copper–graphene composites with the graphene contents of 0.1, 0.5, and 1.0 wt%. In case of 3 wt% of carbon additive (thermally exfoliated graphite) copper-graphite–graphene composites were obtained. The microstructure of samples was studied by scanning electron microscopy and electron back-scattering diffraction. The identification of carbon allotropes was performed by Raman spectroscopy. It was shown that the graphene additive acts as a lubricant during powder metallurgy process: carbon allotrope flakes are not introduced into the material matrix but extruded to pores. As a result, a new synthesis approach for copper–graphene composites manufacturing with improved microstructure and mechanical properties was suggested.