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Copper foils demonstrate a tendency for self-annealing, which adversely impacts the stability of the products. The self-annealing induced recrystallization of copper foil is closely related to the grain growth mode. When copper foil grows in equiaxed grain mode, resulting in a decrease in tensile strength from 780 MPa to 330 MPa. Conversely, the columnar grain copper foil exhibits excellent room-temperature stability in mechanical properties. The mechanism of copper foil room temperature self-annealing behavior was put forward. It was found that the internal stress generated in the process of preparing copper foils is the key factor driving the recrystallization of equiaxed grains. This internal stress originates from nanocrystals and high-density dislocations, with the latter arising from the doping of organic elements. The initial high stress values and the plasticity of dislocations contributed to a noteworthy decrease in residual stress. As dislocation plasticity ensues, the anchoring of interstitial atoms gives rise to dislocation loops. The interaction between dislocation loops and coincident twin boundaries induces the formation of twin steps. The quantity of twins of equiaxed copper foil increases greatly after self-annealing. Conversely, the initial dislocation density of columnar grain copper foil is an order of magnitude lower than that of equiaxed grains.

In this work, the formability of copper foils was analyzed based on a series of multi-step micro deep drawing (MMDD) tests. The copper foils were annealed at temperatures ranging from 300 to 700 °C for 5 min, followed by tensile tests and electron backscatter diffraction (EBSD) tests for the exploration of mechanical behavior and microstructural characterization of annealed specimens. The results show that the as-received copper foils exhibit poor formability and cannot form micro cups during MMDD. When the annealing temperature attains 500 °C, a homogeneous microstructure was formed inside copper foils, enhancing the formability of materials and improving the surface quality of formed products. Nevertheless, both the elongation and tensile strength decrease dramatically due to the easy occurrence of incoordination deformation in coarse grain bands with further increase in annealing temperature to 700 °C. Consequently, marked wrinkling is generated on the surface of drawn cups and obvious thinning occurs at the nose radius region due to metal flow. In addition, the results show that the E texture component within the copper foils is favorable for MMDD. Overall, an optimal annealing temperature of 500 °C is obtained with improved formability of copper foils and forming quality of drawn cups.

Accurately calculating winding losses has always been a significant challenge in the design of large-capacity medium-frequency transformers. This paper presents an accurate design algorithm for calculating the winding losses of a large-capacity medium-frequency distribution transformer. First, the peculiarities of winding losses in medium-frequency distribution transformers are analyzed. Various commonly used winding conductor types for medium-frequency transformers are introduced. The mechanisms of and differences between AC and DC winding losses in medium-frequency transformers are explained, and an effective analytical method for calculating the AC-to-DC resistance ratio is provided. Finally, the analytical calculation results of different types of winding losses are compared with those obtained through finite element simulations and experimental methods applied to a real transformer prototype. The discrepancies between the analytical results and those obtained using the other two methods were found to be within acceptable error margins, thereby validating the accuracy and effectiveness of the proposed algorithm.

Electrodeposition technology is widely used in the surface treatment of copper foil. The unique “mechanical disturbance effect” and “cavitation effect” of ultrasonic field can effectively control the electrodeposition process of Cu and improve the quality of electrodeposited layer. In this paper, Linear Sweep Voltammetry (LSV), Cyclic Voltammetry (CV), Chronoamperometry (CA) and Chronocoulometry (CC) were used to study the electrochemical behavior of electrodeposited Cu in ultra-high acidity sulfate systems under different ultrasonic field powers. The nucleation and growth mechanism of Cu were discussed, and the surface morphology of electrodeposited layer was analyzed. The results show that the electrodeposition of Cu under the static condition (0 W) follows the diffusion controlled progressive nucleation and 3D growth mechanism, and the deposits are in the cylindrical shape with spherically agglomerated. The ultrasonic field significantly improves the mass transfer rate in the electrodeposition process, and the fine dispersion effect is obvious. The uniform and dense micro-nano layers are formed, following the 3D growth mechanism. With the increasing of ultrasonic field power, the nucleation mechanism gradually changes from the diffusion controlled progressive nucleation to the electrochemistry controlled instantaneous nucleation. In addition, there appear peeling, grooving and local microcracks on the electrodeposited layer under higher ultrasonic power condition, and it is easier to form a smooth and uniform electrodeposited layer with the ultrasonic power of 60 W compared to that with the ultrasonic power of 100 W.

Advanced thermal interface materials with high thermal conductivity are crucial for addressing the heat dissipation issue in high-power, highly integrated electronic devices. One great potential way in this field is to take advantage of cooling copper foil (Cu) materials based on graphene (G). However, the current manufacturing of these cooling copper foil materials is accompanied by high cost, process complexity, and environmental problems, which limit their development and application. In this work, a simple, low-cost, environmentally friendly graphene-copper foil composite film (rGO/G-Cu) with high thermal conductivity was successfully prepared using graphene oxide directly as a dispersant and binder of graphene coating. The microstructure characterization, thermal conductivity and thermal management performance tests were carried out on the composite films. The results demonstrate that compared to pure copper foil (342.47 W·m−1·K−1) and 10% PVA/G-Cu (367.98 W·m−1·K−1) with polyvinyl alcohol as a binder, 10% rGO/G-Cu exhibits better thermal conductivity (414.56 W·m−1·K−1). The introduction of two-dimensional graphene oxide effectively enhances the adhesion between the coating and the copper foil while greatly improving its thermal conductivity. Furthermore, experimental results indicate that rGO/G-Cu exhibits excellent heat transfer performance and flexibility. This work is highly relevant to the development of economical and environmentally friendly materials with high thermal conductivity to meet the increasing demand for heat dissipation.

Hydroxyethyl cellulose (HEC) has been commonly used in a variety of complex formulations for acid copper plating. However, the roles of HEC acting in acid copper plating still lacks of systematic investigation. To explore the efficacy of HEC in the deposition of the ultra-thin electrodeposited copper foil (ED-Cu), we designed a simple formulation system, in which HEC was used as the single organic additive. Using electron backscatter diffraction (EBSD), microstructures of the prepared ED-Cu was comprehensively investigated. The results showed that the ED-Cu was characterized by a mixed distribution of columnar and equiaxed crystals. Grain morphology, dislocation density and crystal orientation of the ED-Cu could be regulated by HEC concentration. According to the cyclic voltammetry (CV) and chronoamperometry (CA) results, the introduction of HEC between 0–200 ppm led to a polarizing effect, which marginally increased with the HEC concentration. Meanwhile, the increase of HEC concentration enhanced the nucleation rates of copper and reduced the grain size during instantaneous nucleation. The introduction of the HEC also altered the preferred orientation of the ED-Cu foil. Mechanical results showed that the optimum concentration of HEC addition was 125 mg l ^−1 .

Batteries are a very efficient energy source used in an all-digital environment that adapts to today’s human mobility. The lithium-ion battery is one of the batteries used in various household appliances. There are some problems caused by the anode in terms of utility. This is due to high electrochemical reactivity, which can reduce battery performance. One of the innovations in lithium-ion batteries is anode-free Li-ion battery (AFLB). The working mechanism of this battery is the same as the previous Li-ion battery, but with a smaller anode capacity, so that it can reduce the volume (large) of the battery. The problem that arises is the growth of dendrites that interferes with the battery’s running mechanism, so it needs to be evaluated for its growth. The way that can be done is to modify the copper foil by adding Cu. The innovation of this research is to modify Cu-foil by adding Cu from cable waste. The research method used is leaching Cu from cable waste, followed by reducing Cu powder to form a modified Cu. This study’s data collection techniques include empirical research derived from previous studies and instrumental analysis using SEM, FTIR, and electrochemical performance tests. Electrochemical testing using a cylindrical battery with a current of 1 C (1 C = 430 mA g−1) and a voltage of 2.6–4.3 V obtained ALFB and ALFB Cu-modification batteries with a discharge capacity of 70 and 123 mA h g−1, respectively.

Hexagonal, carbon-based structures were prepared on bare and treated copper foil substrates by Chemical Vapor Deposition at 1075 ᵒC using a graphite box for limiting copper reactivity with hydrocarbon gases during growth reactions. Spectroscopic ellipsometry with a digital camera was used to collect the amplitude ratio and the phase of structures various spots. The amplitude ratio of hexagonal structures on copper substrates was collected based on substrate treatment type and thickness as well as reaction zone conditions and methane flow rates. Matched amplitude ratio was obtained only for 75 µm thick acetic acid copper foil substrates inside and outside the graphite box at a low methane flow rate of 0.2 sccm. Moreover, the amplitude ratio of 75 µm bare copper foil and 75 µm electro-polished copper foil substrates at methane flow rates of 0.2 - 0.3 sccm were unmatched. Ellipsometric parameters data use potential is assessment of graphene layer thickness on different surfaces. Data shows dependence of the amplitude ratio on the surface roughness of copper foil, gas concentrations and reaction zone conditions.

Chemical vapor deposition is the most promising approach for synthesis of large-area monolayer graphene on Cu foil. However, numerous factors can result in formation of adlayers, such as the morphology of the Cu foil, methane concentration, and growth temperature. Here, we report atmospheric pressure chemical vapor deposition growth of large-area adlayer-free monolayer graphene by the two-step ‘bottom-up-etching’ method. The experimental results showed that a temperature increase in the second step can dramatically accelerate etching of the bottom graphene layer. A growth model for adlayer-free monolayer graphene on Cu foil is proposed.

Sheet metal bending is defined as a straining process of flat strip material around a linear axis. The micro V-bending process was conducted to investigate its punch force behavior with 0.1 mm thick copper foil. The V-shaped configuration of the punch and die provides a simplicity of tools and an ability to produce different bending angles with a single tool. During the straining of material, a unique force profile, which is related to punch trajectory, occurs. The process was performed with the punch speeds 0.5 mm/s, 1.0 mm/s, 5.0 mm/s and 10.0 mm/s. The results showed that the punch force profile consists of the free-bending stage and the coin-bending stage. In the free-bending stage, the force magnitude was not influenced by the punch speed for the same geometrical and mechanical properties of the sheet material. Furthermore, during the coin-bending stage, the force magnitude increased significantly since the material needed to be bottomed.

In this paper, the effect of grain size and micromorphology of Cu foil on the velocity of the flyer of an exploding foil detonator was studied. A Cu foil with different grain sizes and micromorphologies was prepared by the physical vapor deposition sputtering method. The flyer velocity of the Cu foil was measured by the photon Doppler technique (PDT). The influence of the grain size and micromorphology of the Cu foil (which was the core transducer of the exploding foil detonator) on the flyer velocity and reacted morphology was discussed. The results show that the grain size and micromorphology of the Cu film can greatly affect the velocity and morphology of the flyer. The grain size of the Cu film is more uniform, and the stimulus response in the middle area of the bridge foil is more concentrated. In addition, the current density becomes more uniform, resulting in a better explosion performance. Consequently, the speed of the formed flyer becomes higher, leading to a smoother flyer surface, which is more conductive to energy conversion.