Papers by Keyword: Copper Foil

Abstract: This study deals with the influence of thickness of copper foil on its tensile property. Tensile tests were carried out on copper foils with various thickness ranging from 5 μm to 2 mm in air. Then, the tests on copper foil with the thickness of 20 μm and copper sheet with the thickness of 2 mm were also conducted in a scanning electron microscope, and their deformation was examined during testing using an electron backscattered diffraction method. The influences of thickness of copper foil on its deformation, tensile strength, and fracture morphology were investigated. As a result, the tensile properties of copper foil depend on its thickness, and the tensile strength decreased when the foil thickness was thinner than the grain diameter.

Abstract: Copper foils with 91% cold rolled deformation annealed at temperature between 140°C and 170 °C.The microstructures were observed by EBSD. The mechanical properties were measured at room temperature by tensile test machine and the fracture morphologies observed by SEM. After annealed at 150 °C, recrystallization begins to occur, while the elongation increases evidently and tensile strength decreases sharply. When the temperature rises to 170 °C, recrystallization is complete and the grain starts to grow. When the foils are annealed at 140 °C, it exhibits a strong cold rolling textures characterized by Brass {011}<211> and Cu {112}<111>. After annealed at 170 °C, there are olny weak Brass {011}<211> texture.

Abstract: Surface treated copper foil and its preparation is very important and widely used. The science research and enterprise competition always focus on the surface treated methods in the copper foil field. This paper summarized the typical surface treated processes of copper foil, and emphasized on research progress and problems of copper foil surface treated processes. The brush plating-dealloying treated process of copper foil was proposed based on the problems. The principle and research status of new process was introduced. At last, the future development of surface treated process and application prospect were forecast.

Abstract: The occurrence of size effects in the microforming leads to the uncertainties in process determination and quality control. In this research, a series of experiments were conducted in UTM4104 testing machine to investigate the grain size effect and feature size effect in micro-bending. Different grain size (d), thickness to grain size ratio () and micro-mold feature size (W) were prepared to explore size effects on formability of copper foil. The formability characterized by forming depth, deformation uniformity and surface integrity was discussed. It was found that the normalized forming depth presented a gradually rise and then declined markedly when N value further decreased to 0.79. The ductile fracture mode was observed for all grain-sized workpiece and the corresponding limit forming depth decreased with increasing grain size. Besides, the thickness thinning distribution and microhardness distribution showed the similar variation tendency like M. Both the standard deviation of thickness reduction and the roughed degree of surface topography indicated the worsening deformation uniformity of the foils with a larger grain size. The inhomogeneous plastic flow of material may be the reason to explain the depression near fracture location which is only observed in coarse-grained workpiece. Overall, it is concluded that the fine-grained copper exhibited better formability as the coarse-grained workpiece experienced severe strain incompatibility.

Abstract: A pre-cleaning and an electroless nickel plating (EN-HP) were applied to copper foil to improve its tribological behaviour and corrosion resistance. The coating porosity was measured by the corrodkote, tribological behaviour was measured with microhardness tester and a CSM ball-on-disk tribometer, corrosion resistance was measured by potentiodynamic polarization in 3.5 wt.% NaCl solution. Matte nickel plating (mNi) and moderate compact Ni–P coating (EN-MP) were made as comparisons to EN-HP in those tests. By deposition of EN-HP, both coating porosity and tribological behaviour are greatly improved compared to mNi, and the corrosion resistance is distinctly ameliorated to the comparisons. Above research demonstrates that the copper foil with EN-HP coating is good underlay in assemblage of machine.

Abstract: This study investigated the classification error rate of eleven flaws commonly occurred in copper foil. The goal was to online identify the type of the flaw being discovered in order to trace the source of the flaw and act correspondingly. The misclassification rates of four popular classifiers were investigated and compared. The results indicated that the best classification rate can be obtained by choosing Support Vector Machines as the classifier and employing all the ten features. The resulting low classification error rate of 4.41% proved the effectiveness of the derived classifier as well as the suitability of the chosen features.

Abstract: Superhydrophobic surface was prepared by hydrothermal method on copper substrate via immersing the clean pure copper substrate into the mixed solution of H₂O₂ and C₂H₅OH, and then the substrate was heated at 100°C for 1.5 h, followed by modifying with stearic acid. The product was characterized by scanning electron microscopy and X-ray photoelectron spectroscopy. The wettability of the products was also investigated. It was found that the as-prepared surface had a high water contact angle of about 153°. SEM images of the film showed that many irregular micro-nano sheets distributed on the surface in a random pattern. The special porous architecture, with the low surface energy leads to the surface superhydrophobicity.

Abstract: The ageing of copper foils and Copper foils-surfaced in UV rays are studied by 3D Video, SEM, EDX, which shows that copper foils and Copper foils-surfaced are in different level of ageing; embossment and crack which are the most obvious aging characteristics found by SEM, obviously, the ageing velocity of copper foil -surfaced is higher; The sulfur is found in the powder-like material around the embossment on the surface of copper foils by EDX, which indicates that sulfur is involved in the process of aging.

Abstract: Foil bearing that has a soft surface is a kind of air bearing. The performances of foil bearings are greatly affected by the materials of bearing surface, which is called foil element. In order to estimate the performance of foil bearings, two kinds of foil thrust bearings that are made of different materials respectively were tested in a micro turbine system, which contains rotation part and static part. Load capacity and stability of these foil thrust bearings were investigated in experiments. The results show that bearing which contains rubber has higher load capacity and bearing which contains copper foil has higher stability. According to the work in this paper, applications with different requirements can adopt suitable foil thrust bearing.

Abstract: The effectiveness of residual stress on forming copper patterns of printed circuit board was investigated during applied thermal conditions. Generally, the electrolytic copper foil showed a compressive residual stress about -54MPa as received, which easily caused to form copper patterns irregularly. We verified the compressive residual stress was relaxed with applying thermal conditions under 200°C for a few hours. And also, we observed that the compressive residual stress of copper foil tended to be relaxed, constant, and compressive again during heating times at each temperature. The relationships between residual stress and etching factor of copper pattern were analyzed in this works.