Copper Terminals Research Articles

Microscopic mechanism of ultrasonically welded joints: The role of terminal roughness and wire diameter

The ultrasonic welding technology is widely promoted as a new connection approach in the field of current energy vehicle wiring harness connection. In this paper, three kinds of 25mm2 copper wire harnesses with different wire diameters and T2 copper terminals with different surface roughness were welded by ultrasonic welding. The mechanical properties of the joints were investigated by tensile experiments and the microstructure of joints was characterised using SEM and EBSD techniques. Excessive roughness increases plastic deformation at the weld interface during ultrasonic welding. This increases the dislocation density at the weld interface and refines the grain size. However, at the same time it inhibits recrystallisation to a certain extent. The lower roughness facilitates recrystallisation, but the low density of HAGBs makes the interface susceptible to slip in extended crystallographic plane and direction. Appropriate roughness allows the weld interface to generate fine equiaxed grains and a high density of HAGBs. This facilitates the obstruction of dislocation movement and improves the strength of joint. In addition, the high porosity of a longitudinal cross-section of the conductor with its small diameter was investigated. This results in a large number of wires remaining on the terminals when force is applied. It was determined that the larger a diameter of wire, the higher a cross-sectional porosity. The copper wire breaks at a weak point in cross-section when the force is applied, resulting in the entire wire being left on terminal. At a wire diameter of 0.2 mm, the porosity of a cross-section reaches an equilibrium and the strength of joint is even higher than the strength of material itself, resulting in the joint pulling off. The maximum strength reaches 4703.77 N.

Formation mechanisms and mechanical properties in aluminum cables and copper terminals ultrasonic welded joint

To fabricate highly reliable Al cables/Cu terminals components and elucidate the microstructure evolution of the joint during ultrasonic welding, ultrasonically welded structures of 50 mm2 Al cables and 2 mm-thick copper terminals were conducted at welding energies from 1200 J to 2800 J and an amplitude of 54.6 μm in this paper. As the welding energy increased, the degree of plastic deformation of the Al wires gradually increased, the microstructure of the Cu side remained basically unchanged, and the effective contact area of the Cu/Al interface was gradually enlarged, enhancing the coherence between the Al wires, and the Cu-Al interfacial structure changed from an unbonded area to continuous mechanical interlocking. Parallelly, the Al grains transformed from fine serrated to equiaxed and lamellar crystals driven by geometric dynamic recrystallization (GDRX), continuous dynamic recrystallization (CDRX), and dynamic recovery (DRV), forming distinct shear textures of B/B̅{111}<110>, Rt Goss{110}<110>, Rt Cube{001}<110> and the recrystallization texture F{111}<112>, and the content of shear textures increased from 2.9% to 17.4%. In addition, the tensile shear failure load of the joint reached 2962 N, which met the requirements of cable installations in the field of new energy vehicles (>1650 N). Fracture analysis showed the fracture location transitioned from the Cu-Al interface to the Al-Al interface with an increase in welding energy from 1600 to 2400 J. This work has theoretical guidance for the continuous promotion of vehicle light-weighting.

Ground Based Recharging System for Electric Buses

In response to the growing demand for efficient and convenient electric vehicle (EV) charging solutions, this paper proposes a novel ground-based charging system tailored for EV buses and trucks. The system utilizes a current collector mechanism akin to pantograph charging, integrating a linear actuator with three terminals for positive, negative, and ground connections. Pogo pins, each rated at 5 amps and connected in series, are employed as connectors for reliable power transfer. The ground infrastructure consists of buried copper terminals arranged in a grid formation, covered with a silicon inductor sheet to ensure safety and durability. Upon the arrival of an EV bus/truck, a proximity sensor detects its position, prompting the driver to initiate the charging process by scanning a QR code and entering identifying information via IoT communication. Activation of the linear actuator, controlled through a relay system, establishes the power connection between the vehicle and the ground-based infrastructure. Upon completion of charging, the system is deactivated, and the vehicle can resume its journey. This paper outlines the design, operation, and potential benefits of the proposed ground-based charging system, offering a promising solution to enhance the efficiency and accessibility of EV charging for public transportation fleets.

Radial plastic flow machining: A new process for fabricating gradient-structured terminals in one step

Radial Plastic Flow Machining (RPFM) is a novel severe plastic deformation process. By designing a specific plastic flow channel, the material is allowed to flow radially into the predetermined channel under the combined action of extrusion and cutting. A restricting ring is placed in the channel to form a copper terminal structure in one step. This study investigates in detail the formation mechanism, mechanical properties, and thermal stability of gradient structured copper terminals generated under different extrusion angles. It was found that as the extrusion angle increased, the high strain region slightly decreased, while the low strain region increased, allowing more material to be radially extruded. This indicates that tensile strength and toughness can be balanced by controlling different extrusion angle parameters. In performance testing, the study showed that the hardness of the copper terminals prepared by RPFM was more than double that of the original copper material, and the maximum tensile strength also doubled. Moreover, the performance of the copper terminals annealed at 150∘C was similar to that of untreated copper terminals, demonstrating good thermal stability at this temperature. The study suggests that RPFM is not only an effective process for manufacturing gradient structured copper terminals in one step, but it also provides a new method for manufacturing copper terminals with excellent comprehensive performance.

THE DESIGN OF THE POWER SUPPLY CURRENT LEADS TO A HIGH-TEMPERATURE SUPERCONDUCTING ELECTROMAGNET

The paper presents a theoretical and experimental analysis of thermal conditions imposed on the power supply conductor for an HTS YBCO-type high magnetic field electromagnet. For thermal stability during the operation of the electromagnet, it is essential to lower the heat flux from outside the system. The heat from the surrounding environment to the HTS winding is limited by using an adequately sized cryogenic system and the proper design of the current leads. The HTS winding and current leads are cooled with a two-stage GM cryocooler. If the power supply conductor's conductive heat flux exceeds the cryocooler’s heat load, the temperature of the HTS winding will increase, and system instability may occur. The power supply conductors are of two types: copper conductors and mixed HTS conductors. This work analyzes HTS conductors and junctions of HTS tape with copper terminals and their contribution to the cryocooler’s total heat load. Using HTS conductors reduces Joule heat when current passes through them (approx. 300 A) and the conductive heat flux to the HTS windings. Resistance for various soldering alloys was experimentally evaluated to evaluate the Joule heat of the junctions between HTS conductors and copper terminals.

Selection of Magnetic Pulse Crimping Process Conditions to Improve Crimped Terminal Quality

The crimping of copper terminals via hand-operated and hydraulic compressors is used to generate a compressive force between a terminal and a wire, generally on a worksite. However, this equipment often causes compression defects because non-uniform pressure is applied to the terminal surface in the radial direction during crimping. When the crimped terminal is connected to electrical parts such as the power transmission system, a low-quality crimped terminal can separate from the wire strands, increasing resistance to current flow through the terminal, energy loss, and the risk of fire due to overheating. For this reason, Magnetic Pulse Crimping (MPC), which can yield highly durable crimped terminals with uniform quality, has recently been developed. This process uses only the magnetic force generated by high electromagnetic interaction between the crimping coil part and the surface of the terminal, without physical contact. The objective of this research was to confirm the superiority of the MPC process over the conventional crimping process and then analyze the effects of the main process parameters, including the crimping length and the charge energy on the crimping part, so that this new process can be applied at worksites. To realize these goals, copper terminals and 35 mm2 copper wire strands were employed, and various types of crimping parts were manufactured under different crimping conditions. In particular, the distribution of electromagnetic force on the crimped parts were analyzed via numerical analysis. The crimping part performance was improved when the MPC process was applied to terminal crimping. In particular, decreasing the crimping length led to increased crimping quality, while increasing the charge energy caused increases in the compression ratio and pullout strength. However, excessively high charge energy caused the edge to break the wire strands; therefore, it is important to select the proper charge energy.

Design Water Turbine as Pump Drive for Irrigating Paddy Fields in the Highlands in the Panjalu Ciamis Region

In electrical systems, safety is the main factor, but it is often overlooked because it is quite expensive. The current conventional outlet, although it has been standardized by the Indonesian national standard, is a fact in the field that there are still many incidents of electric shock, because the voltage continues to flow through the copper terminals inside the plastic frame protector. This incident can occur because the terminal is plugged into a conducting object such as a fork, spoon, iron rod, or held directly with a finger. For this reason, in this study, a safety system is made that uses the main component of the Relay as an intermediary for DC voltage and AC voltage. Trials carried out 50 times on each socket box resulted in solving the problem by conditioning the plug that had not been plugged into the terminal so that there was no voltage flowing into the outlet, this certainly distinguishes safety from using an ELCB which must have contact with the human body first.

Influence of different surface conditions on mechanical properties during ultrasonic welding of aluminum wire strands and copper terminals

Ultrasonic metal welding (USMW) has become considerable attention in terms of its suitable applications compared to conventional fusion welding techniques. The main advantage of USMW results from the comparatively low process times and joining temperatures below the melting point. Thus, USMW is particularly used for the joining of dissimilar material combinations, e.g., aluminum and copper (Al/Cu), in battery cell production or wiring harness applications. However, process fluctuations in USMW of Al/Cu joints can occur due to varying surface conditions of the joining materials. Therefore, this study investigated different surface conditions of copper terminals and their effects on mechanical properties. At first, three different surface conditions were generated, respectively: surface cleaning (sulfuric acid and ethanol), structuring process by laser, and structuring process by milling. These modifications are compared with the terminals in the initial state (contaminated). The characterization of the terminal surfaces was carried out with 3-D laser scanning microscopy as well as light microscopy. The mechanical conditions were examined with shear tensile tests. The tensile tests showed a significant influence of the surface condition on the resulting failure loads compared to the initial state. The highest failure loads could be achieved with the structured terminals (+ 48%), whereas contaminated terminals and terminals with notches exhibited comparatively poor failure loads (− 28%). This can be explained by varying interface formations between the terminal and the wire, which was detected by metallography and SEM analysis. Furthermore, it was figured out that the interface between aluminum and copper exhibits a firm and formed closure bond and hence increased failure loads for laser-structured terminals. Additional investigations by SEM revealed no detectable occurrence of intermetallic phases.

Joints formation and bonding mechanism of ultrasonic welded multi-strand single core copper cables with copper terminals

• Metallurgical bonding of multi-strand single core copper cables with copper terminals was achieved by ultrasonic welding technology. • Formation of bonding interfaces involved plastic deformation, dynamic recrystallization, and dynamic recovery. • Fine equiaxed grains at the bonding interfaces were beneficial to increase the strength of the joints. The metallurgical bonding of multi-strand single core copper cables with copper terminals was achieved by ultrasonic welding technology. The joint forming process and bonding mechanism that involved plastic deformation, dynamic recrystallization and dynamic recovery were clarified. The necklace-like fine grains structures observed in the central areas of the bonding interfaces would significantly improve the T -peel strength of the joints.

Development and Engineering Application of the Measurement System Based on the Miniaturized Ultrasonic Transducer

The iron terminals are mostly used in the small ultrasonic transducers which are connected to the circuit board by the direct or indirect welding method. Although the method is considered to be firm and reliable, the ultrasonic transducer or the whole system is easy to be damaged when the ultrasonic transducer is replaced or maintained. Moreover, the terminals of the ultrasonic transducer are easy to be oxidized. The miniaturized ultrasonic transducer with the electroplated copper terminals is innovatively designed to enhance the oxidation resistance of its terminals. Then the ultrasonic transducers are installed on the circuit board by the copper claw spring instead of welding. In addition, the waterproof miniaturized ultrasonic transducer is replaced by the fully covered waterproof sound permeable membrane and the non waterproof miniaturized ultrasonic transducer. The experimental results demonstrate that the quality of the signal transmission of the ultrasonic transducer is not affected, and the convenience of replacement and maintenance of the ultrasonic transducer is improved. With this design process, the overall waterproof performance of the system is also significantly enhanced while the system cost is reduced, market future is wide prospect.

Numerical analysis and experiment of critical current of a preliminary CICC model made from quasi-isotropic strands

The rare-earth barium copper oxide (REBCO) tape has a good development prospect in the application of large high field magnets at low temperatures because of its high critical current density and excellent mechanical and electro-magnetic properties. In recent years, some superconducting conductors based on REBCO tapes have been proposed, such as cable-in-conduit conductor (CICC) designed based on TSTC and CORC. In this paper, a type of preliminary CICC model is proposed and fabricated based on the quasi-isotropic strand. The critical current characteristics of the model and the contact resistance of copper terminals are analysed, respectively. Firstly, the critical current of a partially-filled superconducting CICC is calculated by self-consistent model at 77 K/self-field. Then, a preliminary CICC experimental sample is made and tested to measure its critical current. Finally, the critical current of a full-size superconducting CICC under different magnetic induction intensities and external magnetic field orientations at 77 K and 4.2 K are also calculated, respectively. The results provide another CICC candidate for the application of large high field magnet in the future.

Current transfer length in individual superconducting tape and quasi-isotropic superconducting strand

In the practical applications, superconducting cable should be connected to the power supply by copper terminals. The lap joint between the superconducting cable and copper terminals has some significant effects on the current transfer length (CTL). Firstly, three kinds of soldering methods for an individual high temperature superconducting (HTS) tape are modeled and its CTL is calculated. Then, the distributions of electric field and current along a quasi-isotropic superconducting strand are simulated. Lastly, the CTL of a quasi-isotropic strand is measured by the distribution of electric potential along the strand. The results of simulation and experiment indicate different soldering methods have great influence on the CTL of the superconducting tape/strand.

A critical analysis of a reliability study of ball grid array electronic components submitted to thermal aging and board-level drop test

In the present study, a previous solder joint reliability study is revisited. The results of drop tests conducted on Ball Grid Array (BGA) electronic components mounted onto printed circuit boards with copper terminals coated with Organic Solder Preserver (OSP) submitted to aging heat treatments are studied, focusing on the possibility of identifying switches in failure mechanisms with increasing time-to-failure. The results are discussed based on microstructural characteristics of lead-free solders and its influence on crack propagation. The failure mechanisms encountered are discussed, as well as the explanations given by other authors in the literature for the seemingly contradictory results obtained. The wide range of competing failure mechanisms activated during drop tests and microstructural features such as morphology of phases encountered and the presence of voids contribute significantly to the dispersion of the data, and should be taken under consideration whenever reliability studies based on drop tests are performed. Although this feature is not usually considered in reliability tests, Weibull analyses are efficient to identify the occurrence of competing or switching mechanisms, and even at what point of the life expectance each one is likely to take over.

A Functionalized Paper Strip‐Based Platform for Rapid Detection of Anticancer Drug Concentrations

This article presents a compact, low‐cost, robust, and flexible test platform for determining the concentration of drugs in fluids. This device is based on a PVC foil card containing copper conductive foils in which disposable paper test strips are inserted. The paper test strips are overlaid with deposition of multiwalled carbon nanotubes (MWCNTs) acting as a sensing layer. When a paper test strip is inserted into the test card, the conductive path between two copper lines is established. A drop of test fluid on the sensing MWCNT layer changes the conductivity in a concentration‐dependent manner, enabling calculation of the drug concentration after measurement of the electrical resistance at the copper terminals. An equivalent electrical circuit was also proposed to model the response of the fabricated sensor. It was shown that model parameters are dependent on the concentration of the cytostatic drug methotrexate. Additionally, the fabricated sensor demonstrated the ability to differentiate the same concentration of methotrexate and cyclophosphamide. The complete readout electronics and polynomial transfer function for calculating drug concentrations were also developed and are presented.

Development and study of low-cost VACNT/PDMS stretchable and resistive strain sensor

This study introduces fast manufactured (4−5 hours) vertical aligned carbon nanotubes/polydimethylsiloxane (VACNT/PDMS) stretchable sensor for aircraft structures and polymer composites. The VACNT growth method from thermal CVD with camphor and ferrocene precursors create a dense and homogeneous CNT structure with many ohmic conducting paths that surpass any more resistive tunneling phenomena. The extensive AC/DC piezoresistive performance investigation shows ohmic conduction. The VACNTs/PDMS sensor presented high linearity (r2 = 0.99) under ∼20 % strain with an average gauge factor of 3.28 at DC measurements and minor resistance variations (0.052 %) attributed to the copper terminals electrodeposition. An important feature is the resistance value compatible with conventional extensometry equipment. The DC gauge factor was ∼60 % higher than the conventional metallic strain gauge allowing measurements within a wider strain range.

Design and Test of Current Leads With Parallel HTS Tapes for MRI Applications

The design, analysis and experimental test of a High Temperature Superconductor (HTS) current lead with parallel HTS tapes for MRI applications are presented. Two HTS tapes are electrically shunted in parallel in each current lead to increase its current-carrying capability. Analytical and finite element analysis has been conducted to investigate the current distribution of parallel HTS tapes under the impact of various design parameters, including the geometry, symmetricity and resistance of copper terminals, and the resistance of the interface between copper terminals and the HTS tapes. The analysis concludes that the electric resistance from the copper terminal to each of the parallel HTS tapes needs to be relatively close in order to balance the current sharing between two tapes. Making the copper terminal electrical resistance dominantly greater than the interface resistance would result in a robust current leads design. The FEA simulation meets well with prototype HTS leads test result.

Prevention of Galvanic Corrosion between Copper Terminals and Aluminum Wires by Surface Treatment

Prevention of Galvanic Corrosion between Copper Terminals and Aluminum Wires by Surface Treatment

Characteristics of resistance projection–welded aluminum-copper interconnects

This paper describes the use of resistance projection welding of lap joints between tinned copper terminals with flat aluminum conductors. With the exception of resistance brazing, resistance welding, which has been established for many decades, is currently not used for joining dissimilar metal joints made of copper and aluminum. The use of this technology could potentially result in particularly cost-effective joints that are easily scalable to different sizes of terminals. For the necessary current density during the welding process, a mechanically embossed welding projection in the copper conductor surface is required. During the welding process, the projection moves into the softer aluminum material without being deformed. The projection expresses part of the brittle liquid intermetallic compounds produced. Shear tensile tests, electrical conductivity measurements and micrographs are used to assess the technical properties of the joint. The presented results show that the created intermetallic joint has good electrical and mechanical properties despite pronounced intermetallic AlCu layers.

Reliability of printed power resistor with thick-film copper terminals

This paper is focused on the thick-film power resistors with copper terminals. These terminals are created by the new Thick Printed Copper (TPC) technology. This technology is based on sequential screen printing and firing of copper paste in nitrogen atmosphere on an alumina substrate. Thick-film power resistor with copper terminals represents a potential replacement of standard wirewound power resistors and allows the direct integration of resistors on TPC substrates. Printed resistors on TPC substrates can be supplemented with discrete electronic components which creates the possibility to realize really complex power electronic circuits. The direct integration of printed components is not possible in case of using the standard Direct Bonded Copper (DBC) technology. The main benefits of printed resistors based on TPC technology are their low thickness and good thermal conductivity. The low thickness of resistors is important for miniaturization of final electronic devices. The resistor main electrical parameters as the temperature coefficient of resistance, temperature coefficient and nominal resistance value after dry heat aging and after thermal cycling, insulation resistance, dielectric strength etc., are described in this paper.

Density Functional Theory Study of Mercury Adsorption on CuS Surface: Effect of Typical Flue Gas Components

Copper sulfide (CuS) has been proved to be a potential alternative to traditional sorbents for control of elemental mercury (Hg0) emissions downstream of the wet flue gas desulfurization (WFGD) systems. However, the detailed reaction mechanisms involved in Hg0 adsorption over CuS surface are still unclear. The density functional theory was applied to investigate Hg0 adsorption over CuS(001) surface. The results indicated that the chemisorption mechanism was responsible for Hg0 adsorption over CuS(001) surface. The formation of Hg–S and Hg–Cu bonds was confirmed by depicting the projected densities of states profiles. The binding energies of Hg0 suggested that the crystal surface with two sulfur terminations [labeled CuS(001)–S-2] exhibited a better Hg0 adsorption activity than the crystal surface with copper and sulfur terminations [labeled CuS(001)–Cu/S]. Moreover, the adsorption of the flue gas components downstream of WFGD (oxygen, sulfur dioxide, and water vapor) was studied to understand the effect o...