Effect of wire diameter compression ratio on drawing deformation of micro copper wire

A crystal plasticity finite element model was developed for the drawing deformation of pure copper micro wire,based on rate-dependent crystal plasticity theory.The impact of wire diameter compression ratio on the micro-mechanical deformation behavior during the wire drawing process was investigated.Results indicate that the internal deformation and slip of the drawn wire are unevenly distributed,forming distinct slip and non-slip zones.Additionally,horizontal strain concentration bands develop within the drawn wire.As the wire diameter compression ratio increases,the strength of the slip systems and the extent of slip zones inside the deformation zone also increase.However,the fluctuating stress state,induced by contact pressure and frictional stress,results in a rough and uneven wire surface and diminishes the stability of the drawing process.

Texture evolution and its simulation of cold drawing copper wires produced by continuous casting

The texture evolution of cold drawing copper wires produced by continuous casting was measured by X-ray diffractometry and electron back-scatter diffractometry,and was simulated using Taylor model.The results show that in the drawn poly-crystal copper wires produced by traditional continuous casting,111 and 100 duplex fiber texture forms,and with increasing strain,the intensities of 111 and 100 increase.In the drawn single-crystal copper wires produced by Ohno continuous casting,100 rotates to 111,and there is inhomogeneous distribution of fiber texture along radial direction of the wires,which is caused by the distribution of shear deformation.Compared with 100,111 fiber texture is more stable in the drawn copper wires.Comparison of the experimental results with the simulated results shows that the simulation by Taylor model can analyze the texture evolution of drawn copper wires.

Preparation and Properties of Copper Fine Wire on Polyimide Film in Air by Laser Irradiation and Mixed-Copper-Complex Solution Containing Glyoxylic Acid Copper Complex and Methylamine Copper Complex

Formation of copper wiring on a polyimide film by laser irradiation to a stable copper-complex film consisting of glyoxylic acid copper complex and methylamine copper complex in air has been investigated. A stable metallic copper on the polyimide film was precipitated even in air. Since this copper was generated only in the laser-irradiated parts, direct patterning of copper wiring was possible. It was also found that copper was precipitated by electroless copper plating on the laser-deposited copper wiring and it was possible to thicken the copper wiring by this precipitation. The resistivity of the copper wiring was almost the same as that of the bulk of metallic copper. The developed method—combining laser irradiation to a copper-complex-coated film and electroless copper plating—enables the high-speed deposition of fine copper wiring on a polyimide film in air by a printing process, indicating an inexpensive and useful process for fabricating copper wiring without high vacuum facility and heat-treatment under inert gas.

Fabrication of Copper Wire Using Glyoxylic Acid Copper Complex and Laser Irradiation in Air

Preparation of a glyoxylic acid copper complex and fabrication of fine copper wire by CO2 laser irradiation in air to a thin film of that complex have been investigated. Irradiating laser to the complex thin film spin-coated on a glass substrate, thin film of metallic copper was fabricated in areas that were subjected to laser irradiation in air. The thickness of this thin copper film was approx. 30 to 40 nm, and as non-irradiated areas were etched and removed by a soluble solvent of the copper complex, fine copper wire with 200 μm width was formed by laser direct patterning. The resistivity of this thin copper film depended on the irradiation intensity of the laser and was 3.0 × 10–5 Ω·cm at 12 W intensity (sweep speed: 20 mm/s). This method enables the high-speed deposition of copper wiring in air by a printing process, indicating an inexpensive and useful process for fabricating copper wiring.

Effects of grain boundaries on electrical property of copper wires

By means of annealing at different temperatures, the copper wires with various numbers of grain boundaries were achieved. And the resistivity of copper wires was measured. The results show that with increasing the number of grain boundaries, the resistivity of copper wires increases, the relationship between the number of grain boundaries and the resistivity of cooper wires can be expressed as y =1.86×10 -8 e -0.90/ x . Unlike dislocation and lattice vacant sites, the curve of the grain boundary vs the resistivity is not linear. Grain boundary controls the general trend of the curve, but the type and the quantity of impurity controls the details of the curve.

Bonding mechanism of ultrasonic wedge bonding of copper wire on Au/Ni/Cu substrate

The ultrasonic wedge bonding with d25 μm copper wire was achieved on Au/Ni plated Cu substrate at ambient temperature.Ultrasonic wedge bonding mechanism was investigated by using SEM/EDX,pull test,shear test and microhardness test.The results show that the thinning of the Au layer occurs directly below the center of the bonding tool with the bonding power increasing.The interdiffusion between copper wire and Au metallization during the wedge bonding is assumed negligible,and the wedge bonding is achieved by wear action induced by ultrasonic vibration.The ultrasonic power contributes to enhance the deformation of copper wire due to ultrasonic softening effect which is then followed by the strain hardening of the copper wedge bonding.

9R structure in drawn industrial single crystal copper wires

By using transmission electron microscopy, the microstructures of drawn industrial single crystal copper wires produced by Ohno Continuous Casting(OCC) process were analyzed. The results show that the typical microstructures in the wires mainly include extended planar dislocation boundaries, a small fraction of twins and some dislocation cells sharing boundaries parallel to drawn direction. Besides the typical microstructures, 9R structure configurations were observed in the wires. The formation of 9R polytypes may be caused by the coupled emission of Shockley dislocations from a boundary.

Shearing Mechanism of Straight Thin Copper Wires at Connecting Terminal due to Lightning Current

When a lightning current is impressed through a copper wire, the copper wire would be melted. A straight thin copper wire with a diameter of 0.1 mm,~ is melted due to the specific melting Joule heating （j^2t）m in an adiabatic condition. However, it has been recognized in the experiment that the thicker copper wires of φ1 mm are not completely melted, but sheared mainly at the connecting terminal by a relatively low impulse current. Electro-magnetic mechanical shearing stress, etc. are discussed in addition to the conventional Joule heating. New broken mechanisms were presumed and proved in the additional experiments.

Expansion of Plasma of Electrically Exploding Single Copper Wire Under 4.5kA～9.5kA/Wire

The experimental system for electrically exploding single metal wire has been designed and manufactured. Expansion of the dense plasma column formed from an electrically exploding Cu wire of diameter 30 μm has been studied with a high-speed photographer to obtain the time-dependent radius (R-t) curve. The experimental results demonstrate that the mean expansion rate of the dense plasma column is 1.94 μm/ns, 2.6 μm/ns and 3.75 μm/ns according to the peak pulse current 4.5 kA, 7 kA and 9.5 kA respectively. The results can be beneficial to giving a profound understanding of the early stage of wire-array Z-pinch physics and to improvement on their design.

Predicting size effect on diffusion-limited current density of oxygen reduction by copper wire

The size effect of copper wire radius (0.04–0.82 mm) on the diffusion-limited current density of an oxygen reduction reaction in stagnant simulated seawater (naturally aerated 0.5 mol/L NaCl) is investigated by potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) and compared with the results obtained in 0.5 mol/L H2SO4. In the oxygen diffusion-limited range, size effect is found to occur independent of electrolytes, which is attributed to non-linear diffusion. Additionally, to satisfy application in a marine setting, an empirical equation correlating oxygen diffusion-limited current density to copper wire radius is proposed by fitting experimental data.

Modified Coated Copper Wire as a New Fiber for SPME-GC Analysis of Some Polycyclic Aromatic Hydrocarbons

In this study for the first time, a novel copper Solid Phase Microextraction (SPME) fiber has been introduced for removal of naphthalene, phenanthrene and anthracene from aqueous solution. Copper was used as a solid support, which was at first coated by 3-mercaptopropyltrimethoxysi- lane. A stationary phase of oxidized multi walled carbon nanotube (MWCNTs)) was bonded to the surface of the copper wire. The developed SPME was characterized by IR and Scanning Electron Microscopy (SEM) and coupled to gas chromatography for separation of the analytes. Stability of the fiber, the effect of coating thickness and recovery time were optimized. The MWCNTs film thickness was about 5 μm which was perfect for a rapid mass transfer. The detection limits were at the range of 0.005 to 0.1 μg·L-1. The calibration curves were linear R2 > 0.9813 in the range of 0.01 to 5 μg·L-1. The method has been successfully applied for real samples with standard addition of 5 μL-1 of each sample. Stability study of the fiber to acid and alkali shows that it can be used for more than 50 times.

车用碳化硅功率模块的电热性能优化与评估

由于在开关速度、温度特性和耐压能力等方面的优势,SiC(silicon carbide)功率模块开始逐步应用于电动汽车的电机控制器。电机控制器是电动汽车的核心部件,对功率模块的电热特性要求较高,因此对SiC封装提出了很大的挑战。以主流的HybridPACK Drive模块封装为例,优化设计了模块的驱动回路和DBC(direct bonded copper)布局,并引入了铜线键合技术,协同优化了模块的电热性能和可靠性。此外,采用响应面法优化了椭圆形Pin-Fin散热基板,提升了模块的散热性能。最后,分别制造了优化前、后的SiC功率模块样机作为对比,搭建了双脉冲和功率对拖实验平台,评估了2种方案的电热性能。实验结果显示,当芯片交错距离为芯片宽度的1/2时,所优化的功率模块可以在兼顾电性能的同时,实现更优异的热性能。

稀土Y对铜线材抗氧化行为的影响机理研究

目的针对纯铜线材的抗氧化性能不足问题,通过稀土微合金化制备了含微量Y元素的铜线材,研究稀土Y含量对铜线材抗氧化性能的影响。方法采用扫描电子显微镜(SEM)、EDS能谱仪和X射线衍射仪等表征手段,分析了氧化膜脱落后基体表面形貌以及稀土Y元素在氧化过程中的存在形式与氧化膜的生长过程,揭示了添加稀土元素Y提高纯铜抗氧化性能的作用机理。结果稀土Y的引入提高了纯铜线材的抗氧化性能,在600℃、10 h条件下,Cu-0.03Y线材相对于Cu线材氧化增重率由0.55%降低至0.2%,降幅达63%。稀土元素Y的添加使铜线材的(100)晶面占比减少,(111)晶面占比增多,基体表面易被活化的(100)原子面占比降低,铜线材的抗氧化性能提高。在Cu-0.1Y线材中稀土元素浓度较高时发生偏聚,稀土元素与氧的亲和力大于铜与氧的亲和力,偏聚处形成不连续的稀土氧化物,使氧离子与铜离子的接触反应面积增大,相比Cu-0.03Y线材抗氧化性能降低。结论氧化过程中稀土离子的扩散速率慢、半径大,对铜离子的向外扩散起到阻碍作用,降低了铜离子的扩散速度,提高了铜线材的抗氧化性能。

增材制造铜/钢双金属材料研究进展

铜/钢双金属材料具有力学强度高、物理化学性能优良等优势,在交通运输、电力能源和建筑工业等领域应用前景广阔。然而,传统熔铸工艺在制造铜/钢双金属材料时,容易在铜/钢界面处产生偏析现象,在一定程度上限制了铜/钢双金属材料的发展。与传统工艺相比,增材制造技术不仅能实现复杂加工零件的快速制造,而且在成形过程中较短的保温时间能缓和或消除异种金属材料界面产生的冶金缺陷,进而增强铜/钢双金属材料的力学性能。由于双金属材料是近年来的研究热点,有关增材制造铜/钢双金属材料的综述性文章较少,故综述了近年来激光、电子束及电弧增材制造技术制造铜/钢双金属材料的研究发展现状,分析了各技术的优缺点,并从制备方法、工艺参数及界面合金元素等角度,分析了影响材料界面组织性能变化的关键因素。发现在增材制造铜/钢双金属材料方面,目前激光增材制造技术主要应用于精度要求较高的小尺寸零部件,电子束增材制造技术适用于某些具有特殊性能的合金,如钛合金,而电弧增材制造技术适用于精度要求较低的大型复杂零部件。在铜/钢双金属材料增材制造过程中,界面处易形成显微组织分布不均匀、界面晶粒尺寸差异较大等现象,导致界面处产生应力集中,从而造成材料断裂失效。为解决上述难题,学者们已深入研究第二相形成机理,并采用优化界面处Cu-Fe比例和控制脆相金属间化合物等方式提高铜/钢双金属材料的性能。最后,对目前增材制造铜/钢双金属材料的研究发展现状进行了总结与展望,未来在冶金学和热力学方向上对铜/钢双金属材料仍需进行系统性理论研究,对双金属材料而言需要建立相关模拟数据库,以期为相关从业人员提供精细化指导建议。新型增材制造技术或复合增材制造技术的开发与应用都将成为未来增材制造铜/钢双金属材料研究的重点发展方向。

漆包线热解炉反应器的数值模拟与优化设计

铜漆包线是重要的二次铜资源,回收过程中表面有机漆层的脱除主要依靠热解,热解炉内的不均加热将导致漆层脱除不完全或铜线表面氧化。以某铜漆包线热解炉为研究对象,通过数值模拟的方法对热解炉内燃烧及传热过程进行计算,并根据模拟结果进行了结构优化:使用EDM燃烧模型模拟甲烷燃烧产生热量,得到炉内高温气流的温度场分布及气流流向,发现炉内存在流动死区及罐体加热不均匀问题。根据计算所得流场及温度场对炉膛结构设计进行优化,增加导流挡板及更改出口位置等,增加热解罐受热面积,解决罐体加热不均问题,提升温度均匀性约58%,可提前20 min达到热解所需温度,在工业生产中可以节省耗气量。

国外WIRE-ON-BOLT技术分级准则在我国的适用性研究

在万宁近海暴露场和江津暴露场进行了2次WIRE-ON-BOLT大气暴露试验,分别采用铝丝-碳钢螺栓试样和铝丝-铜螺栓试样,并按LAQUE中心和ASTM标准对万宁和江津的大气腐蚀性进行分级,分级结果表明:国外这2种评级准则难以甄别我国各主要大气网站的腐蚀性,有必要对此进行重新划分。

THQ50-C镀铜焊丝表面锈蚀原因探讨与分析

本工作对THQ50-C镀铜焊丝出现表面锈蚀的影响因素进行了研究和梳理,使用ZEISS-ULTRA场扫描电镜观察了镀铜焊丝表面SEM形貌和焊丝横截面镀铜层与母丝基体结合区SEM形貌,并测量了镀铜层厚度,分析了Cu、O、Fe三种元素的EDS能谱。利用OLYMPUS GX53光学显微镜观察了焊丝横截面镀铜层与母丝基体结合区OM形貌,并对以上观察结果进行了分析。结果表明,THQ50-C镀铜焊丝出现表面锈蚀的根本原因是焊丝加工过程的母丝表面残留了许多微细沟壑、单深坑、细麻点等表面缺陷,这些缺陷宏观表现为树皮棱状凸凹不平的状态。进一步分析认为以上缺陷是由于焊丝母材盘条原有的表面缺陷经拉拔加工后“遗传”到焊丝母丝表面所引起的,从而导致了焊丝表面镀铜层不能完全覆盖焊丝基体形成致密铜层,在焊丝储存过程中由于环境腐蚀而出现了锈蚀现象。

氢氧含量对低氧铜扁线焊接性的影响研究

目的研究TIG焊接过程中低氧铜扁线氢、氧含量对扁线焊接接头的影响。方法以规格为3 mm×2 mm的无氧铜扁线和不同氢、氧含量的低氧铜扁线为研究对象,采用氩弧焊接(TIG)方式,系统研究了不同种类扁线母材及焊接接头的微观组织和焊后力学、电学性能。结果无氧铜扁线经TIG焊接后,焊接接头处没有产生明显的气孔,焊接接头性能良好,其抗拉强度及塑性均与母材的相当。低氢低氧、低氢高氧扁线焊接接头出现少量的气孔,破断力值分别为678 N和654 N。而高氢低氧、高氢高氧扁线焊接接头出现大量的大气孔,破断力值分别为208.7 N和126 N。不同氢氧含量的低氧铜扁线焊后导电率无明显变化。结论低氧铜扁线焊接接头内部气孔的数量和尺寸受氢、氧含量的影响,相比之下氢元素的影响更大。

浸镀时间对镀钯无氧铜线镀层质量的影响

采用直接镀法和扫描电子显微镜研究了影响无氧铜线镀钯层质量的因素。结果表明:浸镀时间和纳米钯粉含量对无氧铜线镀钯层质量有显著影响。当镀液中纳米钯粉的质量分数为2%、表面活性剂OP-10的质量分数为3%时,在室温浸镀15 min以上的无氧铜线表面纳米钯颗粒团聚较少,几乎无露铜现象;纳米钯粉和OP-10的质量分数分别增加至4%和6%时,在室温浸镀20 min的无氧铜线镀层质量最好。此外,当镀液温度升高至约60℃时,浸镀15 min的无氧铜线镀层不均匀,漏铜现象明显。在450℃真空退火后,镀钯铜线的镀层界面结合强度和平整度提高。

A novel integrated microfluidic chip for on-demand electrostatic droplet charging and sorting

On-demand droplet sorting is extensively applied for the efficient manipulation and genome-wide analysis of individual cells.However,state-of-the-art microfluidic chips for droplet sorting still suffer from low sorting speeds,sample loss,and labor-intensive preparation procedures.Here,we demonstrate the development of a novel microfluidic chip that integrates droplet generation,on-demand electrostatic droplet charging,and high-throughput sorting.The charging electrode is a copper wire buried above the nozzle of the microchannel,and the deflecting electrode is the phosphate buffered saline in the microchannel,which greatly simplifies the structure and fabrication process of the chip.Moreover,this chip is capable of high-frequency droplet generation and sorting,with a frequency of 11.757 kHz in the drop state.The chip completes the selective charging process via electrostatic induction during droplet generation.On-demand charged microdroplets can arbitrarilymove to specific exit channels in a three-dimensional(3D)-deflected electric field,which can be controlled according to user requirements,and the flux of droplet deflection is thereby significantly enhanced.Furthermore,a lossless modification strategy is presented to improve the accuracy of droplet deflection or harvest rate from 97.49% to 99.38% by monitoring the frequency of droplet generation in real time and feeding it back to the charging signal.This chip has great potential for quantitative processing and analysis of single cells for elucidating cell-to-cell variations.