Purification of copper foils driven by single crystallization

High-purity copper(Cu) with excellent thermal and electrical conductivity, is crucial in modern technological applications, including heat exchangers, integrated circuits, and superconducting magnets. The current purification process is mainly based on the zone/electrolytic refining or anion exchange, however, which excessively relies on specific integrated equipment with ultra-high vacuum or chemical solution environment, and is also bothered by external contaminants and energy consumption. Here we report a simple approach to purify the Cu foils from 99.9%(3N) to 99.99%(4N) by a temperature-gradient thermal annealing technique, accompanied by the kinetic evolution of single crystallization of Cu.The success of purification mainly relies on(i) the segregation of elements with low effective distribution coefficient driven by grain-boundary movements and(ii) the high-temperature evaporation of elements with high saturated vapor pressure.The purified Cu foils display higher flexibility(elongation of 70%) and electrical conductivity(104% IACS) than that of the original commercial rolled Cu foils(elongation of 10%, electrical conductivity of ~ 100% IACS). Our results provide an effective strategy to optimize the as-produced metal medium, and therefore will facilitate the potential applications of Cu foils in precision electronic products and high-frequency printed circuit boards.

Effects of Corrosion Inhibitors on Lubrication Performance of Rolling Oil for Copper Foil

The 2,5-bis（ethyldisulfanyl）-l,3,4-thiadiazole （T561）, benzotriazole （BTA）,1-N, N-bis （2-ethylhexyl） aminomethyl-4-methyl-lh-benzotriazole （IRGAMET39） and I-IN, N-bis （2-ethylhexyl） aminomethyl] methyl benzotriazole （TT- LX） have been evaluated as corrosion inhibitors used in rolling oil for cold rolling of copper foil. The MRS-10A four-ball friction and wear tests have been carried out to compare their tribological properties, and the lubricating performance of rolling oils has been studied through rolling experiments. The oil sample containing IRGAMET 39 has the same PB value as that one containing T561, with the coefficient of friction increased by 35.6% and wear scar diameter decreased by 4%. The minimum rolling gauge has been studied after rolling lubrication, but the results show that inhibitors have no effect on it. Scanning electron microscopy （SEM） and energy dispersive spectrometry （EDS） analyses have indicated that the inhibitor is adsorbed on the copper surface to prevent copper from being corroded easily. In addition, the LEXT OLS4000 laser confocal microscopy has been used to observe the foil surface which shows that the streaks of foil surface are clear, the scratches are shallow and the surface failure is improved effectively.

Copper foils with gradient structure in thickness direction and different roughnesses on two surfaces fabricated by double rolling

Copper foils with gradient structure in thickness direction and different roughnesses on two surfaces were fabricated by double rolling. The two surface morphologies of double-rolled copper foils are quite different, and the surface roughness values are 61 and 1095 nm, respectively. The roughness value of matt surface can meet the requirement for bonding the resin matrix with copper foils used for flexible printed circuit boards, thus may omit traditional roughening treatment; the microstructure of double-rolled copper foils demonstrates an obviously asymmetric gradient feature. From bright surface to matt surface in thickness direction, the average grain size first increases from 2.3 to 7.4 μm and then decreases to 3.6 μm; compared with conventional rolled copper foils, the double-rolled copper foils exhibit a remarkably increased bending fatigue life, and the increased range is about 16.2%.

Study on Surface Adsorption and Inhibition Behavior of Corrosion Inhibitors Contained in Copper Foil Rolling Oil

Adsorption and inhibition behavior of 2,5-bis(ethyldisulfanyl)-1,3,4-thiadiazole(DMTDA) and N-((6-methyl-1H-benzo[d][1,2,3]triazol-1-yl)methyl)-N-octyloctan-1-amine(EAMBA) as corrosion inhibitors contained in copper foil rolling oil have been investigated using gravimetric and electrochemical techniques. Meanwhile, scanning electron microscopy(SEM) and energy dispersive spectrometer(EDS) have been employed to observe the surface topography and analyze the components on copper foil. The results show that the rolling oil containing DMTDA and EAMBA can significantly decrease the dissolution rate and increase the inhibition efficiency of samples, especially in the case of best compounded rolling oil system. The SEM and EDS investigations also confirmed that the protection of the copper foil surface is achieved by strong adsorption of the molecules which can prevent copper from being corroded easily. Reactivity descriptors of the corrosion inhibitors have been calculated by the density functional theory(DFT) and the reactivity has been analyzed through the molecular orbital and Fukui indices. Active sites of inhibitor are mainly concentrated on the ring and the polar functional groups, and in the meanwhile, the distribution is helpful to form coordination and backbonding among molecules and then to form stable adsorption on the metal surface. And this work provides theoretical evidence for the selection of corrosion inhibitors contained in copper foil rolling oil.

Single-crystallization of electrolytic copper foils

Depending on the production process,copper(Cu)foils can be classified into two types,i.e.,rolled copper(r-Cu)foils and electrolytic copper(e-Cu)foils.Owing to their high electrical conductivity and ductility at low cost,e-Cu foils are employed extensively in modern industries and account for more than 98%of the Cu foil market share.However,industrial e-Cu foils have never been single-crystallized due to their high density of grain boundaries,various grain orientations and vast impurities originating from the electrochemical deposition process.Here,we report a methodology of transforming industrial e-Cu foils into single crystals by facet copy from a single-crystal template.Different facets of both low and high indices are successfully produced,and the thickness of the single crystal can reach 500μm.Crystallographic characterizations directly recognized the single-crystal copy process,confirming the complete assimilation impact from the template.The obtained single-crystal e-Cu foils exhibit remarkably improved ductility(elongation-to-fracture of 105%vs.25%),fatigue performance(the average numbers of cycles to failure of 1600 vs.200)and electrical property(electrical conductivity of 102.6%of the international annealed copper standard(IACS)vs.98.5%)than original ones.This work opens up a new avenue for the preparation of single-crystal e-Cu foils and may expand their applications in high-speed,flexible,and wearable devices.

Mechanical properties and microstructure of rolled and electrodeposited thin copper foil

Commercial grade rolled and electrodeposited copper foils from Japan and China were selected, and their mechanical properties and microstructure were investigated. It was observed that there are notable differences in fracture strength, elongation at break and hydrophilicity between rol- led and electrodeposited copper foils. The rolled copper foils have higher tensile strength, lower ductility and larger static contact angle than electrodeposited copper foils. The rolled copper foils contain a [^-fiber texture, and the electrodeposited copper foils have random crystalline orientations. It was also observed that the rolled foils have packed grains, and elec- trodeposited foils have equiaxial grains. The uniform fine grain size and a few substructures of Japanese electrode- posited foils are major reasons for their higher elongation.

Trace bis-(3-sulfopropyl)-disulfide enhanced electrodeposited copper foils

Smooth and strong copper foils are highly required for the development of printed circuit boards and Li-ion batteries.Adding additives is an efficient and low-cost method to enhance electrodeposited copper foils.Here we chose Bis-(3-sulfopropyl)-disulfide(SPS)as the additive and investigated its concentration on the surface roughness and tensile strength of the electrodeposited copper foils.A copper foil with the smoothest surface(Rz=2.1μm)and the highest tensile strength(~338 MPa)was prepared with1.5 mg/L SPS.The contact angle on the copper foil decreased with the reduction of surface roughness.The enhancing mechanism of the SPS was investigated by scanning electron microscopy and X-ray diffraction.The refined grain and enhanced(220)texture were considered to be the radical reason for the smooth and strong copper foils.The electrochemical results prove the suppressing effect is related to the SPS adsorption.

Remarkable Performance in Lithium Battery Copper Foil Market

2018 government work report indicates that'We should strengthen fundamental role of consumption in economic development,as well as promote consumption upgrading and develop new business models of consumer sector.We will extend preferential policies on NEV vehicle purchase tax for another three years'.

Far-reaching Impact of The Fastgrowing Lithium Foil Market on The Development of The Copper Foil Industry

What is the profound impact of the fastgrowing lithium foil market on the copper foil industry and market?How long can the prosperous lithium foil market last?When will the imbalanced supply and demand of lithium foil be solved?When will the acute supply shortage of standard foil be relieved?How

Research and Analysis of Production and New Capacity of China's Electronic Copper Foil Enterprises in 2017

In the light of current fast development of new and expanded copper foil projects of electronic copper foil enterprises and recent adjustment of the main copper foil categories set to be developed by some companies(generally from lithium foil to PCB foil).The secretariat of China Electronics Materials Industry Association e-copper foil branch conducted in March,2017 an extensive and in-depth

融合设备状态和产品要求的电解铜箔制造工艺参数优化

针对当前电解铜箔制造工艺参数的优化仅考虑产品要求的问题,提出了一种融合设备状态和产品要求的电解铜箔制造工艺参数优化方法。首先,为辨识铜箔制造中工艺、设备与产品参数之间的非线性关系,建立了基于神经网络的“工艺-设备”与产品参数的映射模型,并通过构建当前生产模式与历史生产模式的相似性度量方法,确定当前工艺参数的优化初始点;然后,基于所建立的映射模型、设备状态和产品要求构建多目标约束函数,并利用遗传算法优化工艺参数,获得同时满足设备状态和产品要求的最佳工艺参数。企业的生产验证表明:相较于仅考虑产品要求的工艺优化方法,所提方法优化后的工艺参数能在相同的设备状态下获得质量更好的产品,在常温/高温抗拉强度、常温/高温延伸率和树脂剥离强度这5项关键指标上,分别提升了6.1 MPa、6.1 MPa、1.9%、0.7%和0.22 N/mm,生箔制备和表面处理的生产效率也提高了2.65%和7.5%,能够有效保证并提高铜箔的质量和生产效益。

硫脲对电解高性能双面光锂电铜箔性能的影响

为研究硫脲质量浓度对铜箔表面形貌、结构、性能以及电解液电化学行为的影响,以磷铜板为阳极,以硫脲(TU)、羟乙基纤维素(HEC)、聚乙二醇(PEG-1000)和聚二硫二丙烷磺酸钠(SPS)作为组合添加剂,采用自制旋转电镀装置以直流电沉积法在TAl钛辊上制备电解铜箔,并利用扫描电子显微镜、铜箔拉伸强度试验仪以及电化学分析等方法,重点考察了组合添加剂中TU对铜箔表面形貌和物理性能的影响。结果表明:在组合添加剂体系中TU具有较强的极化作用,可以抑制铜核的生长,使铜箔结晶更细致,有效地起到光亮和整平作用并提高铜箔力学性能,且组合添加剂间表现出较好的协同效应。在高性能锂电铜箔的制备过程中,可通过适当调整电解液中硫脲的加入量来改善电解铜箔的各项性能。

Cu对铝/钢CMT熔钎焊接头界面区组织的影响研究

采用冷金属过渡方法,以AlSi5焊丝为填充金属,在5052铝合金和镀锌钢板之间添加铜箔片进行搭接熔钎焊,使用扫描电子显微镜结合能谱分析和拉伸试验机对接头的界面区组织与性能进行研究。结果表明,未加入铜箔时,界面区组织主要由FeAl_(3)金属间化合物组成;铜箔的加入使得界面区组织中新生成了CuAl_(2)金属间化合物,同时改善了Zn在界面区的分布。Zn固溶于Al中,一定程度上抑制了Fe-Al金属间化合物产生。加入铜箔后的试样断裂位置发生改变,接头的承载能力与未加入铜箔的相近。

锂电池用电解铜箔性能调控研究进展

新能源动力锂电池行业向高能量密度的逐步迈进推动了负极铜箔集流体朝超薄、低轮廓、高力学性能等高性能的趋势发展。锂电铜箔作为锂电池的关键辅材之一,其质量和特性对锂电池性能起着重要作用。因此,锂电铜箔的性能精准调控和结构定向修饰对提升锂电池性能具有重要意义。本文从锂电铜箔电沉积技术出发,介绍了铜电沉积原理、过程以及当前铜箔市场情况,归纳总结了锂电铜箔的物理性能、化学性能和表面性能对锂电池电化学性能的影响机制,为后续对铜箔性能精准调控提供参考,并重点综述了生箔工艺参数优化和改性处理这两种综合提升锂电铜箔性能和锂电池性能的方法,分析了铜箔结构修饰的研究现状和发展动态。最后,本文指出了目前电解铜箔作为锂电池负极集流体所存在的问题,并对其未来发展趋势进行了展望,以期为高性能锂电铜箔的研发和应用提供参考。

高强极薄铜箔制造过程的质量管控要素及常见质量问题的应对分析

随着电子产品的小型化、轻薄化,对电解铜箔的厚度和性能都提出了更高的要求,厚度更薄且综合性能更强的高强极薄铜箔的研发及产业化生产已经成为我国亟需解决的重要问题。由于高强极薄铜箔的制造过程复杂且耦合性强,产品质量控制因素多且质量问题影响因素复杂,制造过程的质量稳定性控制已成为制约高强极薄铜箔产业化生产的主要瓶颈问题。因此,以电解式高强极薄铜箔制造过程为主线,对各阶段产品的质量管控要素、质量管控方式以及常见质量问题的应对方法进行了系统的分析和探讨,致力于形成系统化的领域专家经验知识,为高强极薄铜箔制造过程的质量控制及量化稳定生产提供解决对策。

反向处理铜箔微纳组织形成机理及其对力学性能的作用机制

目的第五代移动通信技术(5G)时代,高频高速信号传输过程中由于“趋肤效应”引起的信号损耗甚至“失真”越来越严重,为了解决这一问题,提出了一种反向处理铜箔的新技术,然而国内当前应用的高性能反向处理铜箔(RTF)主要依赖进口,要想在短时间内缩小国内外铜箔性能和生产效率的差距,最终实现这类高端铜箔的国产化,必须在明确该类铜箔微纳结构形成机理及其对性能影响的前提下,加快制备工艺的开发和优化。方法采用电镀法在阴极钛辊上沉积了电解生箔,在其光面进行粗化和镀Zn层等后续处理获得反向处理铜箔,同时以国外反向处理铜箔为参照,采用X射线衍射仪、扫描电子显微镜和透射电子显微镜详细分析其微纳组织与结构,采用激光共聚焦显微镜和万能试验机测量其粗糙度和拉伸性能。结果本工作中的RTF具有与国外商业产品相似的微观结构,由小的等轴晶和较大的柱状晶组成,且包含较多的纳米孪晶,孪晶界占比为30.8%,平均宽度为7.9 nm。S面是均匀的米粒状铜颗粒,而M面是较大的圆锥形铜颗粒。S面上的Zn层均匀致密,厚度约为6.5 nm,只有小部分Zn扩散到基底上形成CuZn3相。但从S面到M面,优选取向从(111)Cu逐渐变为(220)Cu,这与参比RTF略有不同。性能方面,参比RTF的Ra和Rz分别为1.22、1.42μm,抗拉强度为335.10 MPa,伸长率为15.5%,本工作中的RTF具有较低的粗糙度,Ra和Rz分别为0.68、1.03μm,其强度也具有明显优势(393.68 MPa),但延展性低于参比样品。通过对比分析,总结了铜箔在初始外延、过渡生长和电沉积条件控制的生长阶段3个阶段的生长特性,给出了影响每个阶段晶粒生长的主要因素,并且详细讨论了晶粒尺寸和纳米孪晶宽度对铜箔拉伸性能的影响。结论对RTF微观结构和性能的深入研究,有助于找到高性能铜箔国产化“瓶颈”的根源,为高性能铜箔在5G通信领域的进一步发展和应用奠定基础。

过氧化氢-硫酸体系铜箔微蚀工艺及其稳定剂筛选

[目的]过氧化氢-硫酸体系用于PCB(印制线路板)微蚀时存在过氧化氢易分解和微蚀速率过高的问题,研发适宜的稳定剂具有重要的意义。[方法]采用由过氧化氢、硫酸和铜离子组成的溶液对铜箔进行微蚀。先通过研究温度和各组分质量浓度对微蚀速率的影响以确定微蚀液的基础成分,然后设计了一系列不同组合的复配稳定剂,以获得适用于不同工艺需求的微蚀液。[结果]较佳的微蚀基础配方和工艺条件为:浓硫酸140 g/L,双氧水110 g/L,铜离子25 g/L,温度30℃,时间1 min。可选择以四羟丙基乙二胺(EDTP)和乙二胺四乙酸二钠(EDTA-2Na)为主成分,并适当添加磷酸二氢铵(DAP)、N-甲基二乙醇胺(DMEA)、2-氨基-2-甲基-1-丙醇(AMP)、三乙醇胺(TEA)、2-甲基咪唑(2-MI)和1,6-乙二醇(HDO)中的一种或多种作为辅助成分的复配稳定剂。[结论]本研究所得铜箔微蚀工艺具有微蚀速率及铜箔表面粗糙度、形貌可控的优点,能够满足不同的生产需求。

附载体极薄铜箔中新型无机/有机复合剥离层的研究

[目的]剥离层是成功制备和应用附载体极薄铜箔的关键所在。针对目前单一无机或有机剥离层存在的问题,开展了无机-有机复合剥离层的研究,以期实现载体箔/剥离层/极薄铜箔的多界面剥离强度的差异化控制。[方法]首先电沉积制备了35μm厚的铜箔为载体箔,然后依次电沉积Zn-Ni合金层和浸镀2-巯基苯并咪唑(2-MBI)有机层,构建了无机/有机复合剥离层,最后在复合剥离层上电沉积极薄铜箔,制备出附载体极薄铜箔。[结果]Zn-Ni合金层浸镀于2-MBI中时,2-MBI分子可通过其N原子和S原子与Zn、Ni发生键合而锚定在合金层表面,进而构成Zn-Ni合金/2-MBI复合剥离层,令载体箔与极薄铜箔之间的剥离强度适中(约0.083N/mm),且两者剥离后极薄铜箔的光面无Zn-Ni合金残留。[结论]采用无机/有机复合剥离层可实现载体箔/剥离层/极薄铜箔多界面剥离强度的差异化控制,为成功制备附载体极薄铜箔奠定了基础。

低轮廓电解铜箔表面微细粗化工艺研究

目的针对低轮廓电解铜箔剥离强度不足的问题,进行铜箔表面微细粗化处理研究,通过在铜箔表面生成可控形态的针状结构粗化层,以期在不影响低轮廓铜箔表面整体轮廓的条件下,提高铜箔的抗剥离性能。方法采用电化学微细粗化法,以NaOH和K_(2)S_(2)O_(8)的混合溶液为粗化电解液,研究电流密度、NaOH浓度及K_(2)S_(2)O_(8)浓度等主要工艺参数对铜箔表面针状结构形貌、粗糙度及铜箔剥离强度的影响。结果经过微细粗化处理后,低轮廓电解铜箔表面形成了针状多面体结构,在粗化电流密度为1.5 A/dm^(2)、粗化液中NaOH质量浓度为100 g/L、K_(2)S_(2)O_(8)质量浓度为20 g/L的条件下,粗化层形成的针状多面体结构致密且均匀,铜箔的剥离强度提升至0.48 N/mm。结论通过电化学微细粗化法,在低轮廓电解铜箔表面成功制备了针状结构的粗化层,通过优化微细粗化工艺参数,实现了铜箔表面针状结构粗化层的可控制备,在保证铜箔低表面粗糙度的同时,有效提高了铜箔的剥离强度。

胶原蛋白及自退火行为对电解铜箔翘曲性能的影响

电解铜箔在生产过程中极易出现铜箔翘曲度高等问题,严重影响铜箔后续加工和装配,是电解铜箔的关键共性难题之一。本文以不同浓度的胶原蛋白作为添加剂,研究了胶原蛋白对电解铜箔翘曲度的影响,并探讨了其作用机制。结果表明,胶原蛋白的最佳加入量为10 mg/L,此时铜箔的抗拉强度达到382.5 MPa,翘曲度大幅降低至16 mm。随着胶原蛋白浓度的升高,铜箔的抗拉强度不断增加。胶原蛋白通过促进铜箔形成(220)Cu晶面择优取向,降低铜箔表面粗糙度,显著改善铜箔的翘曲度。加入10 mg/L胶原蛋白,铜箔的(220)Cu晶面的织构系数(Tc)增加到57.8%,毛面粗糙度Rz降低到1.9μm,翘曲度降至16 mm。由于胶原蛋白残留在铜箔内部,导致铜箔发生自退火行为。铜箔通过自退火释放了部分残余应力,使得铜箔的翘曲度进一步降低至9 mm。因此,胶原蛋白是一种有效降低铜箔翘曲度的添加剂,并且能够通过之后的自退火行为,进一步降低铜箔的翘曲度。