脉冲铜沉积层织构及形貌的研究

采用脉冲电沉积工艺制备了铜沉积层,研究了电流密度、脉冲频率和占空比对铜镀层织构的影响。利用X射线衍射仪(XRD)和扫描电子显微镜(SEM)分析了铜镀层的织构和形貌。实验结果表明,低电流密度下为(200)晶面择优取向,高电流密度下为(111)晶面择优取向,频率越高则择优取向越强。低频脉冲下制备的沉积层平整致密。     

Mechanism of copper electrodeposition by pulse current and its relation to current efficiency

The effects of pulse periods and duty cycles on the current efficiency of acid copper plating in a wide range of pulse periods from 200 to 0.02 ms were studied. It was found the current efficiency decreased with shortening pulses in the millisecond range but increased with shortening pulses in the microsecond range. A mathematical model based on the concept of equivalent circuit was employed to simulate the potential responses. Shortening the pulse period was found to change the rate-determining step from charge transfer and surface diffusion to the first step charge transfer. In the millisecond range, the current efficiency decreases with shortening pulse period due to the disproportionation of cuprous ions and the dissolution of copper adatom. However, in the microsecond range, the current efficiency was found to increase with decreasing pulse period because the adatoms are directly incorporated into steps and kink sites, and the disproportionation of cuprous ions or the dissolution of copper adatoms has less chance to occur.     

脉冲电镀锡层可焊性的研究

镀层与基体的润湿程度可用于检测镀锡层可焊性。通过正交实验,以镀锡层可焊性为评价指标,选择了紫铜毛细管表面脉冲电镀锡最佳工艺参数为:平均电流密度1.5 A/dm2,脉冲周期100 m s,占空比10%,搅拌速率20次/m in。研究了平均电流密度在1.0~2.5 A/dm2范围内,对镀锡层可焊性的影响。在相同的平均电流密度1.5 A/dm2下,比较了脉冲电镀与直流电镀2种方法所得镀层的可焊性,脉冲镀锡层的润湿程度明显优于直流镀层,这可能是由于脉冲电镀中阴极浓差极化降低,镀层中的杂质减少,因此镀层的可焊性得到了改善。     

脉冲电镀发展概况

总结脉冲电镀应用于镀铬、镀铜、镀镍及镍合金 ,镀金及金合金 ,镀银及银合金 ,镀钯及钯合金的现状 ,简述了脉冲换向电流电镀 ,脉冲电镀在复合镀层和制备非晶态合金等方面的研究。     

Effect of additives and pulse plating on copper nucleation onto Ru

The impact of organic additives and pulse-plating parameters on the initial stages of copper electrodeposition on Ru is characterized. Microscopy is used to observe 7-15 nm thick Cu deposits, prior to complete coverage of the substrate. Because the nucleus density is very high for the conditions studied here, the counting of individual Cu islands is difficult and an alternative method to analyze the images is presented. Results are compared for different additives for continuous plating and pulse-plating conditions. Pulse plating has a significant impact on the nucleus density. Replacement of Cl⁻ ions with Br⁻ ions of the same concentration yields an increase in the nucleus density at the same current density. A PEG-PPG-PEG block copolymer, when used instead of PEG as a suppressor, appeared to result in high nonuniformity in particle size.     

Current efficiency and crystallization mechanism in pulse plating of hard chromium

The current efficiency of chromium deposition was investigated under conditions of periodic current reversal. It has been demonstrated that the relationship between the anodic and the cathodic charges, Q_a/Q_c, has a strong influence on the current efficiency and the structure of the deposit. A plausible model for the crystallization mechanism during periodic current reversal has been suggested. According to the model, an advantageous chromium structure is maintained during the deposition process because interstitial hydrogen in the chromium lattice is oxidized during the anodic period.Notation F Faraday constant - i _a anodic current density - i _c cathodic current density - m _a mass of dissolved chromium - m _c mass of deposited chromium - M molecular weight of chromium - Q_a anodic charge - Q_c cathodic charge - T cycle time (T _c + T _a) - T _a anodic pulse duration - T _c cathodic pulse duration Greek symbols current efficiency - _a current efficiency of chromium disolution in anodic period - _c current efficiency of chromium deposition in cathodic period - _max maximum current efficiency     

The influence of 2,2′-dipyridyl on non-formaldehyde electroless copper plating

High electroless copper deposition rates can be achieved using hypophosphite as the reducing agent. However, the high deposition rate also results in dark deposits. In the hypophosphite baths, nickel ions (0.0057 M with Ni²⁺/Cu²⁺ mole ratio 0.14) were used to catalyze hypophosphite oxidation. In this study, additives (e.g. 2,2′-dipyridyl) were investigated to improve the microstructure and properties of the copper deposits in the hypophosphite (non-formaldehyde) baths. The influence of 2,2′-dipyridyl on the deposit composition, structure, properties, and the electrochemical reactions of hypophosphite (oxidation) and cupric ion (reduction) have been investigated. The electroless deposition rate decreased with the addition of 2,2′-dipyridyl to the plating solution and the color of the deposits changed from dark brown to a semi-bright with improved uniformity. The deposits also had smaller crystallite size and higher (1 1 1) plane orientation with the use of 2,2′-dipyridyl. The resistivity and nickel content of the deposit were not affected by 2,2′-dipyridyl additions to the bath. The electrochemical current-voltage results show that 2,2′-dipyridyl inhibits the catalytic oxidation of hypophosphite at the active nickel site. This results in a more negative electroless deposition potential and lower deposition rate.     

An experimental study of mass transfer in pulse reversal plating

An experimental study has been made of the limiting pulse current density for a periodic pulse reversal plating of copper on a rotating disc electrode from an acidic copper sulfate bath containing 0.05m CuSO₄ and 0.5M H₂SO₄. The measurements were made over a range of the electrode rotational speeds of 400–2500 r.p.m., pulse periods of 1–100 ms, cathodic duty cycles of 0.25–0.9, and dimension-less anodic pulse reversal current densities of 0 to 50. The experimental limiting pulse current data were compared to the theoretical prediction of Chin's mass transfer model. A satisfactory agreement was obtained over the range of a dimensionless pulse period ofDT/ ²=0.001–1; the root mean square deviation between the theory and 128 experimental data points was ±8.5%.Notation C _b bulk concentration of the diffusing ion (mol cm^–3) - C _s surface concentration of the diffusing ion (mol cm^–3) - D diffusivity of the diffusing ion (cm² s^–1) - F Faraday's constant (96 500C equiv^–1) - i current density (A cm^–2) - i ₁ cathodic pulse current density (A cm^–2) - i ₃ anodic pulse reversal current density (A cm^–2) - i ₃ ^* dimensionless anodic pulse reversal density defined asi ₃/i _lim - i _lim cathodic d.c. limiting current density (A cm^–2) - i _{lim, a} anodic d.c. limiting current density (A cm^–2) - i _PL cathodic limiting pulse current density (A cm^–2) - i _PL ^* dimensionless limiting pulse current density defined asi _PL/i _lim - m dummy index in Equation 1 - n number of electrons transferred in the electrode reaction (equiv/mol) - l time (s) - t ₁ cathodic pulse time (s) - i ₃ anodic pulse reversal time (s) - T pulse period equal tot ₁+t ₃ (s) - T ^* pulse period defined asDT/ ² (dimensionless) Greek letters thickness of the steady-state Nernst diffusion layer (cm) - electrode potential (V) - _de time-averaged electrode potential (V) - _m eigenvalues given by Equation 2 (dimensionless) - ₁ cathodic duty cycle (dimensionless) - ₃ anodic duty cycle in pulse reversal plating (dimensionless) - kinematic viscosity (cm² s^–1) - electrode rotational speed (rad s^–1)     

高电流密度连续生产钢芯镀铜线工艺

介绍了高电流密度连续生产钢芯镀铜线工艺，分析了常见故障的原因并提出了解决措施。     

Localized electrochemical deposition of micrometer copper columns by pulse plating

Micrometer copper column fabrication by localized electrochemical deposition (LECD) was investigated in this study. To obtain columns with uniform diameter, compact structure and a smooth surface, LECD conducted in pulse current (PC) mode was better than that conducted in direct current (DC) mode. A micro-reference electrode was used to monitor the potential at the LECD site. Measurement of this potential permitted estimation of the local copper ion concentration resulting from their dynamic consumption by electrochemical reduction and their supply by mass transport. The electroplating current was measured in order to evaluate the rate of electrochemical reduction. The mass-transfer rate of copper ions was estimated using a theoretical calculation based on diffusion. The surface morphology and internal structure were significantly affected by this local concentration, which was in turn governed by the electrical voltage and the duty cycle employed. The mechanism for LECD conducted in PC mode is discussed.     

低温镀铁时电流密度对镀层性能的影响

研究了不同电流密度下所得低温镀铁层的沉积速率、显微硬度和腐蚀速率。结果表明,当电流密度为14A/dm2时镀层可获得最佳的综合性能。电流密度过低时,镀层沉积速率慢,硬度低;电流密度过高时,镀层表面出现针孔,厚度不均。     

Particle-vapor interaction in deposition systems: influence on deposit morphology

We have here presented methods to study interactions of vapors and particles in systems involving simultaneous deposition of vapors and particles. Besides estimating vapor and particle concentration profiles in the boundary layer adjacent to the deposition surface, their deposition rates are also calculated. In particular, we consider formation of porous preforms by deposition of silica particles and germania particles/vapors during the manufacturing of optical fibers. The process conditions not only dictate the relative rates of germania particle and vapor deposition on the deposition surface, but also controls the fraction of germania crystallinity in the resulting deposit. Moreover, the loss and migration behavior of the deposited germania during the sintering of the porous preform is extremely sensitive to the germania crystalline fraction. Our methods predict the germania weight percent deposited during the deposition process as a function of the deposition conditions, along with the fraction of germania that is crystalline/amorphous. The germania loss and migration behavior during the sintering step is also estimated. In predicting the germania loss and migration behavior, we have developed methods to systematically take into account the simultaneous heating of the preform, sintering of the porous preform, diffusion of gas species through the pores and the gas-solid reaction. Based on the methods developed here for deposition and sintering, processes have been developed which have resulted in sintered glasses with very high germania content (50 weight percent), and, without any glass quality issues of glass seeds, blank splitting or glass crizzling (devitrification).     

低氰脉冲光亮镀金工艺研究

开发出一种低氰脉冲光亮镀金工艺。研究了工艺条件对其镀层性能的影响。本工艺具有施镀电流密度范围宽、镀液稳定可靠以及镀层性能优越等特点。     

The effects of arsenic and lead impurities on the current efficiency and deposit composition in alkaline zinc electrowinning

The influence of lead and arsenic impurities on zinc deposition, current efficiency and deposit composition was examined in the alkaline zinc electrowinning system. It was observed that lead slightly decreases the current efficiency of zinc deposition, and that the detrimental effect on zinc current efficiency which was observed with arsenic was largely suppressed in the presence of lead. This beneficial effect is related to the fact that the arsenic content of the deposit decreased when lead was present in the electrolyte. It was also found that arsenic promotes the deposition of lead. Tin has no effect on the current efficiency of zinc deposition in alkaline solutions, with or without arsenic. The addition of salicylaldehyde to the solution alleviates the deleterious influence of arsenic on zinc current efficiency, but it somewhat increases the cell voltage.     

The influence of mass transport on the effectiveness of particulate bed electrodes

Approximate methods of analysis are presented for the estimation of effectiveness of particulate bed electrodes under activation control. The approximate analytical expressions based on a Taylor series and an asymptotic form give reasonable agreement to exact solutions. The effect of the various system parameters are characterized by two dimensionless group ν² and δ. The influence of mass transport on the rate of electrochemical reaction is treated in an analogous manner and is characterized by an additional dimensionless parameter γ representing the ratio of the maximum (diffusion limited) and equilibrium rates of reaction.     

The influence of pulse plating parameters on microstructure and properties of Ni-W-Si3N4 nanocomposite coatings

Nanosized silicon nitride (Si₃N₄) particles reinforced Nickel-tungsten composite coatings were deposited on the surface of C45 steel sheet by pulse electrodeposition. The effect of duty cycle, frequency, current pattern and presence of Si₃N₄ nanoparticles on microstructure, phases and corrosion resistance and mechanical properties of the coatings were investigated. The Si₃N₄ phase was incorporated into Ni-W alloy matrix uniformly and the inclusion content of in the coating was analyzed by energy dispersive x-ray spectrometer (EDS). The structure, microhardness and surface roughness of the coatings was analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM), Vickers micro-indenter and atomic force microscopy (AFM). The corrosion protection of steel by the coatings was evaluated by weight loss and electrochemical impedance spectroscopy (EIS). Corrosion rates of the coatings were determined using the Tafel polarization test. The results indicated that the duty cycle of 60%, pulse frequency of 1000 Hz, average current density of 5 A/dm⁻², and Si₃N₄ nanoparticles concentration of 30 g/L were the optimal plating conditions. The amount of Si₃N₄ particles incorporated into the coating that were produced under the optimum plating conditions was 2.1 wt%, and the microhardness was 1031 Hv as well as the crystallite size of this coating was 27 nm.     

Improved current efficiency equation for the electrodeposition of copper

The current efficiency of copper deposition is controlled by the extent of the competing hydrogen formation reaction which acts on mass transfer of copper ions together with further mass transfer mechanisms. An available current efficiency equation taking account only of the bubble-induced microconvection fails in the case of forced electrolyte flow. The equation is now extended to all other mechanisms. Results are compared with experimental data.     

整平剂及电流密度对电子封装用铜微凸点电镀的影响

研究了宏观整平剂、微观整平剂及电流密度对铜微凸点表面平整性的影响,探讨了2种整平剂和电流密度对铜微凸点表面的作用机制.镀液组成和工艺参数为:CuSO475 g/L,H2SO4100 g/L,Cl-50 mg/L,整平剂H和W0～10 mg/L,(25±2)℃,60 r/min,1～8A/dm2,35 min.结果表明,宏观整平剂可促进铜的沉积,微观整平剂则可抑制铜的沉积,二者相互配合可改变电镀过程中镀孔的电力线分布,使电流密度分布均匀.在一定范围内提高电流密度可加快铜微凸点的生长.在6 A/dm2下,2种整平剂的质量浓度均为5 mg/L时,可制得结晶细腻、表面平整的铜微凸点.     

Magnetic field influence on mass transport phenomena

The oxidation reactions of hexacyanoferrate(II) and hydroquinone in KCl media were studied on disk platinum electrodes using chronoamperometry under a strong magnetic field (1.74 T). The limiting current measured under magnetic field i_B can be expressed as a function of parameters that control the mass transfer phenomenon by i_B = KC^aD^bd^cν^e?^fB^gn^h. C represents the electroactive species concentration, D the diffusion coefficient of the electroactive species, d the working electrode diameter, ν the kinematic viscosity of the electrolyte, ? the dielectric constant of the solution, B the magnetic field strength, n the number of electrons involved in the redox process and K is a proportionality constant. Contribution of B to the limiting current is well established (g = 1/3), whereas the contribution of D has to be confirmed (b = 1). The aim of this work was to specify the influence of the other parameters for which various results have been published in recent literature. We concluded that i_B = KC^4/3Dd^5/3ν^−2/3?^−7/4B^1/3n, quantifying for the first time, to our knowledge, the drastic influence of the electrolyte dielectric constant.     

The effect of pulsed reverse current on the polarization behaviour of acid copper plating solutions containing organic additives

The polarization behaviour of acid copper solutions containing polyethers, sulphopropyl sulphides and chloride ions was studied using both direct and pulsed reverse current. The effect of these additives on the rest potentials of copper foils immersed in the electrolyte was also studied. Polyethers were found to have an inhibiting effect on the deposition of copper whereas the sulphopropyl sulphides produced a stimulating (i.e. depolarizing) effect. Chloride ion concentration was found to have an influence on the adsorption characteristics of the polyether. The use of pulsed reverse current in solutions containing both polyether and sulphopropyl sulphide was found to inhibit the adsorption/diffusion of the sulphopropyl sulphide at the cathode surface. Thus at higher current densities, above 2 A dm^–2, the inihibiting effect of the polyether produced a shift in the cathodic polarization potential to more negative values as compared with an equivalent current density using direct current. At lower current densities, below 2 A dm^–2, the depolarization effect of the sulphopropyl sulphide was still effective. This effect of pulsed current on additive containing solutions can improve dramatically the metal distribution in low current density areas on plated items. This was illustrated by plating Hull cell panels using both pulsed and direct current.