Electrodeposition Of Silver Research Articles

スクリーン印刷で形成した銀配線におけるエレクトロケミカルマイグレーションの電気化学インピーダンス評価

Electrochemical migration processes on two screen-printed silver wiring electrodes were investigated using electrochemical impedance spectroscopy. The impedance measured immediately after initial growth of silver dendrites on the cathode shows three capacitive loops. A loop in the low frequency range was dependent on the electric double layer capacitance and reaction resistance of electrodeposition of silver and oxygen reduction on the cathode. The capacitive loop diameter in the low frequency range decreased with dendrite growth. A capacitive loop in the middle frequency range was attributed to the dissolution reaction of silver on the anode. Results showed that a capacitive loop in the high-frequency range was related to the interelectrode capacitance between the silver wiring electrodes and the water film’s solution resistance. Curve fitting was performed for the impedance spectra by assuming an equivalent circuit. The calculated impedance spectra showed good agreement with experimental results: the reaction resistances and double layer capacitances varied remarkably with dendrite generation, suggesting that the present silver wiring electrode is applicable to an electrochemical migration monitoring sensor.

Effect of non-stationary current regimes on the morphology of silver electrodeposits

This work is concerned with the use of reverse current regimes in order to form small-grained and compact silver deposits during the electrorefining process. Several parameters were varied, i.e., i) anodic overpotential, ii) cathodic vs. anodic time ratio and iii) duration of the anodic pulse. After optimization of these parameters, phosphate ions were added and the electrolyte was stirred. The effects of a rise of the anodic overpotential on the grain sizes of the silver deposit and compactness were studied. Prolongation of the anodic time had a similar influence but with a decrease in current efficiency. An increase of the cathodic vs. anodic time ratio caused an enlargement of the grains and a decrease in the compactness of the deposit. Optimal morphological characteristics were obtained when PO3-4 were added and the electrolyte was stirred.

Electrodeposition of Mirror-Bright Silver in Cyanide-Free Bath Containing Uracil as Complexing Agent Without a Separate Strike Plating Process

A cyanide-free silver plating bath containing uracil as a complexing agent was investigated. The electrochemical properties of a silver complex were studied on a disk glassy carbon electrode by means of cyclic voltammetry and a rotating disk electrode. The brightness and adhesion of silver deposits obtained from this silver plating bath onto copper substrates in the absence and presence of polyethyleneimine (PEI) were evaluated. Mirror-bright and good adherent silver deposits could be obtained without a separate strike plating process when PEI as an additive was added. Differential capacitance studies indicated that competition adsorption between PEI and uracil molecules occurred on the silver surface. The electrochemical displacement rate of silver by base metal (e.g., copper) was very slow compared with that in a typical cyanide strike bath from the results of electrochemical quartz crystal microbalance studies. The surface morphology of silver deposits characterized by scanning electron microscopy illustrated that, with the addition of PEI, the grain size of the deposits decreased from hundreds to tens of nanometers.

Impedimetric aflatoxin M 1 immunosensor based on colloidal gold and silver electrodeposition

An impedimetric immunosensor based on colloidal gold and silver electrodeposition for the detection of aflatoxin M 1 (AFM 1) herein is reported. An indirect like competitive ELISA procedure was performed on screen-printed electrodes (SPEs) in presence of anti-AFM 1 gold-labelled antibodies. Silver was chronoamperometrically electrodeposited at a fixed applied potential and for a determined period of time to amplify the signal. The calculated charge transfer resistance ( R ct) was found to correlate well with the concentration of AFM 1. The linear working range of the described AFM 1 immunosensor ranged between 15 and 1000 ng/L with a limit of detection (LoD) equal to 15 ng/L (R.S.D. = 20%). Impedimetric results were confronted with linear sweep voltametry (LSV) and corresponded well to this technique.

Electrodeposition of silver–tin alloys from pyrophosphate-cyanide electrolytes

Using cyclic-voltammetric techniques, a pyrophosphate-cyanide electrolyte for the electrodeposition of compact Ag–Sn alloy coatings is investigated. This electrolyte is suited to further investigations on the alloy composition, structure and properties. The electrodeposition of coatings with up to 40 wt% Sn is possible from the investigated complex electrolytes. The alloy surpasses the saturation limit of the silver lattice with Sn and allows the formation of coatings with phase heterogeneity. At high tin content an ordered spatial distribution of different alloy phases on the cathodic surface can be observed. The pattern formation in this system looks very similar to the phenomena and structures observed during electrodeposition of other silver alloys, such as Ag–Sb, Ag–Bi and Ag–In.

Silver electrodeposition from water–acetonitrile mixed solvents and mixed electrolytes in the presence of tetrabutylammonium perchlorate. Part I—electrochemical nucleation on glassy carbon electrode

Nucleation and growth of silver, electrodeposited from water–acetonitrile (CH3CN from 0 to 100% by volume) mixed solvents on glassy carbon electrodes, was studied by means of double-sweep voltammetry, current–time transients (CTT) and scanning electron microscopy (SEM). The effects of the addition of the specifically interacting tetrabuthylammonium cation were also investigated. From voltammetries, the formal potential, the nucleation potential and the cathodic current efficiency have been evaluated as a function of the mixed solvent composition. The key role on nucleation kinetics of transferring Ag+ from the bulk phase to the CH3CN-enriched electrode/solution interphase has been highlighted. CTT transients were described by a model combining instantaneous and progressive nucleation mechanisms. SEM images highlighted the effects of the presence of the organic solvent, which yields to a more regular growth, and of the quaternary ammonium salt, which exhibits grain-refining properties.

Silver electrodeposition from water–acetonitrile mixed solvents in the presence of tetrabutylammonium perchlorate

In this paper, surface-enhanced Raman spectroscopy has been used to investigate the electrode/electrolyte interface during Ag electrodeposition from water–acetonitrile mixed solvents. The reactivity of acetonitrile during Ag electrodeposition has been monitored, promoted by the electrocatalytic activity of silver clusters electrodeposited onto the electrode surface. The effect of the addition of tetrabutylammonium cations to the mixed solvents has been investigated and its adsorption and tilting on the silver surface has been followed as a function of the cathodic overpotential.

Polarization curves in the ohmic controlled electrodeposition of metals

The conditions under which ohmic controlled metal electrodeposition occurs are discussed using a simple mathematical model. It is shown that ohmic controlled electrodeposition can be operative if the value of the exchange current density for the electrodeposition process is more than 10 times larger than the corresponding value of the limiting diffusion current density. In this case, a linear dependence of the current density on overpotential up to the value of the limiting diffusion current density can be observed. On the other hand, the initiation of dendrite growth under these circumstances is possible, even at very low values of overpotential, at the moment when the limiting diffusion current density is attained in potentiostatic electrodeposition. In this way, instead of a limiting diffusion current density plateau, an inflection point on the polarization curve can be observed, since dendritic growth is followed by an increase in the deposition current density. At the same time, it is shown that the ensemble of tips of dendrites can behave as an ensemble of microelectrodes working independently under mixed or activation control due to the absence of a common diffusion layer. This was confirmed by deposition of copper on a copper dendritic electrode and by silver electrodeposition from a silver nitrate solution onto a graphite substrate.

Kinetics of silver electrodeposition from thiocarbamide solutions at a regular surface coverage with sulfide ions

Kinetics of silver electrodeposition in the presence of sulfide ions is studied on electrodes renewed by cutting off a thin surface layer, at a controlled time of contact of the “fresh” surface with the electrolyte. Solutions containing 10−2 M AgNO3, 0.1 M thiocarbamide, 0.5 M HClO4, and from 2 × 10−6 to 1.5 × 10−5 M Na2S are studied. It is shown that under the studied conditions, the effect of silver electrodeposition on the surface concentration of sulfide ions is insignificant. As the concentration of sulfide ions in solution and their coverage on the electrode surface θ increase, the cathodic polarization decreases. Tafel curves plotted for θ = const are used in estimating the exchange current i0 and the transfer coefficient α. It is shown that α ≈ 0.5 and weakly depends on θ, whereas the exchange current increases with the increase in θ by an approximately linear law from 10−5 A/cm2 at θ ≅ 0 to 10−4 A/cm2 at θ = 0.43. The obtained data are compared with the results of kinetic studies of silver anodic dissolution in similar solutions.

Surface roughness of thin silver films pulse-plated using silver cyanide-thiocyanate electrolyte

We investigated the effect of the pulse current density, current-on time and current-off time on the surface roughness of a silver thin film that was pulse-plated using a silver cyanide-thiocyanate electrolyte. The interface width, which is defined by the root mean square of the fluctuations in the height of the surface, is found to decrease rapidly with the current-off time and to increase with current-on time. However, it should be noted that when the value of current-off time is sufficiently large, the interface width decreases with pulse current density. These experimental results indicate that by appropriate selection of the current-on time and current-off time, we can fabricate silver electrodeposits with minimal surface roughness. We have discussed the influence of these three parameters on the interface width from the viewpoint of the cathode potential and adsorption.

Characteristics of Silver Electrodeposition Solution and Silver Film Fabricated by Electrodeposition with Additives for Interconnection

As the electrodeposition reaction is a heterogeneous reaction including both material transfer and electrochemical reaction, this study tries to find out the reaction mechanism about Ag electrodepostion used as semiconductor interconnection using rotating disk electrode system (RDE system). Considering the environmental problem, non-cyanide Ag electrodeposition solution has been carried out. With varying the process conditions of a certain range including the rotating speed of RDE, applied voltage, and temperature etc., obtained the electrodeposition rate of Ag according to the reaction time. The rate determining step was clarified with the activation energy(Ea) of the electrodeposition reactions for the each process conditions estimated from Arrhenius Plot. Activation energy of Ag in the temperature range between 18°C and 32°C was 3.2kcal/mole. The electrodeposition rate of Ag seems to be controlled mass transport. With the electrodepositon solution mentioned above, the characteristics of silver thin film and bottom-up filling capability were investigated by DC or pulsed electrodeposition method. Especially, the effects of additives on the properties of bottom-up filling of Ag were studied.

67.1: Active Matrix Electronic Paper with Silver Electrodeposition

AbstractElectronic paper (3.5 inch & 113 ppi) driven by active‐matrix using silver electrodeposition has been developed. It has a reflectivity of at least 60%, and a contrast ratio of at least 20, resulting in realizing visibility equivalent to paper. By discovering a new halogen‐free silver salt electrolyte composition, driving stability, a gray color tone, and bi‐stability have been considerably improved.

Thick silver electrodeposition on copper substrate for 109Cd production

Silver electrodeposition on copper substrate was investigated for production of 109Ca. The electrodeposition experiments were carried out by the alkaline plating baths. The optimum conditions of the electrodeposition of silver were: 4.1 g/1 silver, pH 10–12, DC current density of ca. 4.27 mA·cm−2 at 40–50 °C temperature with 100% current efficiency.

A SERS Investigation of Cyanide Adsorption and Reactivity during the Electrodeposition of Gold, Silver, and Copper from Aqueous Cyanocomplexes Solutions

In this paper, we report on the reactivity of adsorbed cyanide deriving from ligand release during metal electrodeposition from cyanocomplex solutions of Au(I), Au(III), Ag(I), and Cu(I) in H2O and D2O. When CN- is adsorbed at cathodic potentials in excess of the HER threshold, metal-dependent reactivity can be detected by SERS. Finite surface coverages with adsorbed CN- at such cathodic potentials can be obtained only if CN- is delivered directly to the cathode surface as by decomplexing of the cyanocomplexes of the metals undergoing cathodic reduction. In Au(I) and Au(III) baths, AuCN- reacts with hydrogen-related species to yield adsorbed CH2NH and CH3NH2. Similarly, in Ag(I) baths, AgCN- reacts to polycyanogens. No reactivity of CuCN- was found, under otherwise identical conditions. Our conclusions are supported also by dedicated DFT molecular computations.

Comparison of electrodeposition of silver in ionic liquid microemulsions

Both ionic liquid (IL) and water are typical green solvents and have high electric conductivity. The use of IL microemulsions as templates and media for electrochemical synthesis of nano-materials is attractive. In this work, water-in-ionic liquid (W/IL) microemulsion and ionic liquid-in-water (IL/W) microemulsion were prepared, in which hydrophobic ionic liquid 1-butyl-3-methylimidazolium hexafluorophosphate was used. The cyclic voltammetry (CV) behavior and electroplating in the W/IL and IL/W microemulsion systems containing silver nitrate were investigated for the first time. Both the CV curves exhibit the presence of reduction and oxidation peaks corresponding to the deposition and dissolution of silver from the two microemulsion systems. However, the CV obtained from IL/W microemulsion system exhibits a crossover, which is different from that obtained from W/IL microemulsion system. The electrodeposits obtained from W/IL microemulsion system are nano-granular, while those obtained from IL/W microemulsion system are planar. These results are attributed to the different microenvironments of the microemulsions.

Electrodeposition of silver from the ‘distillable’ ionic liquid, DIMCARB in the absence and presence of chemically induced nanoparticle formation

The reduction of Ag + to Ag 0 has been studied electrochemically at glassy carbon electrodes using the techniques of cyclic voltammetry and chronoamperometry. Ag + is known to be chemically reduced to form Ag 0 nanoparticles by moieties present in the ‘distillable’ room temperature ionic liquid, DIMCARB (synthesised from Me 2NH and CO 2 in a 1.8:1 ratio) which is defined by the following equilibria: CO 2 + Me 2NH ↔ Me 2NHCOOH + Me 2NH ↔ [Me 2NH 2] +[Me 2NCOO] −. At short reaction times in DIMCARB and when the contribution of the chemical reaction is small, Ag + is electrochemically reduced to Ag 0 and deposited onto a glassy carbon electrode via a progressive nucleation and growth mechanism. At long reaction times, when Ag 0 nanoparticles are present and become attached to the glassy carbon surface, Ag + also is electrochemically reduced and deposited via a 2D–2D nucleation and growth mechanism onto Ag nanoparticles attached to the electrode surface. Images obtained during the course of the electrodeposition reaction by atomic force microscopy reveal that a compact film of Ag also is deposited onto glassy carbon in the presence of nanoparticles. Calculation of the diffusion coefficient of Ag + in DIMCARB is complicated by the chemical formation of Ag 0 but is estimated to lie in the range of 2.1–3.0 × 10 −7 cm 2 s −1.

Selective silver electroseparation from ammoniacal thiosulfate leaching solutions using a rotating cylinder electrode reactor (RCE)

A systematic electrochemical study at controlled potential, using a rotating cylinder electrode reactor, was carried out on a synthetic solution with composition 0.2mol/L Na 2S 2O 3, 0.05mol/L CuSO 4, 0.025mol/L EDTA, 0.6 mo/L NH 3, 1 × 10 − 3mol/L AgNO 3, which simulates actual leaching solution, to determine the conditions which permit the selective silver electroseparation with a minimum interference from the copper ions. The presence of 10 ppm of gold (5 × 10 − 4M Au(I)) was found to enhance the gold–silver alloy deposition, with negligible effect on the copper ions. Those results were compared to that obtained with solutions originating from a previously characterized sulfide concentrate leach, in order to determine the influence of other impurities present in the pregnant solution, on the selective silver electrodeposition, obtaining averaging current efficiencies of 80%, with 90% of silver in the formed deposit and less than 5% of both, copper and lead, with only minor quantities of iron and zinc. Additionally, it was shown that the resulting solution could be recycled back to the leach stage, obtaining similar performances to those produced by the fresh solution, implying that it was not significantly altered in its composition, by the electroseparation process.

Isotropic Effect of Fluid Flow on Scaling of Surface Roughness during Copper Electrodeposition

The effect of fluid flow on the scaling properties of roughness during surface growth is studied by copper electrodeposition (and silver electrodeposition, for comparison) and atomic force microscopy measurements. The electrodeposited surface becomes smoother as the Reynolds number increases. Furthermore, fewer growth sites are observed at higher flow rates. Scaling analysis of the self-affine surface indicates that the saturated root-mean-square height decreases with increasing flow and the roughness depends on the fraction of the limiting current. The experimental scaling exponents can be divided into universal and local exponents, and , where the local growth exponent depends on the flow as expressed by the fraction of the limiting current and is the mass-transfer-dependent component of the roughness exponent. In order to generalize the results, similar experiments with silver electrodeposition show the same trend. The universal roughness exponent and the universal growth exponent are obtained by extrapolation to infinite flow velocity . The scaling exponents are found to be isotropic, as they are independent of the flow direction.

Preparation of Co–Ag films by direct and pulse electrochemical methods

A new electrolytic bath containing sodium perchlorate, thiourea, sodium gluconate, boric acid and silver and cobalt salts, able to favour simultaneous electrodeposition of silver and cobalt, has been developed. A systematic analysis of the effect of cobalt(II) concentration, applied deposition potential, hydrodynamic conditions and electrochemical techniques was made. From this bath, Co–Ag deposits of different composition have been prepared and characterized. Granular deposits were obtained from all the electrochemical deposition procedures tested; more compactness and uniformity were attained when the deposits were obtained by pulse plating method. Electrochemical and compositional characterizations indicated that heterogeneous cobalt–silver deposits were prepared containing some oxi- and/or hydroxylated cobalt species.

Voltammetric and chronoamperometric studies of silver electrodeposition from a bath containing HEDTA

The electrodeposition of silver on platinum from ammonium-buffered solutions containing HEDTA (N-(2-hydroxyethyl)ethylenediaminetriacetic acid) at various concentrations was investigated. Potentiometric titration and voltammetric studies indicated that in the presence of 2.0 × 10−1 M HEDTA, the deposited silver was reduced from a mixture of [AgHEDTA]2− and [Ag(NH3)2]+ complexes, whereas at 2.0 × 10−2 M and 2.0 × 10−3 M HEDTA in the electrolyte, the silver was reduced from the [Ag(NH3)2]+ complexes alone. Hydrodynamic studies showed variation in the diffusion coefficient for the electroactive species in solution, depending on the HEDTA concentration. Chronoamperometric study in a solution containing 2.0 × 10−1 M HEDTA at low overpotential (0.000 V to –0.050 V) showed a transition from progressive to instantaneous nucleation in a single current transient, whereas, at −0.200 V only 3D-progressive nucleation controlled by mass transport was observed. Scanning electron microscope images showed that the silver films produced in silver baths with HEDTA were uniform, without cracks, and fine-grained, regardless of its concentration, while in the absence of HEDTA the morphology was rough and dendritic. X-ray diffraction analysis of the films obtained at various HEDTA concentrations revealed polycrystalline silver, similar to film obtained in cyanide and EDTA/ammonia baths.