pH Of Plating Bath Research Articles

Electroless Deposition of Pure Cobalt Film for Realizing Low Resistivity LSI Interconnection

With a scaling trend of LSI interconnection, effective resistivity of Cu/barrier metal interconnect is expected to increase due to increasing electron scattering due to ultrafine dimension smaller than electron mean free path. Therefore, the trend is to substitute Co metal liner for Cu when the line width of LSI interconnect is 10 nm or less. While Chemical Vapor Deposition (CVD) or electrodeposition are discussed as formation method of Co mainly, we introduced electroless deposition (ELD) method. In electroless deposition of Co using Dimethylamine Borane (DMAB), B was incorporated in Co film, and the electric resistivity of the film after heat treatment (400℃ in vacuum, 30 minutes) was 68 µΩ∙cm. In this report, we introduced hydrazine monohydrate as a reducing agent for the purpose of forming ELD pure Co film.ELD Co bath contains cobalt chloride hexahydrate (CoCl2∙6H2O) as metal ion source and hydrazine monohydrate (N2H4∙H2O) as a reducing agent. In addition, some complexing agents were added to prevent Co hydroxide precipitation. Plating bath pH was adjusted to about 12.3 and the CVD-Co film (thickness: 20 nm) on SiO2 and Si was used as substrate for Co deposition. Obtained Co plated film were observed and analyzed by Scanning Electron Microscope (SEM), X-ray Photoelectron Spectroscopy (XPS) and X-Ray Diffraction (XRD). Furthermore, Co plating film was heat-treated at 400℃ in vacuum, and the electrical resistivity of Co film before and after the heat-treatment was measured by four-terminal method.The deposition rate of ELD cobalt bath was about 19 nm/min, and this cobalt film consisted of columnar crystals (Figure 1). If the film surface is rough, it may cause void formation during electroless Co plating in fine via. Regarding the properties of Co film, impurities derived from the reducing agent were not detected from XPS spectral analysis. Co film with few impurities leads to low resistivity because the probability of electron impurity scattering decrease. However, the resistivity of obtained and heat-treated Co film is 53 µΩ∙cm. It is necessary to form the smooth Co film to reduce the electrical resistivity. Figure 1

Electroless deposited black nickel-phosphorous solar absorber coatings on carbon steel: Effect of plating bath pH

One of the challenges of solar energy collection is energy conversion efficiency, particularly the absorbent surface capability to convert solar energy to thermal energy. In this work, nickel-phosphorous (Ni-P) coating was deposited onto a carbon steel substrates using the electroless plating process containing nickel sulfate as the nickel source and sodium hypophosphite as the reducing agent. This study focuses on the study of plating bath pH effect on the light absorption properties of the black surface after blackening process and at the same time maintain the characteristic of protective coating to protect the substrate from corrosion. The electroless nickel plating was conducted at various plating bath pH (4.5, 5.0, and 6.0) for 3 h at a constant bath temperature and composition. Electroless black Ni-P surfaces were obtained through an etching process of Ni-P coating with 9 mol/L nitric acid solution. The surface morphology of Ni-P coating and black Ni-P coating were observed using scanning electron microscopy (SEM). The chemical composition of Ni-P coating deposited at various pH was measured using energy dispersive X-ray (EDX) equipped on the SEM. The SEM results show that black Ni-P coating for pH 4.5 sample has the highest porosity which is 47.1% of the surface area with highest phosphorus content shown by EDX analysis. The cross-sectional analysis showed that the depth of the etching effect occurred only up to the 33% of the coating thickness. The remaining 67% of coating thickness still uniformly attached on the substrate without the presence of any defects or flacking after the etching process. The visible near-infrared spectrophotometer, (VIS-Nir) showed that the black Ni-P coating of pH 4.5 sample had the highest absorption capability which is 92% of light absorption due to its high surface roughness.

The effect of pH of plating bath on electrodeposition and properties of protective ternary Zn–Fe–Mo alloy coatings

Abstract Ternary Zn–Fe–Mo alloy coatings electrodeposition in a sulphate bath with tri-sodium citrate in the pH range 4.8–6.0 was studied. The increase of the plating bath pH from 4.8 to 6.0 leads to the iron content increase from 1.5 up to 7.9 wt% and it is accompanied by a significant decrease in the current efficiency from 76 to 51%. It was demonstrated that molybdenum co-deposition starts at pH > 4.8, because binary Zn–Fe alloy coating without a significant amount of molybdenum was obtained from the plating solution at pH 4.8. The Mo content increases from 0.8 wt% at pH 5.1 to 2.7 wt% at pH 5.7 and 6.0. X-ray diffraction analysis as well as anodic linear sweep voltammetry measurements showed that within the considered plating solution pH range molybdenum modifies zinc microstructure to a very large extent. The deposited at pH 5.4–6.0 Zn–Fe–Mo coatings contain a solid solution of iron and molybdenum in zinc and probably FeZnx phase, where 6.67

Electrochemical Impedance Behavior of Various Composition Quaternary Ni Alloy in 3.5 Wt% NaCl

Zinc and copper addition into electroless Ni-P alloy matrix produces quaternary Ni alloy that exhibits lower corrosion resistance behavior compared to Ni-P and Ni-Cu-P alloy in 3.5 wt% NaCl solution. The corrosion behavior of the alloy is previously studied using the anodic polarization curve measurement. The results show that the corrosion potential of different alloy composition is almost similar to each other for electroless Ni-Zn-Cu-P alloy. However, the surface resistance of the alloy needs to be confirmed by using electrochemical impedance spectroscopy. The alloy was first deposited on an iron substrate using electroless Ni alloy deposition method approximately similar thickness at different plating bath pH of 8.50 and 9.50. The Ni alloy coated substrate was used as working electrode immersed into a solution of 3.5 wt% NaCl. The electrochemical cell consists of Pt and Ag/AgCl/KCl (saturated) as counter and reference electrode respectively. Electrochemical impedance measurement was done at open circuit potential. The measurement started from 100 kHz to 10 mHz with 10 mV of sinusoidal perturbation applied to the cell. Other types of alloy including Ni-P, Ni-Cu-P and Ni-Zn-P, were compared with Ni-Zn-Cu-P alloy. From the results, the Ni-Zn-Cu-P exhibits the lowest corrosion behavior compared to other Ni alloy due to low charge transfer resistance (Rct) observed small inductive loop at low frequency region of the Nyquist plot. Furthermore, the Nyquist plot for Ni-Zn-Cu-P for pH 8.50 and 9.50 showed comparable result; hence, the effect of pH has less effect on corrosion resistance of the electroless Ni-Zn-Cu-P alloy.

Influence of electrodeposition parameters of Ni–W on Ni cathode for alkaline water electrolyser

In this study, different Ni–W coatings, obtained by cheap and technologically simple electrodeposition method, were examined as potential electrocatalysts for the hydrogen evolution reaction (HER). All electrodepositions were done on a Ni mesh substrate from ammoniacal-citrate bath containing different concentrations of Na2WO4. The influence of deposition parameters, such as deposition current density, pH and composition of ammoniacal-citrate bath on electrocatalytic activity of obtained Ni–W coatings toward HER was examined by polarization curve measurements in 6 M KOH at room temperature. The morphology and tungsten content of the Ni–W coatings were investigated by means of SEM and EDS analysis. All investigated electrodes have shown high electrocatalytic activity for the HER. The samples obtained at higher deposition current densities had the lowest overvoltage for the HER. It has been shown that the plating bath pH value is very important parameter in obtaining active coatings. Results of the analysis of polarization curves, morphology of deposited Ni–W coatings and the content of tungsten in the coatings, indicate that the surface roughness of the coatings is responsible for their catalytic activity towards HER.

Textile design application via electroless copper plating

Metallized textile has metallic color with reflective effect and smooth handle. The electroless copper plating on fabric using hypophosphite as a reducing agent is feasible process for design application. This study aims to investigate the appearance of the copper-plated Green-PN fabric produced by electroless plating with different deposition conditions including different nickel sulfate concentrations and pH of plating bath. Various colors were produced after the copper-plated fabrics had been exposed to the copper plating bath at 85°C and pH 8.5 for different time. Design application of the electroless copper plating on Green-PN fabric and Black-CVPN fabric was carried out. The electroless copper plating could change the original appearance of the fabric through the deposition of copper particles on the fabric surface. The final pattern was well-defined using many details such as lines and forms created by the design methods. The study laid the foundation of the electroless copper plating for textile design.

Influence of Operation Parameters on Metal Deposition in Bright Nickel-plating Process

Bright nickel deposits were electrolytically applied on steel in the nickel Watts bath. The effect of some operational parameters on metal deposition in bright nickel plating was investigated. The investigation indicated that the weight of bright nickel deposited on metal during the process of electroplating was affected by plating temperature, voltage, current density, plating bath pH and plating time. The study established that the deposition of best bright nickel was obtained at a plating temperature of 56 o C, current density of 6 A/dm 2 and plating time of 18 minutes. Brightener is used in applications requiring outstanding appearance with minimum thickness of applied nickel plating. It can also be used for heavy deposit applications because it exhibits unparalleled ductility and low stress. Brightener was used in this study to determine the best nickel plating in the process. Boric acid was added for fixing the bath pH. The compositions of the brightener and nickel solution used are included in the text.

Electrodeposition of Fe-Ni-S Soft Magnetic Film

Fe-Ni-S alloy film was prepared on red copper foil by electrodeposition from a acidic bath containing boric acid as a buffer agent and sodium citrate as a complexing agent.The effects of the bath composition,and the deposition parameters on the surface morphology and the composition of the alloy coating were studied by SEM and EDS.As a result,a smooth coating with no crack and little stress was obtained from the plating bath by adding 2 g/L saccharin and 0.4 g/L 1,4-butynediol.The cathodic current density and the plating bath pH have little effect on the coating composition,but the temperature has great effect.Fe73Ni9.5S17.5 film was prepared in optimized plating conditions,and XRD analysis showed that the coating structure is amorphous.The film has good soft magnetic performances with higher saturation magnetization(Ms≈876.25 kA/m) and lower coercivity(Hc≈4.96 kA/m) at room temperature.Cyclic voltammetry and the cathodic polarization curves indicated that thiourea can promote the co-deposition of Fe-Ni-S alloy.

Preparation of the Ni/NiCo<sub>2</sub>O<sub>4</sub> Composite Electrode and Its Properties toward the Oxygen Evolution Reaction in Alkaline Media

A NiCo2O4 spinel composite oxide was obtained by co-precipitation. A Ni/NiCo2O4 composite coating was prepared by composite electrodeposition in a Ni plating solution by mixing with NiCo2O4 powder. The best plating conditions for the composite electrodeposition were investigated by changing factors such as the plating bath pH and the cathode current density jk. The surface morphology, the NiCo2O4 content, and the structure of the Ni/NiCo2O4 composite coating were characterized by scanning electron microscopy (SEM), energy dispersive spectrometry (EDS), and X-ray diffraction (XRD). As a result, the NiCo2O4 content in the Ni/NiCo2O4 composite coating was found to be the highest (30.6%, w) for a bath pH of 6.2 and a cathodic current density jk of 100 mA·cm - 2 . In 5 mol·L - 1 KOH solution the electrocatalytic properties toward the oxygen evolution reaction (OER) of the Ni/NiCo2O4 composite electrode was studied using cyclic voltammetry, electrochemical steady-state polarization, and electrochemical impendence spectroscopy (EIS). Compared with the Ni electrode, the electrocatalytic properties for the OER of the Ni/NiCo2O4 composite electrode improved greatly and the apparent activation energy was reduced to 53.2 kJ·mol - 1 . The apparent exchange current density of the Ni/NiCo2O4 composite electrode toward the OER was 7 times as high as that of a nickel electrode. An electrochemical impendence spectroscopy analysis indicated that the oxygen evolution reaction of the Ni/NiCo2O4 composite electrode was co-controlled by an electrochemical step and a diffusion step. Constant potential electrolysis over extended periods for the OER shows that the stability of the Ni/NiCo2O4 composite electrode is good.

Study of Optimum Conditions for Zinc Plating on Mild Steel

The effect of some process parameters on the weight of zinc deposited on mild steel in a typical electroplating process is reported. The study indicates that the weight of zinc deposited on mild steel during the process is affected by plating temperature, current density, plating bath pH and plating time. The study established that optimum deposition of zinc is achieved at plating temperature of 320C, plating bath pH of 4.4, current density 40mA/cm2 and plating time of 30 minutes. 8.7mg of zinc was deposited at optimum deposition conditions. The profile of the zinc deposited decreases after optimum deposition is attained.

Electroless Nickel Phosphorus Plating on AZ31

One of the major drawbacks to using magnesium parts in automotive applications is poor corrosion resistance, which can be improved with a nickel-boron coating placed on a nickel-phosphorus coating, which, in turn, is placed on a phosphate-permanganate conversion-coating layer produced on the magnesium alloy AZ31. This work reports on the determination of the optimum kinetic parameters for producing a coherent nickel-phosphorus coating using an electroless-procedure phosphate-permanganate conversion-coating layer and for studying the effects of the experimental variables of the electroless plating process on the phosphorus content, surface morphology, and structure of the electroless nickel-phosphorus (EN-P) coatings produced. Measurements of the plating rate as a function of experimental variables such as the compositions of the plating bath constituents, temperature, and pH were implemented using the weight-gain method; the phosphorus content of the EN-P coatings was measured using energy-dispersive spectroscopy (EDS) analysis. The surface morphology of the coating was examined using a scanning electron microscope (SEM); X-ray diffraction (XRD) was used to characterize the structure of each coating. An empirical rate law was determined for EN-P plating on a phosphate-permanganate conversion coating. It is found that the deposition rate of the EN-P coating increases by increasing the deposition temperature, the concentration of free nickel ions, and the concentration of hypophosphite ions in the plating bath. In addition, the deposition rate decreases by increasing both the plating bath pH and the concentration of citric acid in the plating bath.

The effect of nickel electrodeposition on magnetic properties of CoFeSiB amorphous wire

Abstract Nickel films were electrodeposited on rapidly quenched amorphous wires from nitrate bath using a constant voltage. It was found that the pH of plating bath had a very strong effect on the formation of nickel films. The magnetic field, H , dependence of the impedance, of nickel plated (Co 0.94 Fe 0.06 ) 72.5 Si 12.5 B 15 wires have been investigated using a Hewlett-Packard 4294A impedance analyser with 42941A impedance probe. The best elecroplating condition and GMI response were obtained for the plated wire at pH 5 for 30 min plating time.

ニッケルめっき膜の結晶配向性とその残留ひずみに及ぼすホウ酸及び溶液ｐＨの影響

The effects of boric acid and plating bath pH on the average internal strain in electrically deposited nickel films were investigated by an electric resistance wire type strain gauge setup on the reverse side of a copper substrate having a preferred crystal orientation of (200), and the relation between the average internal strain and the preferred crystal orientation of the nickel film was also discussed.It was found that: (1) The internal strain in the nickel films rose rapidly with increasing bath pH near the electrode during hydrogen codeposition. (2) The addition of boric acid to the bath inhibited the hydrogen evolution reaction during nickel deposition, resulting in suppression of the rise in the internal strain in the nickel film. (3) The internal strain in nickel films deposited on the copper substrate rose in the order of (200)<(220)<(111)<disordered in terms of the preferred orientation relative to the ASTM standard for nickel powder. The brightness of the deposits also showed the same dependence on preferred orientation as did internal strain.

無電解析出コバルトメッキ皮膜の構造について

Effects of composition and pH of electroless cobalt plating bath on structure of cobalt plating films were studied mainly by X-ray diffraction method. Cobalt deposits of electroless plating had polycrystalline structure of α-cobalt with close packed hexagonal lattices, and the grain size and orientation of the crystals greatly depended upon the composition and pH of the plating bath. Deposits of finer grain size were obtained, when the growth of crystals was inhibited by adsorbed hypophosphite ions or reduced phosphorus atoms adsorbed on the surface. As the formation and diffusion velocities of cobalt atoms on the crystal plane controlled preferred orientation of cobalt crystals, the deposits with fiber structure were produced.