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Nanocrystalline Ni-Mo alloy coatings with excellent brightness, high hardness, and corrosion resistance were prepared. Nanocrystalline Ni-Mo alloy coating with a Mo content of 14.94 at% was electrodeposited on the copper foil substrate under the optimized conditions with the current efficiency of 51.64%. The electrodeposition behavior of Ni-Mo alloy coatings was studied by cathodic polarization curve and chronopotentiometry. Chronopotentiometry showed that the nucleation rate of Ni-Mo alloys can be accelerated with the increase of current density. Meanwhile, the cathodic polarization curves show that the additives can effectively inhibit the electrodeposition of Ni-Mo alloys. The (2 0 0) and (2 2 0) diffraction peaks of Ni gradually disappeared and the grain size gradually decreased with the increase of Mo content in the alloy coating according to XRD and TEM analysis. Scanning electron microscope (SEM) and confocal microscope observation results show that the coating becomes smoother and denser with the increase of Mo content when Mo content was lower than 14.94 at%, after which the density of the coating saw a decline due to the intensified hydrogen evolution reaction. The microhardness results of the alloy coating show that the microhardness of the alloy coating is related to the solid solution strengthening, texture evolution, and plastic deformation of the alloy. Meanwhile, the alloy coating has a Hall-Petch relationship and inverse Hall-Petch relationship, and the critical grain size is 5.5 nm. The corrosion resistance of Ni-Mo alloy coating is better than that of pure Ni coating, and the corrosion resistance is optimal when the Mo content is about 15 at%. In addition, in the plating solution containing additives, the deposited Ni-Mo alloy coating is smoother and denser, and the hardness and corrosion resistance of the alloy coating is also greatly improved. [Display omitted] • The minimum grain size of nanocrystalline Ni-Mo alloy coatings can reach 2.7 nm. • The hardness and corrosion resistance of nanocrystalline Ni-Mo alloy coatings are higher than pure Ni coatings. • Composite additives can significantly increase Ni-Mo alloy polarization. [ABSTRACT FROM AUTHOR]

Uniform electrodeposition of through-hole (TH) with a high aspect ratio is the key to the reliability of printed circuit board (PCB) interconnection. Inhibitors produce stronger inhibition at high potentials during TH electrodeposition and thus reduce the difference in electrodeposition rates between inside and outside the TH. In this paper, the electrochemical behavior of an ethylene oxide propylene oxide random copolymer (EO-PO) as an inhibitor on the cathode during periodic pulse reverse (PPR) electrodeposition was systematically studied. The results show that EO-PO will rotate under the effect of reverse pulse, and adsorb more strongly on the cathode surface, which inhibits the "cathode stripping" process of the reverse pulse. Through the electrodeposition experiments, compared with direct current (DC) electrodeposition, the PPR method effectively eliminates the copper nodule and improves the concentration window of EO-PO. The results pave the way for regulating and controlling TH electrodeposition with other additives. [Display omitted] [ABSTRACT FROM AUTHOR]

[Display omitted] • Adsorption-coordination mechanism was calculated by quantum chemistry to demonstrate the inhibition effect of MG. • Adsorption-transport mechanism was illustrated to explain the bottom-up growth of cobalt under the influence of MG. • The nucleation and growth of cobalt is 3D diffusion-controlled progressive nucleation process. A novel suppressor, malachite green, was used to achieve bottom-up growth of cobalt in this work. Electrostatic potential, HOMO/LUMO of malachite green was calculated to provide an insight into the interaction between malachite green and metal substrate, while charge distribution, AIM (atoms in molecules theory) analysis and IRI (interaction region indicator) analysis were coupled to analyze the interaction between malachite green and cobalt ions. Adsorption-coordination inhibition mechanism was illustrated to explain the inhibition effect of malachite green. Electrochemical analysis was applied to evaluate malachite green. Cyclic voltammetry was used to confirm the inhibition effect of malachite green, while EQCM analysis demonstrates that the current efficiency was lowered by MG. The nucleation and growth of cobalt is 3D diffusion-controlled progressive nucleation growth under the influence of hydrogen evolution reaction and the compact cobalt coatings could be obtained by surface analysis. The effective MG concentration gradient could be formed within blind vias according to current transient analysis so as to develop electroplating rate difference. The bottom-up growth of cobalt within blind vias was achieved by carrying out electroplating test and the adsorption-transport mechanism was proposed to explain the superconformal electrodeposition of cobalt under the influence of MG. [ABSTRACT FROM AUTHOR]

Abstract: Janus Green B (JGB) and Safranine T (ST) were used as levelers in the through-hole (TH) copper electroplating experiments. Although JGB and ST have a similar part in the structure, the results indicate that JGB is an effective leveler used for TH electroplating whereas ST is not. A uniform plating is obtained using 1ppm JGB as a leveler. In contrast, ST could not increase the value of uniformity power (UP). Electrochemical behaviors of JGB and ST were evaluated by potentiodynamic polarization and galvanostatic measurements using rotating disk electrode (RDE). JGB could effectively affect the cathodic polarization. However, the addition of ST changed the cathodic polarization weakly. Quantum chemical calculations based on density functional theory (DFT) were used to obtain some electronic properties and orbital information. The calculations on frontier molecular orbital suggested that the electron donating ability of JGB was higher than that of ST, which gave rise to stronger adsorption of JGB on the cathodic surface and stronger inhibition of copper electrodeposition on the cathode. Furthermore, the results of frontier molecular orbital and Fukui function distributions showed that the Nor aminoazobenzene region of JGB was the probable reactive site for the adsorption of JGB on the copper surface. [Copyright &y& Elsevier]

Abstract: Adsorption behaviors of N-butyl-methyl piperidinium bromide (PP14Br) at Cu (001) surface under different electric fields were investigated using molecular dynamics (MD) simulations. We predicted PP14Br could be used as a new leveler for through-hole copper electroplating. In the through-hole electroplating experiments, PP14Br was employed as a leveler. The results of electroplating confirmed the prediction. The electrochemical tests were characterized by potentiodynamic polarization and galvanostatic measurements using rotating disk electrode operated at 100 and 1000rpm. [Copyright &y& Elsevier]

[Display omitted] • Suppressing effect of NBT on cobalt electrodeposition is confirmed by electrochemical analysis and in situ Raman spectra. • Accelerating effect of NBT on HER is studied by electrochemical methods and finite element simulation. • Suppressing-accelerating effect of NBT is proposed to illustrate the influence of NBT during cobalt electrodeposition. • Nitrotetrazolium blue chloride and convection is of grain refinement during cobalt electrodeposition. Achieving cobalt superconformal (bottom-up) growth is significantly important. Electrochemical methods, including cyclic voltammetry, electrochemical impedance spectra and EQCM-derived Coulomb-voltage curves, were used to confirm the suppressing influence of new suppressor Nitrotetrazolium Blue chloride (NBT). In situ Raman spectroscopy was used confirm that NBT can effectively adsorb on cobalt surface. Besides, EQCM-derived Coulomb-voltage illustrates that it is more beneficial for cobalt electrodeposition at high pH. The NBT effect on hydrogen evolution reaction (HER) was studied by LSV and chronoamperometry. Finite element simulation is used to investigate the accelerating effect of NBT on HER and convection. Suppressing-accelerating effect is proposed to illustrate effect of NBT. NBT can not only suppress the cobalt deposition but also can accelerate local convection by intensifying HER, which can in turn strengthen NBT adsorption. SEM analysis demonstrates that convection and NBT can refine grain. High-quality cobalt is achieved with low SDT values ranging from 24 μm to 45 μm and high FP values (75.4 % for 150 μm, 88.9 % for 100 μm and 87.2 % for 50 μm). [ABSTRACT FROM AUTHOR]

Three-dimensional ordered macroporous (3DOM) CuIn x Ga 1−x Se 2 (CIGS) film is synthesized by one-step galvanostatic electrodeposition based on polystyrene templates from a special mixture of ionic liquid 1-butyl-3-methylimidazolium tetra-fluoroborate and ethanol. X-ray diffraction pattern, Raman spectroscopy and transmission electron microscopy present the CIGS film has ideal chalcopyrite crystallization. 3DOM CIGS film with high Ga content has photochemical activity and good photo-stability, its band gap is 1.34 eV. This is a simple, feasible and additive free method without selenization process to synthesize 3DOM CIGS film, the film is qualified and available for absorber-layer fabrication or other fields. [ABSTRACT FROM AUTHOR]

The effect of a pulsed laser on the electrodeposition of germanium on indium tin oxide glass in the ionic liquid 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([EMIm]Tf 2 N) was investigated. Cyclic voltammetric analysis of GeCl 4 in [EMIm]Tf 2 N showed that laser irradiation produced a positive shift of the reduction potential and an increase in the reduction current. Laser irradiation influenced the morphology and crystallinity of the Ge deposits. A deposition time of 1200 s gave rise to amorphous Ge deposits when laser irradiation was not applied, whereas laser irradiation led to a polycrystalline branched structure. The length and width of the branched structures were about 9.58 and 2.18 μm, respectively, and the average grain size of the sample was ∼76 nm. The morphology and size of the Ge deposits could be controlled by adjusting the deposition time under laser irradiation. The mechanism of growth of the Ge deposits under laser irradiation was discussed in detail. [ABSTRACT FROM AUTHOR]

[Display omitted] • Synergistic effect of Rhodamine B (RhB) was illustrated to explain the strong suppressing ability of RhB during the reduction of cupric ions. • The strong suppressing influence of RhB was confirmed by electrochemical tests. • Proper RhB is conducive to improving surface morphology and smoothness of copper interconnect layer. • Microvias filling for different blind vias radius is achieved with RhB concentration ranging from 50 mg/L to 150 mg/L. Achieving void-defect copper filling by electrodeposition on microvias is essentially important. Rhodamine B (RhB) is of excellent suppressing ability based on electrochemical analysis. Convection-dependent adsorption analysis demonstrates that 100 mg/L was the optimum value to achieve bottom-up growth. The interaction among sodium 3,3′-dithiodipropane sulfonate, polyethylene glycol, and RhB was investigated and competition adsorption between RhB and SPS is observed. Meanwhile, copper electrodeposition obeys 3D diffusion-controlled progressive nucleation process at low potential but obeys 3D diffusion-controlled instantaneous nucleation process at high overpotential. Density functional theory and in situ Raman spectra were used to study the adsorption behavior of RhB. The calculated results indicates that RhB can effectively increase the energy barrier during copper electrodeposition. The surface morphology is improved and surface roughness is lowered with proper RhB concentration. The influence of RhB on orientation and grain size was analyzed and proper RhB (100 mg/L) is conducive to the formation of Cu (1 1 1) surface and lowering the grain size. Besides, the introduction of RhB can improve the wettability, which is conducive to the bottom-up growth. The electroplating process is optimized and void-defect copper interconnect line with high quality is obtained. [ABSTRACT FROM AUTHOR]

In this work, a combined approach using density functional theory (DFT), molecular dynamic simulations, and electrochemical experiments was developed to study organic additives used for a cyanide-free gold electrodeposition process. When 5,5-dimethylhydantoin (DMH) is used as the complexing agent, organic additives with either imino groups or nitrogenous heterocyclic rings including polyethyleneimine (PEI), 2,2′-bipyridine, and nicotinic acid (NA) were systematically investigated. Electronic properties and orbital information of these studied additives were determined by quantum chemical calculations based on DFT. Compared to the other additives, PEI was predicted as the most promising one for the introduced DMH based gold electrodeposition. The theoretical prediction was further verified by using experimental results. In particular, the cathodic polarization of the gold electrodeposition was significantly improved in the presence of PEI. Also, the resulting gold electrodeposit shows obviously finer crystalline particles largely. In addition, molecular dynamic simulations determined that PEI molecules possess optimized adsorption behavior on the gold surface, suggesting its effectiveness to be additive in the studied cyanide-free Au-electrodeposition electrolytes. [ABSTRACT FROM AUTHOR]

Nanocrystalline Zn–Ni (grain size about 26 nm) alloy coatings were electrodeposited on carbon steel substrates in alkaline bath with 5,5′-dimethylhydantoin (DMH) as the complexing agent. The coatings with 13 wt.%–16 wt.% Ni content and the electrolyte with high current efficiency (> 85%) were achieved at the optimized parameters, i.e., Ni 2 + /(Zn 2 + + Ni 2 + ) ratio 0.32, current density 2 A·dm − 2 , temperature 50 °C and agitation speed 1000 rpm. The electrochemical behavior of the bath has been studied by cyclic voltammetry (CV), chronopotentiometry (CE) and cathodic polarization. Results show that the deposition of Zn–Ni alloys occurs at moderate overpotential and the rotation speed and bath temperature have a strong effect on cathodic polarization curves. The effects of Ni 2 + /(Zn 2 + + Ni 2 + ) ratio, current density, temperature and agitation speed on Ni content and cathode current efficiency were investigated. Studies indicate that the phase structure, grain size, microhardness and corrosion resistance of deposits are directly dependent on Ni content in deposits. The phase structure of deposits changes from a mixture of η-phase and γ-phase to single γ-phase with (411) plane orientation. Furthermore, the grain size decreases with the increase of Zn content in deposits and the increase in current density can also lead to the decrease in grain size. The increase in microhardness of deposits is strongly affected by the increase of Ni content in deposits rather than the Hall–Petch relationship. Zn–Ni alloy coatings with about 13 wt.% Ni content present best corrosion resistance and the bath has a good stability. [ABSTRACT FROM AUTHOR]