Nickel Electroplating Research Articles

Nickel electroplated widely tunable micromachined capacitor

Nickel electroplating is used to fabricate a widely tunable micromachined capacitor. From an initial capacitance of 0.7 pF, the device has a tuning ratio of 5.1:1 including parasitics: this is better than twice any previously reported figure for such devices. A process flow is presented which includes electrode surface roughening for stiction avoidance.

Effects of boric acid on hydrogen evolution and internal stress in films deposited from a nickel sulfamate bath

The effects of boric acid additions on the pH close to the electrode surface, on the hydrogen evolution reaction and on the internal stress in the plated films were studied for the high speed electroplating of nickel from a nickel sulfamate bath at a current density close to the nickel ion limiting current density. The study was carried out at 50 °C and pH 4.0 using a 1.55 M nickel sulfamate plating bath containing boric acid at concentrations ranging from 0 to 0.81 mol L−1. The variation of the internal strain in the plated nickel films was determined in situ using a resistance wire-type strain gauge fitted to the reverse side of the copper electrode substrate. The solution pH at a distance of 0.1 mm from the depositing nickel film was measured in situ using a miniature pH sensor assembly consisting of a thin wire-type antimony electrode and a Ag/AgCl/sat. KCl electrode housed in a thin Luggin capillary. The addition of boric acid was shown to effectively suppress the hydrogen evolution reaction at nickel electrodeposition rates (18.0 A dm−2) close to the limiting current density (~20 A dm−2). Consequently, the solution pH adjacent to the plating metal surface was maintained at a value close to that in the bulk solution and the development of high internal stresses in the deposited nickel films was avoided.

631 Optimization of Nickel Electroplating for High Aspect Ratio LIGA Mold Inserts Fabricated by Synchrotron Radiation from "NewSUBARU"

Currently, standard molding inserts in LIGA or UV-LIGA consists of nickel. However, electroplated Ni has internal stress that leads to significant distortions in thicker deposits and it starts to recrystallize at lower annealing temperatures suffered during molding processes. We investigated optimum electroplating parameters to attain low internal stresses and high strength Ni mold inserts durable among the plastic moldings. We also demonstrated the fabrication of high aspect ratio Ni mold inserts using X-ray lithography at the Synchrotron Radiation Facility "New SUBARU" of Himeji Institute of Technology.

Laser sintered rapid tools with improved surface finish and strength using plating technology

Rapid tooling (RT) is a technology that can contribute greatly in reducing product development cycle. However, currently used RT methods permit smaller, pre-serial production runs to be conducted economically only in a limited number of cases. To make this technology viable for all cases, the quality of the rapid tools should be improved in order to be as close as that obtained in the case of traditional mould. In this regard, direct metal laser sintering (DMLS) technique shows great promise. But the common limitations of the rapid tools produced by DMLS technique are low surface finish, low wear resistance, soft and porous. A comprehensive investigation has been conducted to improve the quality of the RT produced by DMLS technique to an industrial acceptance level. Electroless nickel (EN) plating and semi-bright nickel electroplating have been chosen for their unique characteristics while they are applied either alone or combined with each other to achieve the best possible results. The investigated results demonstrate that the applied techniques possess enormous potential in developing rapid tools.

Hydrogen-induced degradation of PMN-based relaxor ferroelectrics during nickel electroplating

The effects of nickel electroplating on electrical properties of PMN-based relaxor ferroelectrics were studied by measuring the resistance and temperature dependence of dielectric constant and dissipation factor. It was found that the insulation resistivity of the specimens declined nonlinearly with electroplating time. Additionally, the dielectric constant and dissipation factor were reduced and enhanced respectively. X-ray photoelectron spectroscopy (XPS) analysis showed that Nb 5+ and Pb 2+ were partially reduced to Nb 4+ and metallic Pb by hydrogen during nickel electroplating, which consequently generated oxygen vacancies and conductive electrons in view of defect chemistry, thereby the conduction was enhanced. On the basis of our experiments, the degradation of electrical properties of PMN-based ferroelectrics was ascribed to resistive leakage resulting from Nb 5+ and Pb 2+ reductions to lower charge states by hydrogen.

Resistance Degradation of Lead Magnesium Niobate-Based Ceramics during Nickel Electroplating and Recovery Through Air Annealing

Resistance degradation of lead magnesium niobate (PMN)-based relaxor ferroelectrics during nickel electroplating, as well as the recovery of the degraded specimen through air annealing, were investigated by using resistance measurement and X-ray photoelectron spectroscopy (XPS). It was found that the resistivity of the ceramics declined nonlinearly with the electroplating time, and eventually, an obvious degradation occurred. The XPS results showed that parts of and were reduced to metallic Pb and by hydrogen during electroplating. In view of defect chemistry, oxygen vacancies and free electrons were produced, leading to the resistance degradation. It was also found that the degraded PMN-based ceramics could regain its resistivity characteristics after being annealed in air at high temperatures. The correlation of Pb and reoxidation and the resistivity recovery was clarified, which in turn confirmed that the generation of metallic Pb and resulted in the resistance degradation of the ceramics during nickel electroplating. © 2001 The Electrochemical Society. All rights reserved.

Nanostructured diffractive optical devices for soft X-ray microscopes

The new transmission X-ray microscope (TXM) installed at the BESSY II electron storage ring uses an off-axis transmission zone plate (OTZ) as diffractive and focusing element of the condenser-monochromator setup. A high resolution micro-zone plate (MZP) forms a magnified image on a CCD-detector. Both, the OTZ with an active area of up to 24 mm 2 and the MZP with zone widths as small as 25 nm are generated by a process including electron beam lithography (EBL), dry etching and subsequent electroplating of nickel on top of silicon membrane substrates with about 100– 150 nm thickness. The combination of a larger zone width and the usage of nickel zone structures allows to increase the diffraction efficiency of the condenser element at least by a factor of 3 compared to the earlier used KZP7 condenser zone plate in the TXM at BESSY I. Groove diffraction efficiencies of 21.6% and 14.7% were measured for MZP objectives with 40 and 25 nm outermost zone width, respectively.

Composite Electrodeposition to Obtain Nanostructured Coatings

Nanocomposite coatings are obtained by electrochemical deposition of silicon carbide nanoparticles (mean diameter 20 nm) in a nickel plating bath. The influence of nanoparticles on nickel electroplating is studied by electrochemical impedance spectroscopy at cathodic potential, and cathodic polarization diagrams are performed in the electrolyte with and without nanoparticles. We show that incorporation of 20 nm SiC particles into nickel deposits modifies the impedance and cathodic polarization diagrams in correlation with the modification of the surface morphology and crystallinity of the nickel matrix. © 2001 The Electrochemical Society. All rights reserved.

An XPS study on the degradation of lead magnesium niobate-based relaxor ferroelectrics during nickel electroplating

Resistance degradation of Pb(Mg1/3Nb2/3)O3–Pb(Zn1/3Nb2/3)O3–PbTiO3 (PMZNT) relaxor ferroelectrics during nickel electroplating was investigated by resistivity measurement and X-ray photoelectron spectroscopy (XPS) through the appearance of changes in Nb 3d and Pb 4f spectra. It was found that the insulation resistance of the PMN-based ceramics decreased after electroplating. The XPS analysis showed that the ceramic materials had been reduced by hydrogen during electroplating and Nb4+ and metallic Pb were generated. As a result, oxygen vacancies and free electrons were created and, therefore, increased the conductivity of the ferroelectrics. It was also found that Nb5+ reduction was prior to Pb2+ reduction. On the basis of our experiments, two conduction mechanisms involved in the hydrogen-induced resistance degradation were established.

Cement-Waste and Clay-Waste Derived Products from Metal Wastes: Environmental Characterization

Metal hydroxide sludges from the wastewater treatment of metal finishing effluents are complex wastes, mainly inorganic, with a high content of heavy metals and anions. This makes it necessary to employ careful environmental management. In this work, two selected metal hydroxide cakes from the ‘on site’ wastewater treatment of nickel and chromium electroplating activities and the anodizing of aluminium materials were treated with Portland cement and mixed with clay, offering two possibilities of solidification/stabilization prior to landfilling, and reutilization in ceramic products, respectively. The obtained products were characterized by the determination of ecotoxicity values, EC 50 , of the TCLP leachates and the chemical characterization of DIN-38414-S4 leachates. The unconfined compressive strength (UCS) was determined in all derived products. Cement formulations show values of EC 50 higher than 3000mg l -1 and high concentrations of chromium in the DIN 38414-S4 leachates, due to the alkaline medium resulting from the cement addition. The clay/waste products are non-hazardous based on the EC 50 and the low concentrations of heavy metals in the leachates. The paper establishes environmental characterization of both kind of products, showing that there are environmental benefits of waste dosification in ceramic materials.

Corrosion of Nickel Electroplates in Neutral and Acidic Salt-Spray-Fog

By gravimetric method, the corrosion rate of Ni electroplates is determined during the accelerated tests in neutral and acidic salt fog of 5% NaCl solution. In neutral fog, the electroplates corrode uniformly with a small mass loss even during long-term exposure. In acidic fog, corrosion is twice more intense: not only the surface passive layer of dull electroplates becomes broken down, but also, with an increase in the exposure time, surface defects form, which cause even greater losses of metal. Bright Ni electroplates, differing in surface morphology from dull Ni coatings corrode intensely but uniformly. Corrosion of composite Ni–Al2O3electroplates decelerates with time, and they demonstrate corrosion resistance in accelerated tests in both types of media.

Nanofabrication and diffractive optics for high-resolution x-ray applications

Short wavelength x-ray radiation microscopy is well suited for a number of material and life science studies. The x-ray microscope (XM1) at the Advanced Light Source Synchrotron in Berkeley, California uses two diffractive Fresnel zone plate lenses. The first is a large condenser lens, which collects soft x-ray radiation from a bending magnet, focuses it, and serves as a linear monochromator. The second is the objective zone plate lens, which magnifies the image of the specimen onto a high-efficiency charge coupled device detector. The objective lens determines the numerical aperture and ultimate resolution. New objective lens zone plates with a minimum linewidth of 25 nm and excellent linewidth control have been fabricated using Berkeley Lab’s 100 keV Nanowriter electron beam lithography tool, a calixarene high-resolution negative resist, and gold electroplating. Although the condenser zone plate is less critical to the resolution of the instrument, its efficiency determines the flux on the sample and ultimately the exposure time. A new condenser zone plate was fabricated and has a 9 mm diameter, 44 000 zones, and a minimum zone width of 54 nm (optimally the condenser and objective should have the same zone width). It is also fabricated with the Nanowriter at 100 keV using poly(methylmethacrylate) resist and nickel electroplating. The phase shift through the nickel absorber material enhances the diffraction efficiency over an amplitude only zone plate. To evaluate the microscope’s performance transmission test patterns have been made and imaged. Lineout data show modulation for 30 nm lines and 60 (1:2) spaces to be almost 100%. These new diffractive optical elements represent a significant advancement in the field of high-resolution soft x-ray microscopy. Diffractive optical elements have been used to measure the wave front error of an extreme ultraviolet projection optical system. The reference wave is generated by the spherical wave generated by diffraction from a small freestanding pinhole.

Metallic microstructures by electroplating on polymers: an alternative to LIGA technique

In this paper, a new technique of obtaining nickel electroplated layers on polymethylmethacrylate (PMMA) is presented. It consists of four steps. 1. Conditioning. Strongly oxidizing acid mixtures are used for providing roughness on the surface by generating suitable sites for chemical bonding of subsequently applied metals. 2. Nucleation. Using an acidic solution of a mixture of a palladium salt together with a tin salt it can be obtained an adsorbed film on PMMA’s surface that is reduced to metallic form. 3. Electroless nickel plating. This step transforms PMMA into a conductive surface and builds up metal only to provide sufficient conductivity for electroplating. This is achieved in a classical hypophosphite electroless nickel solution. 4. Nickel electroplating. Metallic microstructures are finally obtained by growing up, at the desired thickness, nickel layers on the thin electroless ones, using a standard sulphamate bath for rapid electroforming. This method of obtaining nickel electroplated microstructures was developed to replace the classical Lithographie, Galvanoformung, Abformung (LIGA) technique (mainly to avoid the use of the costly synchrotron system).

Assembly of Bending, Torsional and Extending Active Catheter Using Electroplating

This paper reports a new batch fabrication method of active catheters which have bending, torsional and extending functions for steering. The active catheter consists of shape memory alloy (SMA) coil actuators and a liner coil to return to its original shape. The SMA coil and the liner coil are connected each other using electroplating of nickel and electrodeposition of acrylic polymer. This novel method makes low cost assembly and small diameter (φ1.4mm) possible.

Effect of Deposition Conditions on the Physical Characteristics and Protective Properties of Conventional and Composition Nickel Electroplates

The results of studying physical and protective properties of nickel and nickel-based composite coatings deposited from acetate baths are shown. Empirical results are presented as polynomials of the second order and visualized by using Statgraphics.

Fabrication of Optical Wave-Guides in Silica-on-Silicon by Nickel Electroplating and Conventional Reactive Ion Etching

A novel process for the fabrication of deep optical waveguides in silica-on-silicon for optical processing applications has been developed. It makes use of nickel electroplating to conform precisely e-beam written smooth curved structures and to use the deposited nickel to etch deeply (up to 8 µm) into silica layers. It is demonstrated that nickel plating offers substantial advantages in terms of resistance and resist mold fidelity than more conventional etch masks such as patterned metal layers. The etching process, that is based on conventional fluorine reactive ion etching, has been optimized by making use of a design of experiment technique, details of process optimization and comparative analysis of different etching mask performances are also given.

Effects of Saccharin and Thiourea on Sulfur Inclusion and Coercivity of Electroplated Soft Magnetic CoNiFe Film

During the course of our recent work performed to develop an electroplated CoNiFe ternary alloy with high saturation magnetic flux density and low coercivity for use in magnetic recording heads, it was observed that two common sulfur‐containing additives, saccharin and thiourea, behave differently with respect to the dependence of sulfur inclusion and coercivity of the alloy film on the additive concentration in the plating bath. To understand the cause of this difference, scanning tunneling microscopy (STM) was performed, using Au(111) as the substrate, to examine the structure of the adsorbed layers of the additive molecules. The result revealed that the nature of adsorption is fundamentally different for the two different additives; i.e., the adsorption of saccharin is physical and reversible, whereas thiourea undergoes irreversible chemisorption. This finding is consistent with the known behaviors of the two additives in the electroplating of nickel. In this paper the different effects of saccharin and thiourea in the electrodeposition of CoNiFe alloy are interpreted based on the STM results and relevant information available in the literature on the electrodeposition of nickel. © 1999 The Electrochemical Society. All rights reserved.

Electroplating high-impact plastics

In this paper, a new technique of obtaining nickel electroplated layers on polymethylmethacrylate (PMMA) is presented. It consists of four steps.1.Conditioning. Strongly oxidizing acid mixtures are used for providing roughness on the surface by generating suitable sites for chemical bonding of subsequently applied metals.2.Nucleation. Using an acidic solution of a mixture of a palladium salt together with a tin salt it can be obtained an adsorbed film on PMMA’s surface that is reduced to metallic form.3.Electroless nickel plating. This step transforms PMMA into a conductive surface and builds up metal only to provide sufficient conductivity for electroplating. This is achieved in a classical hypophosphite electroless nickel solution.4.Nickel electroplating. Metallic microstructures are finally obtained by growing up, at the desired thickness, nickel layers on the thin electroless ones, using a standard sulphamate bath for rapid electroforming.This method of obtaining nickel electroplated microstructures was developed to replace the classical Lithographie, Galvanoformung, Abformung (LIGA) technique (mainly to avoid the use of the costly synchrotron system).

A parallel plate flow cell for the investigation of the role of surfactants in the codeposition of polymer particles in nickel electroplating

A parallel plate flow cell was designed for the study of particle codeposition in metal electrodeposition. Particle deposition was visualized and recorded with a microscope/video assembly. The effects of two surfactants (anionic sodium dodecyl sulphate and cationic cetyl trimethyl ammonium bromide) on the adhesion of anionic polystyrene particles to a nickel substrate were examined. The deposition rate in laminar flow was measured as a function of the main parameters, that is, electrode potential, Ni(ii) concentration, surfactant concentration and pH. The hydrodynamic drag force applies uniformly and tangentially to the collector under laminar flow in contrast with rotating disc or impinging jet cells. No deposition is observed unless specific attractive forces carry the particles through the boundary layer. Particle attachment takes place over a limited range of surfactant/Ni(II) composition and correlates with the formation of a surface film visible under the microscope. Results discussed are based on the adsorption of SDS and CTAB on to both the electrode and the particles, an adsorption which significantly alters the interaction potential at a short distance. The cell gives interesting evidence for the occurrence of specific interactions in electrolytic codeposition. It also proves useful for observing other phenomena, such as hydrogen bubbling.

アルミニウムアノード酸化／レーザー照射／電気めっきを用いた微細回路板の作製

Fine-pattern coils were fabricated on an insulating board using anodizing, laser irradiation, nickel deposition, insulating board sticking, and aluminum substrate dissolution. Aluminum specimens covered with porous anodic oxide films were irradiated by a pulsed Nd-YAG laser through a beam splitter, iris diaphragm, convex lens, and quartz window in a nickel electroplating solution to remove anodic oxide film. During laser irradiation, the specimen was moved 3-dimensionally with an XYZ stage by a personal computer.The width of the trench produced by film removal increased with increasing laser energy and with decreasing movement speed. After laser irradiation, nickel metal layer was electrodeposited at only the laser irradiated area by cathodic polarization. The specimen stuck on epoxy resin before dissolving the aluminum substrate. Fine pattern coils with nickel lines 15μm wide and at 25μm intervals were made on the insulating board.