Electroless Nickel Deposition Research Articles

Thin and flexible Ni-P based current collectors developed by electroless deposition for energy storage devices

A PET film metalized by electroless nickel deposition was demonstrated as thin and flexible current collector for energy storage devices. The resultant nickel-on-PET film (Ni-PET) can be used both as current collector for electrochemical capacitors and as electrode for thin film batteries. The composition of Ni-PET was characterized by EDX and XPS. The electrochemical performance of the Ni-PET current collector was similar to Ni foil but with less hydrogen evolution at low potential. The Ni-PET film exhibited better flexibility than a metallic Ni foil. Carbon nanotubes were coated on a Ni-PET substrate to form an electrochemical capacitor electrode which exhibited high chemical stability in both liquid and solid electrolytes, showing strong promise for solid energy storage devices.

Palladium catalyst synthesis through sol-gel processing for electroless nickel deposition on glass

The method of palladium catalyst synthesis by spin-coating of silicate glass with stable isopropanol sol containing the products of controllable SnCl2 hydrolysis with subsequent treatment in PdCl2 solution has been developed. It has been shown that nanostructured Sn(II) hydroxycompounds film containing trace quantity of isopropanol was formed by sol-gel process. This film had an improved continuity and enlarged thickness, smoothed down the surface of the substrate and imparted to it high reductive ability resulting in the generation of palladium nanoparticles in the increased concentration. Mean size of palladium nuclei appeared to be about 4.9nm against 6.4nm and concentration gained 4500–5000μm−2 contrary to 1700–2300μm−2 as compared with the particles formed at the use of common aqueous SnCl2 solutions in the processes of palladium activation of dielectrics for electroless nickel deposition. The increase in palladium nanoparticles concentration, improvement of their arrangement and diminution of their sizes provided the rise in palladium catalyst activity. That was revealed in the growth of the rate of nickel films electroless deposition by a factor of 4–6, the improvement of these films microstructure and adhesion to the glass, the enlargement of their thickness from 0.3 to 2.5μm. Nickel films had good adhesion to the glass and were characterized by uniform, compact and fine-grained microstructure with a majority of grains smaller than 40nm. The developed method of palladium catalyst synthesis was applied also for electroless nickel deposition on alumina ceramics and quartz.

Preparation of styrene-γ-methacryloxypropyltrimethoxysilane/Pd nanoparticles as ink for ink-jet printing technology and electroless nickel plating on glass

This paper describes the development of a silane-based Pd catalyst used as activator to replace the traditional Pd/Sn colloid for electroless nickel deposition onto a glass substrate. In this study, a styrene-co-γ-methacryloxypropyltrimethoxysilane oligomer (St-MPS) is synthesized by free radical polymerization method in acetone aqueous solution with potassium persulfate as the initiator firstly. The St-MPS oligomer can be used to reduce and stabilize Pd nanoparticles on the one hand. On the other hand, the hydrolysis and condensation reactions taking place between the silane units in St-MPS co-oligomers and glass substrate promote the adhesion of St-MPS/Pd catalyst and the subsequent nickel deposition. The adhesion strength is also demonstrated being affected by pre-heat conditions and thickness of Ni coating. Based on our results, a Ni layer with a thickness of 8.51µm is obtained after plating for 60min. The ink based on St-MPS/Pd colloids is successfully inkjet printed onto a glass substrate. The formed palladium layer is subjected to electroless nickel plating, yielding well-defined nickel pattern.

Curcit Formation on Glass Substrate Using a Titanium-Copper Oxide Catalytic Adhesion Layer for Copper Plating

Introduction Glass has characteristics such as transparency, smooth surface, chemical and thermal stability, coefficient of thermal resistance similar to silicon, high dielectric constant, electrical insulation and physical strength, deaming it an attractive substrate material for electronic devices. Examples of application are 2.5D/3D electronic device and RF module packaging. Glass can be metallized electroless plating however, problems remain, the most predominant being inadequate adhesion between glass and plated films. Using a catalytic Ti-Cu oxide adhesive layer formed on the glass, adhesion strength of 0.5 kN/m has been obtained1 ) In this study, circuit formation by semi-additive process that’s often used in the formation of fine circuit and the influence of the Ti-Cu oxide layer on post-treatment steps was investigated.Experimental Schott Co., Ltd. Tempax 50 mm × 50mm × t 0.7 mm was used as the test substrate. Circuit formation by the semi-additive process is shown in figure 1. After the circuit formation, the removal of the Ti-Cu oxide layer was accomplished by immersion in an aqueous sodium hydroxide 100 g/dm3, trisodium citrate 5 g/dm3 solution at 80 ℃ for 10 min. Electroless NiP plating was performed as a post-process to evaluate the effectiveness of the Ti-Cu oxide layer removal method.Results and Discussion Circuits of L / S = 50/50~200/200 µm and t=10 µm dimension were formed using the semi-additive process where adhesion after circuit formation was maintained. After the circuit formation, average roughness (Ra) was observed by atomic force microscopy (AFM) and elemental analysis was performed by X-ray photoelectron spectroscopy (XPS). The Ra was 6.4 nm and 14.9 %Ti was detacted prior to removal and when performing electroless NiP plating as the post-treatment, abnormal deposition occurs between the wiring patterns. On the other hand, after performing Ti-Cu oxide layer removal treatment, the Ra was 0.5 nm and 0.3%Ti detected. Abnormal deposition of electroless nickel does not occur, therefore it was possible to deposit the electroless plating selectively on the copper circuit.Conclusions L / S = 50/50 ~ 200/200 um circuits formed on a smooth glass substrate was possible.The adhesion layer of Ti-Cu oxide can be removed by an alkaline solution. By performing the Ti-Cu oxide layer removal process, abnormal deposition of electroless nickel plating in a post-treatment step can be prevented. Acknowledgments This work was funded in part by the “MEXT-supported Program for the Strategic Research Foundation at Private Universities” and the “Tokyo Ohka Foundation for the promotion of Science and Technology.” References 1)K. Okabe, T. Kagami, Y. Horiuchi, O. Takai, H. Honma, and C. E. J. Cordonier, “Copper Plating on Glass Using a Solution Processed Copper-Titanium Oxide Catalytic Adhesion Layer”, Journal of The Electrochemical Society, Vol.163, No.6, p. D201-D205, (2016) Figure 1

In Situ-Raman Spectroscopy and Comparison with DFT Computational and Experimental Study of Electroless Nickel Deposition

The kinetic mechanism of the electroless deposition of NiP from hypophosphite solutions was investigated from first principles with the intent of determining a set of elementary reactions that could effectively identify the most relevant steps of this complex process. The outcome of the computational approach is discussed in terms of experimental results obtained by electrochemical methods and surface analysis techniques [1,2]. Simulations were performed with Density Functional Theory DFT using the B3LYP exchange and correlation functionals [3], the 6-311+G(d,p) basis set for P,C,H and O atoms [4], and the Stuttgart effective core potential basis sets for Ni [5]). The interaction of Ni++ and H2PO2- with the Ni surface was studied using Ni clusters of different sizes (from 4 to 12 atoms). Solvation in water was modeled using the implicit polarizable continuum model [6]; calculations were performed using the G09 computational suite [7]. Simulations were initially devoted to the identification of the first reaction steps that lead to the adsorption of Ni++ on the Ni surface and to its successive reduction by means of the hypophosphite anion. Though several theories were proposed to describe this key step in the literature, our search was guided by the original insight published several years ago [8], according to which the reduction of Ni++ requires the formation of an intermediate species containing the NiOH group. Such species would then take active part in the transfer of the OH group to H2PO2-, thus favoring its oxidation to H2PO3-. In addition, it was imposed that the searched elementary mechanism satisfies the experimental observation, obtained with marked deuterium species, that each molecule of hydrogen that is evolved contextually to the deposition of NiP contains two H atoms coming from two H2PO2- anions. The possibility that NiOH+ is formed in solution prior to deposition was investigated determining computationally the pKa of Ni++. Results revealed that the formation of NiOH+ is not favored in the pH ranges in which NiP is usually deposited. A similar result was obtained when considering the possibility that NiOH+, after being formed in solution, is stabilized through the formation of a complex with H2PO2-. A thermodynamically favored set of reactions was instead found when it was investigated the possibility that NiOH is formed at the surface contextually with a Ni-H2PO2 complex. It was in fact found that the following set of reactions has a globally slightly negative (≈ -5 ± 5 kcal/mol) free energy change: R1) Ni ++ + surf ® Niads ++ R2) Niads ++ + 2 H2O + H2PO2 - ® NiOH(H2PO2)ads + H3O+ The minimum energy structure of the surface NiOH(H2PO2)ads species optimized at the B3LYP level on a Ni8 cluster in implicit water. The two reactions set R1-R2 provides a mechanism for the initial step of reduction of Ni++, thermodynamically viable and consistent with the hypotheses formulated above. The results of this analysis suggest therefore that the initial step of Ni++ reduction during NiP deposition involves a concerted mechanism in which adsorbed Ni++ contextually reacts with H2PO2- and a water molecule. This mechanism can be also supported by electrochemical measurements, indicating the need of OH funtionalization of the catalytic surface in order to have the reaction of hyposphite. In order to understand completely the adsorption phenomena on the electrode surface during the electroless deposition process, in situ-Raman analyses were performed. The purpose of this experimental section is to discern the different complexes adsorbed on the electrode surface while the reaction proceeds. These tests were carried out at different temperature, starting from the ambient temperature to the effective process temperature. The effect of each complexing agent dissolved into electroless NiP bath on complexes adsorbed on the electrode surface and the comparison with the DFT computational analysis will be presented.

Thin and Flexible Nickel Based Current Collectors Developed By Electroless Deposition for Energy Storage Devices

The rapid development in portable and wearable consumer electronics for recreation, fitness and medicines requires thin, light weight and flexible solid state energy storage devices to improve the user experience and safety. Among the key components for solid state energy storages, relatively little effort has been made to the development of flexible current collectors. A polyethylene terephthalate (PET) film here was metallized by a simple and inexpensive electroless nickel deposition to form thin and flexible current collector for solid state energy storage devices. The PET was etched in butylamine, followed by surface activation of reduced nickel particles by sodium borohydride. The electroless nickel was then conducted in a commercial available plating bath. The chemical composition of the developed nickel on PET (Ni-PET) current collector was characterized by EDX and XPS, which showed a high P nickel deposition. SEM images suggested an island growth during the film formation. The electrochemical characterizations showed that the Ni-PET can be used both as current collectors for electrochemical capacitors (EC) and as electrodes for batteries (Fig. 1a) in the respective potential regions. The electrochemical performance of the Ni-PET current collector was similar to that of Ni foil but with less hydrogen evolution at low potential, and the flexibility was also better than that of a metallic Ni foil. The resistance of the Ni-PET current collector almost remained the same under compression but increased under tension. Nonetheless, the shape and conductivity can be recovered when the applied force was released. The carbon nanotube was coated on the Ni-PET to form an electrochemical capacitor electrode and showed high chemical stability in both liquid and solid electrolytes (Fig. 1b), suggesting a promising application in solid energy storage devices. Figure 1

Virus-Based Metal Nanofoams As Scalable Three-Dimensional Current Collectors

In this work, we demonstrate the use of M13 virus to produce metal nanofoams that can be used as current collectors in lithium ion battery electrodes. Metal foam current collectors have been demonstrated to promote rapid electronic conduction in battery electrodes while maintaining a high active material mass fraction. An ideal three dimensional metal current collector comprises a nanofoam, with pore size on the order of one lithium diffusion distance through the active material on the timescale of one (dis)charge. In such a structure, the high specific surface area of a metal nanofoam allows deposition of large quantities of active material, while a continuous metal network embedded within the electrode provides an electronically conductive pathway. However, unlike macroscopic metal foams, metal nanofoams are not widely available because robust and scalable synthetic routes for their production are difficult to achieve. Our lab has taken steps toward this by producing metal nanofoams using M13 virus as a biological template, and showing that these materials can be used as 3D current collectors. M13 is a filamentous virus that has been used as a template for nanomaterials for both electronic and non-electronic applications. Its utility arises from its nanoscale dimensions, as well as the fact that its surface chemistry and morphological properties can be controlled genetically. To fabricate metal nanofoams, we treat the M13 virus capsid as a high aspect ratio nanoparticle and use it to assemble a template. The process uses amino acid residues at three positions on the pVIII major capsid protein: the lysine residue located at position 14 (L14), a glutamic acid fusion to the protein’s N terminus (EEAE), and a tyrosine to methionine point mutation at site 21 (Y21M). The first step in nanofoam fabrication uses glutaraldehyde to crosslink a concentrated virus solution, making use of the lysine residues exposed on the virus capsid. This facile crosslinking process results in a hydrogel. These hydrogels can be formed on a wide range of substrates, and freestanding hydrogels can be produced. The virus used for this process is genetically modified with an EEAE amino acid fusion that increases its negative surface charge. That surface charge is used to bind a palladium-based catalyst, which is then used for electroless deposition of nickel onto the hydrogel. The resulting open-cell nanofoam comprises struts that are templated onto the filamentous virus. As such, modifying the morphology of the virus particles was expected to affect the foam morphology. Because virus genes encode the amino acid sequence of the proteins forming the virus capsid, this can be done genetically. We demonstrate this control using the Y21M mutation, a point mutation shown to increase the persistence length of the virus. Using a Y21M variant as a genetically programmable control, we are able to lower the relative density of our foams. We also demonstrate control over foam morphology using virus concentration, and by controlling immersion time in the electroless bath. Lithium ion battery active materials were deposited on the nanofoam surface using electrodeposition. This technique is employed to deposit a controllable thickness of manganese oxide onto the surface of our biologically derived metal nanofoams. The resulting foams are then assembled into half cells. Using pulsed electrodeposition, the active material thickness was controlled by varying the number of pulses. By depositing thin active materials, we demonstrate that it is possible to produce ‘capacitor-like’ biotemplated electrodes with excellent rate capability. Thicker active material layers are used to produce more energy-dense electrodes with lower rate capability. Beyond the use of virus to synthesize three-dimensional current collectors for coin cells, we demonstrate that the biological templating method allows scale-up of the nanofoams to produce larger batteries. As the foams are based on self-assembling virus nanoparticles, it is possible to obtain large quantities of the template through biological amplification. Unlike a process employing extensive top-down fabrication techniques, genetically programmable templates provide a facile route toward large-format electrodes with control over nanoscale morphology. Through amplification of the virus and scale-up of the nanofoam production process, we demonstrate 4”x3” pouch cells. These electrodes are shown to be flexible, allowing compatibility with a wide range of systems. This demonstrates our biological templating method as an advance toward practical metal nanofoam engineering materials. Figure: an M13-templated nickel nanofoam before active material deposition. Figure 1

Electroless nickel deposition over the surface of bismuth telluride wafer as a barrier layer

ABSTRACTTechnology of electroless-deposition nickel on the surface of thermoelectric cooling wafer (Bi2Te3) was investigated in the paper. It consists of coarsening, removing coarsened films, reduction, sensitization, activation, pre-reduction, electroless-deposition nickel, heat treating. Bi2Te3 is attributed to catalyze poison material to the electroless-deposition nickel bath. We adopted sensitization, activation and reduction to treat wafer, then catalytic activity crystal nucleus which adsorbed the surface of Bi2Te3 may rapidly induce nickel-deposited to the whole wafer, so as to keep Bi2Te3 form poisoning bath and retarding nickel-deposited. For controlling the thickness of film, the relation between the thickness of film and how long to dispose in the plating bath was observed by tests. At the same time, the process parameters of electroless-deposition nickel bath were discussed. For the complicated working processes are simplified to make it easier to operate and maintain, simplified test processes has been investigated in the paper. Short-cut test processes: before electroless-deposited nickel on the surface of wafer, thin bismuth coating was plating, Nickel coating was obtained by the way.

Autocatalytic Ni-P and Ni-B deposition on SiC powders

Ceramic particles such as silicon carbide (SiC) have attracted great attention because of their usability as reinforcement for composite materials. Autocatalytic (electroless) nickel deposition is an excellent process for the enhancement of surface properties of ceramic particles. In this study, deposition of nickel–phosphorus (Ni-P) and nickel–boron (Ni-B) layer on SiC particles by way of autocatalytic plating in hypophosphite and borohydride baths was investigated. SiC powders were sensitised and activated respectively in order to ensure catalytic properties. Electroless nickel coating was performed from two different nickel ion sources (nickel chloride, nickel sulfate) following the pretreatments of particle surfaces. Coated powder morphologies were characterised by scanning electron microscopy. Energy-dispersive spectroscopy analysis was used to investigate the chemical analysis of coatings. The results showed that a better uniformity and bonding were obtained for Ni-P coatings with the Ni2+ source of NiSO4.6H2O as compared to NiCl2.6H2O. For Ni-B coatings, the Ni2+ source of NiCl2.6H2O has provided better quality and continuous coating layer on SiC surfaces.

Noncrystalline nickel phosphide decorated poly(vinyl alcohol-co-ethylene) nanofibrous membrane for catalytic hydrogenation of p-nitrophenol

In this work, we prepare a poly(vinyl alcohol-co-ethylene) (PVA-co-PE) nanofibrous membrane supported Ni-P nanocatalyst via a melt-phase-separated nanofiber-suspension coating followed by nickel electroless deposition with sodium hypophosphite as the reducing agent. The morphology and structure analysis show that the PVA-co-PE nanofibrous membranes (NFM) are decorated by the coating of nickel based nanoparticles on the surface of nanofibers, which is a mixture of Ni and Ni3P with about 30nm average nanoparticle size. The 3D nanofibers’ scaffold with 4.55g/m2 nanofiber coverage density (pore size: 180nm) affords a best deposited substrate for Ni-P nanoparticles to hydrogenate p-nitrophenols (PNP). The supported catalysts exhibit high catalytic rate constant 18.04×10−3s−1, 26.84×10−3s−1 and 19.40×10−3s−1 at 20°C when Ni-P loading content is 50wt.%, 25wt.% and 14wt.%, respectively. Furthermore, the catalytic materials present an excellent recoverable and cyclic feature that still over 98% conversion of PNP after 6 times. The outstanding performance obtained here can be attributed to phosphorous doped nanostructure of nickel catalyst, 3D microstructure of nanofibrous membrane and the synergistic effect of nano Ni-P and membrane, including high specific area for holding Ni-P atoms, plenty of electron holes for adsorbing organic molecules, and good conductivity for electron transfer between each decorated nanofibers. Moreover, present Ni-P-based catalyst is relatively cheap, stable and direct separable, implying its superiority in hydrogenation of nitrophenols to aminophenols.

Fabrication of A356-based rolled composites reinforced by Ni–P-coated bimodal ceramic particles

Three arrangements of reinforced A356-based composites were fabricated. Samples with 3 wt% Al2O3 (average particle size: 170 µm), 3 wt% SiC (average particle size: 15 µm), and 3 wt% of mixed Al2O3–SiC powders (each reinforcement 1.5 wt%) were fabricated. The novel fabrication process of two-step stir casting followed by rolling was utilized. Analysis of the effect of using bimodal-sized ceramic particles and process parameters on the microstructure and mechanical properties of the composites was examined. Electroless deposition of nickel was used to improve the wettability of the ceramic reinforcements by the molten metal. From microstructural characterization, it was found that fine SiC particles were agglomerated, including when coated with Ni–P. It was also revealed that the rolling process broke the fine silicon platelets within the A356 matrix, which were mostly observed around the Al2O3 particles. The processed microstructure of the composite was altered in comparison to conventionally cast A356 MMC by translocation of the fractured silicon particles, by improving the distribution of fine SiC particles, and by elimination of porosities remaining after casting. A good bonding quality at matrix–ceramic interface was formed during casting and no significant improvement was found in this regard after the rolling process. The mechanical properties of the composites tested showed that the samples, which contained the bimodal ceramic particle distribution of coarse Al2O3 and fine SiC particles produced the highest levels of composite strength and hardness.

Electroless Plating: A Versatile Technique to Deposit Coatings on Electrical Steel

Coatings on grain-oriented electrical steel (GOES) are produced primarily by roller coating deposition of aluminum orthophosphate on the top of forsterite. These coatings provide the insulation resistance and stress to improve the magnetic properties. Electroless deposition of nickel- and cobalt-based coatings could be used as an alternative, because these coatings can be made insulated and stress can be generated and tailored in these coatings. The rate of deposition in electroless plating is faster when compared with other chemical coating techniques, and the process is autocatalytic (no external current required). The coatings are corrosion resistant, and the magnetic properties of the coatings can be varied by simply changing the pH of the solution. Addition of alloying elements, such as phosphorus and boron, can manipulate the stress generated in the coating from tensile to compressive and vice versa. A $2.15\pm 0.15~\mu \text{m}$ thick Co–Ni–P coating on GOES was able to reduce the power loss by 9%–11%. Similarly, a 414 ± 40 nm thick coating of Co–P-carbon nanotube (CNT) on GOES was able to reduce the power losses ranging 13%–15%. The reduction in power loss in a Co–Ni–P coated sample was due to the tensile stress applied to GOES by the coating that reduced the anomalous loss. The surface roughness was improved for both the Co–Ni–P and Co–P-CNT coatings. An improvement in the surface roughness contributed to the reduction of hysteresis loss.

Electrochemical performance of Al–Ni/MWCNTs nanocomposite anode for Li-ion batteries: the effect of MWCNT amount

Aluminum–nickel/multiwall carbon nanotubes (Al–Ni/MWCNTs) composites have been prepared and tested as a new type of anode material. First, core–shell aluminum–nickel composite particles were fabricated using an electroless deposition of nickel onto the aluminum. Then, Al–Ni/MWCNTs composites were prepared by combining different amounts of MWCNTs (10, 20, 40 wt%) using a planetary ball milling method. The morphologies and structures of the produced Al–Ni/MWCNTs composite powders were characterized using scanning electron microscopy, and energy dispersive spectroscopy was used to understand the elemental surface composition of composites. X-ray diffraction analysis was performed to investigate the structure of the Al–Ni/MWCNTs composite powders. To investigate the electrochemical performance of Al–Ni/MWCNTs composite electrodes, charge/discharge tests and cyclic voltammetry were performed using the produced cells. The amount of MWCNTs was shown to be critical to improving the Al–Ni/MWCNTs composite anodes with respect to cyclability and stability.

Comparative study of electroless nickel film on different organic acids modified cuprammonium fabric (CF)

Nickel films were grown on citric acid (CA), malic acid (MA) and oxalic acid (OA) modified cuprammonium fabric (CF) substrates via electroless nickel deposition. The nickel films were examined using scanning electron microscopy (SEM) and X-ray diffraction (XRD). Their individual deposition rate and electromagnetic interference (EMI) shielding effectiveness (SE) were also investigated to compare the properties of electroless nickel films. SEM images illustrated that the nickel film on MA modified CF substrate was smooth and uniform, and the density of nickel nuclei was much higher. Compared with that of CA modified CF, the coverage of nickel nuclei on OA and MA modified CF substrate was very limited and the nickel particles size was too big. XRD analysis showed that the nickel films deposited on the different modified CF substrates had a structure with Ni (111) preferred orientation. All the nickel coatings via different acid modification were firmly adhered to the CF substrates, as demonstrated by an ultrasonic washing test. The result of tensile test indicated that the electroless nickel plating on CF has ability to strengthen the CF substrate while causes limited effect on tensile elongation. Moreover, the nickel film deposited on MA modified CF substrate showed more predominant in EMI SE than that deposited on CA or OA modified CF.

Synthesis and characterization of Ni–P coated hexagonal boron nitride by electroless nickel deposition

Electroless plating has been receiving a steady progress over the last decade on the modification of the surface properties of ceramic materials in order to produce composite coatings with unique characteristics for critical tribological systems. In this work, an electroless nickel deposition process was used to deposit nickel-phosphorous (Ni–P) coating on hexagonal boron nitride (h-BN) particles via hypophosphitereduced acid bath solution. The substrate particles were initially subjected to series of pre-treatment operation in order to ensure that the particles are cleaned and catalytically active prior to electroless plating. The characterization of the as-received and Ni-coated powder was studied through scanning electron microscopy (SEM), energy dispersive X-ray (EDX) spectroscopy and field emission scanning electron microscopy (FESEM). The result reveals that the pretreatment of h-BN powder provides substrate particle surfaces with coarse and roughened structures which are normally considered suitable for Ni–P deposition. Moreover, the result of the EDX analysis confirms the existence of nucleating agents and Ni–P coating on the surface of the treated h-BN powder. The cross-sectional microstructure of the coated powder shows that the h-BN particles were embedded in a continuous matrix layer of Ni–P deposit. The EDX mapping profiles further indicate that the deposited Ni–P alloy mass was uniformly distributed on the surface of the Ni–P codeposited h-BN particles (Ni–P–h-BN). The successful development of Ni coated h-BN powder will raise the potential of h-BN as a high-performance coating material.

Effect of Processing Parameters on the Protective Quality of Electroless Nickel-Phosphorus on Cast Aluminium Alloy

The effects of temperature, pH, and time variations on the protective amount and quality of electroless nickel (EN) deposition on cast aluminium alloy (CAA) substrates were studied. The temperature, pH, and plating time were varied while the surface condition of the substrate was kept constant in acid or alkaline bath. Within solution pH of 5.0–5.5 range, the best quality is obtained in acid solution pH of 5.2. At lower pH (5.0–5.1), good adhesion characterised the EN deposition. Within the range of plating solution pH of 7.0 to 11.5, the highest quantity and quality of EN deposition are obtained on CAA substrate in solution pH of 10.5. It is characterised with few pores and discontinuous metallic EN film. The quantity of EN deposition is time dependent, whereas the adhesion and brightness are not time controlled. The best fit models were developed from the trends of result data obtained from the experiments. The surface morphologies and the chemical composition of the coating were studied using the Jeol JSM-7600F field emission scanning electron microscope.

A novel Ag catalyzation process using swelling impregnation method for electroless Ni deposition on Kevlar® fiber

A novel Ag catalyzation process using swelling impregnation pretreatment method was developed for electroless nickel (EN) deposition on Kevlar fiber. Firstly, the fiber was immersed into an aqueous dimethylsulfoxide (DMSO) solution of silver nitrate to impart silver nitrate into the inner part of the fiber near the surface. Subsequently silver nitrate was reduced to metal silver nanoparticles on the fiber surface by treatment with aqueous solution of sodium borohydride. After electroless plating, a dense and homogeneous nickel coating was obtained on the fiber surface. The silver nanoparticles formed at the fiber surface functioned as a catalyst for electroless deposition as well as an anchor for the plated layer. The study also revealed that the incorporation of surfactant sodium dodecyl sulfate (SDS) in electroless nickel plating bath can enhance the adhesion strength of EN layer with the fiber surface and minimize the surface roughness of the EN coating. The Ni plated Kevlar fiber possessed excellent corrosion resistance and high tensile strength.

Nickel Electroless Plating: Adhesion Analysis for Mono-Type Crystalline Silicon Solar Cells.

The adhesion of the front electrodes to silicon substrate is the most important parameters to be optimized. Nickel silicide which is formed by sintering process using a silicon substrate improves the mechanical and electrical properties as well as act as diffusion barrier for copper. In this experiment p-type mono-crystalline czochralski (CZ) silicon wafers having resistivity of 1.5 Ω·cm were used to study one step and two step nickel electroless plating process. POCl3 diffusion process was performed to form the emitter with the sheet resistance of 70 ohm/sq. The Six, layer was set down as an antireflection coating (ARC) layer at emitter surface by plasma enhanced chemical vapor deposition (PECVD) process. Laser ablation process was used to open SiNx passivation layer locally for the formation of the front electrodes. Nickel was deposited by electroless plating process by one step and two step nickel electroless deposition process. The two step nickel plating was performed by applying a second nickel deposition step subsequent to the first sintering process. Furthermore, the adhesion analysis for both one step and two steps process was conducted using peel force tester (universal testing machine, H5KT) after depositing Cu contact by light induced plating (LIP).

Effect of Polishing Grits, Temperatures and Selected Activators on Electroless-nickel Deposition on Cast Aluminium Substrates

The state of the surface of a material controls how stable and lasting such material will be under the service condition.Wear and corrosion take palce on the contacting surfaces.For an efficient engineering design,the surface has to be protected by different method of serface deposition technique such as electroless-nickel(EN) plating . The firmness and the dependability is built stronly on the morphology of the metallic film. The paper aimed to study the effect of grinding grits,types of activator and planting operation temperatures.....

Catalytic role of surface pre-treatment of noble-metal-like tungsten carbide powder on electroless deposition of nickel

In this paper, tungsten carbide (WC) powder without noble-metal activation pretreatment has been coated with a thick layer of nickel (Ni) particles by ultrasonic-assisted electroless plating process at room temperature. The surface morphologies and composition of original WC powder, pretreated WC powder, Ni-coated WC powder prepared in different electroless nickel plating (ENP) baths and worn WC–Ni composite powder were analyzed by field emission scanning electron microscopy (FE-SEM) and energy dispersion spectrometry (EDS). The results suggest that the initial WC powder, whether or not pretreatment, are both able to initiate ENP successfully. WC itself is considered to have noble-metal-like catalytic performance to induce ENP under the system of sodium hypophosphite as reducing agent. The surface defects created by specific chemical activation pretreatment not only effectively enhance the catalytic ability, but also improve binding force of WC substrate and Ni coating. Moreover, the composition of ENP bath is a key factor which can regulate the growth rate and adsorption rate of Ni particles to maximize the catalytic activity of WC powder.