Electroless Ni Plating Research Articles

다이아몬드 배열 무전해 니켈 도금층/무산소동 기판의 열전도도 특성

Abstract The monolayer engineering diamond particles are aligned on the oxygen free Cu plates with electroless Niplating layer. The mean diamond particle sizes of 15, 23 and 50 µm are used as thermal conductivity pathway for fab-ricating metal/carbon multi-layer composite material systems. Interconnected void structure of irregular shaped diamondparticles allow dense electroless Ni plating layer on Cu plate and fixing them with 37-43% Ni thickness of their meandiameter. The thermal conductivity decrease with increasing measurement temperature up to 150 o C in all diamond sizeconditions. When the diamond particle size is increased from 15 µm to 50 µm (Max. 304 W/mK at room temperature)tended to increase thermal conductivity, because the volume fraction of diamond is increased inside plating layer. Keywords: Thermal conductivity, Diamond, Multi-layer materials, Electroless plating ······························································································································· ·································································································

Pretreatment and deposition process of electroless Ni plating on polyimide film for electronic field applications

The work is focused on electroless nickel plating on polyimide film. The Ni salt activation, which neglects the use of palladium, is adopted in pretreatment. The orthogonal experiment and single factor test are used to optimize the experiment, thus the optimum compositions and conditions of electroless nickel plating are obtained. The cleaned, activated and deposited polyimide films are also characterized by their structure, morphology, component and chemical state. The activation process of nickel salt is analyzed on basis of experiment and test. A Ni–P film with fine and dense structure is achieved on the polyimide film which consists of 92.23 wt.% Ni and 7.77 wt.% P. The result of tensile test indicates that the adhesion between the substrate and the coating layer is sufficiently excellent due to dimples by etching.

Effects of surface treatment on electrochemical properties of AB3.8-type hydrogen storage alloy in alkaline electrolyte

The La0.8Mg0.2Ni3.2Co0.3Mn0.1Al0.2 has been treated by the HF and KF etching solution and Ni coating solutions with the different concentrations. The surface structure and the electrochemical properties of the untreated and the treated hydrogen storage alloys have been investigated in details. The results show that the surface oxide layer on the alloys is removed after fluoridation and the surface of the alloy powders becomes smooth with electroless Ni plating. The maximum discharge capacity of the alloy electrodes is increased from 359.5 mA h g−1 (M1) to 370.1 mA h g−1 (M5) and the cycling stability is improved slightly after the surface treatment. At a discharge current density of 900 mA g−1, the high rate dischargeability (HRD) is enhanced from 38.3% (M1) to 77.0% (M5) and the M5 electrode still keeps at a high value of 55.9% at a discharge current density of 1500 mA g−1. In addition, the exchange current density I 0 and the hydrogen diffusion coefficient D are also increased by the surface treatment.

Study of the Electroless Deposition of Ni for Betavoltaic Battery Using PN Junction without Seed Layer

The method and conditions of Ni plating were optimized to maximize the output of a betavoltaic battery using radioactive 63Ni. The difference of the short circuit currents between the pre‐ and postdeposition of 63Ni on the PN junction was 90 nA at the I‐V characteristics. It is suspected that the beta rays emitted from 63Ni did not deeply penetrate into the PN junction due to a Ni seed layer with a thickness of 500 Å. To increase the penetration of the beta rays, electroless Ni plating was carried out on the PN junction without a seed layer. To establish the electroless coating conditions for 63Ni, nonradioactive Ni was deposited onto a Si wafer without flaws on the surface. This process can be applied for electroless Ni plating on a PN junction semiconductor using radioactive 63Ni in further studies.

Solid–liquid phase equilibria of Ca(H2PO2)2–CaCl2–H2O and Ca(H2PO2)2–NaH2PO2–H2O ternary systems at 298.15 K

Calcium hypophosphite has been widely used as an anti-corrosive agent, flame retardant, fertilizer, assistant for Ni electroless plating, and animal nutrition supplements. High purity calcium hypophosphite can be synthesized via the replacement reaction of sodium hypophosphite and calcium chloride. In this work, the solid–liquid phase equilibria of Ca(H2PO2)2–CaCl2–H2O and Ca(H2PO2)2 –NaH2PO2–H2O ternary systems at 298.15K were studied experimentally via the classical isothermal solubility equilibrium method, and the phase diagrams for these two systems were obtained. It was found that two solid salts of Ca(H2PO2)2 and CaCl2∙6H2O, and three solid salts of Ca(H2PO2)2, NaCa(H2PO2)3, and NaH2PO2∙H2O can form in the corresponding systems under phase-equilibrium conditions. Ca(H2PO2)2 has low solubility in the Ca(H2PO2)2–CaCl2–H2O system. NaCa(H2PO2)3 occupies a large solid field in the ternary system of Ca(H2PO2)2 –NaH2PO2–H2O.

DMAB Effects in Electroless Ni Plating for Flexible Printed Circuit Board

DMAB Effects in Electroless Ni Plating for Flexible Printed Circuit Board

A novel palladium-free surface activation process for electroless nickel deposition on micro-arc oxidation film of AZ91D Mg alloy

In this paper, a novel palladium-free and environmentally friendly surface activation process for electroless Ni plating on micro-arc oxidation (MAO) film of AZ91D Mg alloy was studied. A tight, dense and continuous structure of Ni–B/Ni–P coating was obtained on micro-arc oxidation film of AZ91D Mg alloy followed by an immersion into silver ion ink activation solution. Compared with bare AZ91D magnesium alloy, the corrosion potential of the composite coating increased by 1.2V, while the corrosion current density decreased by two orders of magnitude. Electrochemical impedance spectroscopy (EIS) results showed that the corrosion resistance of AZ91D magnesium alloy was significantly improved by the composite coating. The MAO film as an intermediate layer could reduce the galvanic corrosion between Ni and Mg substrate in 3.5wt.% NaCl solution. This novel method is a simple, acid-free and cost effective activation process for a replacement of Pd activation method in electroless plating Ni process.

An Electroless-Ag Reflector Developed for High-Brightness White LEDs

This study was conducted to investigate the reflectivity and the reflectivity stability of the electroless (Ag) metallization of reflectors used in high-brightness white GaN light-emitting diode packages. Two main reflector metallization schemes were studied: (1) electroless-Ag/electroless-pure-Pd/electroless-Ni plating and (2) electroless-Ag/electroless-Pd(P)/electroless-Ni plating. The reflectivity achieved using all reflector-metallization schemes was >85% in the visible range. However, in the electroless-Ag/electroless-pure-Pd/electroless-Ni reflector, reflectivity exhibited substantial thermal degradation; this was because of two principal factors: (1) the change in the surface morphology of the electroless-Ag surface grains; and (2) the alloying effect on the Ag layer exerted by the interdiffusion occurring with the underlying Pd layer. In this study, P was added to the Pd layer, and the thermal degradation of the annealed electroless-Ag/electroless-Pd(P)/electroless-Ni reflector was measured to be less than that of the electroless-Ag/electroless-pure-Pd/electroless-Ni reflector. The P content retarded the interdiffusion between the Ag and Pd(P) layers and preserved the faceted surface of the electroless-Ag layer, which enhanced the stability of the reflectivity of the electroless-Ag reflector. Furthermore, increasing the thickness of the electroless-Ag layer reduced the amount of Pd diffusing through the Ag layer, which helped retain the reflectivity of the Ag surface.

Black Pad Susceptibility of the Electroless Ni Films on the Cu UBM

The occurrence of black pad in the electroless Ni film during the immersion gold process is related to the surface morphology of the Ni(P) film. A nonuniform distribution of the nodule size and curvature is the crucial factor. Large nodules with small surface curvatures had higher P concentration and did not corrode, while small nodules with large surface curvatures had lower P concentration and corroded. Experiments using different types of Cu substrates suggest that the Ni(P) film black pad susceptibility increased with the defect density and/or the residual stress in the underlying substrate. Annealing the Cu substrate before the electroless Ni plating greatly reduced the black pad formation.

Characterization and Selective Properties of Electroless Deposited All Wet Contact Electrode

We report here the formation of an electrode through a selective electroless plating process. It consists of pre-treatment, selected Ni electroless plating, and Cu electroless chemical plating. Through the selective electrode formation technique using Pd/Ni/Cu, we established a high-efficiency and low-cost process for the manufacture of crystalline silicon solar cells. Measurements with a solar simulator showed that an open-circuit voltage of 0.684 V, short-circuit current density of 32.3 mA/cm2, form factor of 75.39%, and an efficiency of 18.21% was obtained for a monocrystalline silicon solar cell.

Investigation on plated Ni/Cu contact for mono-crystalline silicon solar cells

Silicon solar cells are required to be processed with low cost and high efficiency. Ag paste, which is frequently used for the front contact of commercial screen-printed solar cells, has high contact resistance and high cost. Therefore, it is necessary to develop an inexpensive metallization technique with improved cell performance. As an alternative, plated Ni/Cu contact was used to fabricate low cost and high efficiency solar cells in this paper. Ni/Cu metals have low cost, low contact resistance and high conductivity. Ni was formed for low contact resistance and barrier to plated Cu, which was the main contact for low cost and high conductivity. In particular, a plated Ni layer is a very crucial factor that determines performance of the contact for plated Ni/Cu solar cells. A plated Ni layer has a decisive effect on contact resistance, series resistance and fill factor. In this paper, Ni electroless plating conditions (deposition time and pH) were varied to form a well plated Ni layer. For an optimized Ni electroless plating condition (5 min of deposition time and 8.5 of pH), the efficiency of plated Ni/Cu contact solar cells recorded 18.68%.

무전해 니켈도금된 다중벽 탄소나노튜브의 첨가가 알루미나강화 에폭시 복합재료의 열전도도 및 파괴인성에 미치는 영향

본 연구에서는 무전해 니켈도금에 따른 탄소나노튜브의 표면특성변화가 알루미나강화 에폭시 복합재료의 열전도도 및 파괴인성에 미치는 영향에 대하여 살펴보았다. 무전해 니켈도금된 탄소나노튜브의 표면특성은 주사전자현미경(SEM), X-선 광전자분광기(XPS), X-선 회절분석(XRD)을 통하여 알아보았다. 열전도도는 열전도율 측정 시스템으로 측정하였고, 파괴인성은 만능시험기(UTM)를 이용한 임계응력세기인자(<TEX>$K_{IC}$</TEX>)를 측정하여 분석하였다. 실험결과, 무전해 니켈도금은 탄소나노튜브의 표면특성의 변화를 가져오며, 니켈도금된 MWCNTs(Ni-MWCNTs)가 들어있는 경우 미처리 MWCNTs와 비교하여 우수한 열전도도 및 파괴인성을 보였다. 이는 Ni-MWCNTs와 에폭시수지와의 분자간 상호작용의 향상 때문이라 판단된다. In this work, the effect of electroless Ni-plating of multi-walled carbon nanotubes (MWCNTs) on thermal conductivity and fracture toughness properties of MWCNTs/<TEX>$Al_2O_3$</TEX>/epoxy composites was investigated. The surface properties of the Ni-plated MWCNTs were determined by scanning electron microscopy (SEM), X-ray photoelectron spectrometry (XPS), and X-ray diffraction (XRD) analyses. Thermal conductivity was tested using a thermal conductivity measuring system. The fracture toughness of the composites was carried out through the critical stress intensity factor (<TEX>$K_{IC}$</TEX>) measurement. As a result, the electroless Ni-plated MWCNTs led to a significant change of surface characteristics of the MWCNTs. Thermal conductivity and fracture toughness of the MWCNTs/<TEX>$Al_2O_3$</TEX>/epoxy composites were greater than those of non-treated ones. These results were probably due to the improvement of intermolecular interaction between the Ni-MWCNTs and the matrix resins.

Electroless Nickel-Based Catalyst for Diffusion Limited Hydrogen Generation through Hydrolysis of Borohydride

Catalysts based on electroless nickel and bi-metallic nickel-molybdenum nanoparticles were synthesized for the hydrolysis of sodium borohydride for hydrogen generation. The catalysts were synthesized by polymer-stabilized Pd nanoparticle-catalyzation and activation of Al2O3 substrate and electroless Ni or Ni-Mo plating of the substrate for selected time lengths. Catalytic activity of the synthesized catalysts was tested for the hydrolyzation of alkaline-stabilized NaBH4 solution for hydrogen generation. The effects of electroless plating time lengths, temperature and NaBH4 concentration on hydrogen generation rates were analyzed and discussed. Compositional analysis and surface morphology were carried out for nano-metallized Al2O3 using Scanning Electron Micrographs (SEM) and Energy Dispersive X-Ray Microanalysis (EDAX). The as-plated polymer-stabilized electroless nickel catalyst plated for 10 min and unstirred in the hydrolysis reaction exhibited appreciable catalytic activity for hydrolysis of NaBH4. For a zero-order reaction assumption, activation energy of hydrogen generation using the catalyst was estimated at 104.6 kJ/mol. Suggestions are provided for further work needed prior to using the catalyst for portable hydrogen generation from aqueous alkaline-stabilized NaBH4 solution for fuel cells.

Manufacture of CNTs-Al Powder Precursors for Casting of CNTs-Al Matrix Composites

CNTs-Al matrix composites are considered to be promising heat dissipating materials because thermal conductivity can potentially be improved whilst their density is reduced. Although casting has many advantages in the fabrication of large, complex components, this process cannot be easily employed when manufacturing CNTs-Al composites. In order to produce CNTs-Al matrix composites by casting a CNTs-Al powder precursor was manufactured using mechanical milling and electroless plating processes. Aluminium powder with CNTs of 10 wt.% and 20 wt.% were mixed and ball milled using a horizontal mill. After milling for 3 hrs., the milled powder exhibits a flattened morphology with a band-type distribution of CNT clusters observed within the aluminium particles. Prolonged milling of up to 24 hrs. introduces an equiaxed particle shape for the milled powders with a uniform distribution of CNTs within the aluminium particles. However, as milling time increases, the CNTs become fractured by ball-to-ball collisions. There was no reaction evident between the aluminium and the CNTs at milling times up to 24 hrs. In order to improve the wettability between the CNTs-Al powder precursor and Al melt during the casting process, electroless Ni plating was performed. The processing time for the Ni-plating affects the uniformity of the coating layer. For a uniform coating condition, the average thickness of the coating was ~1.87 μm, with no evidence of gaps between the milled powders and coatings observed.

Surface Modification by Atmospheric Pressure DBDs Plasma: Application to Electroless Ni Plating on ABS Plates

Acrylonitrile-butadiene-styrene (ABS) plastic is a polymer material extensively used in electrical and electronic applications. Nickel (Ni) thin film was deposited on ABS by electroless plating, after its surface was treated and modified with atmospheric plasma generated by means of dielectric barrier discharges (DBDs) in air. The method in this study was developed as a pre-treatment for electroless plating using DBDs, and is a dry process featuring fewer processing steps and more environmentally friendliness than the chemical method. After ABS surfaces were modified, surface morphologies were observed using a scanning electron microscope (SEM) to check for any physical changes of the surfaces. Cross-sectional SEM images were taken to observe the binding characteristics between metallic films and ABS after metal plating. According to the SEM images, the depths of ABS by plasma are shallow compared to those modified by chemically treatment. The static contact angles were measured with deionized (DI) water droplets on the modified surfaces in order to observe for any changes in chemical activities and wettability. The surfaces modified by plasma showed smaller contact angles, and their modified states lasted longer than those modified by chemical etching. Adhesion strengths were measured using 3M tape (3M 810D standard) and by 90° peel-off tests. The peel-off test revealed the stronger adhesion of the Ni films on the plasma-modified surfaces than on the chemically modified surfaces. Thermal shock test was performed by changing the temperature drastically to see if any detachment of Ni film from ABS would occur due to the differences in thermal expansion coefficients between them. Only for the plasma-treated samples showed no separation of the Ni films from the ABS surfaces in tests. The adhesion strengths of metallic films on the ABS processed by the method developed in this study are better than those of the chemically processed films.

Roles of Cu in Pb-free solders jointed with electroless Ni(P) plating

In this study, the interfacial reaction of Sn–3.5Ag and Sn–3.0Ag–0.5Cu solders jointed with electroless Ni(P) substrate was investigated. Thick Ni3P and Ni2SnP layers formed in the Sn–3.5Ag joints because of the formation of Ni–Sn compound. In contrast, with the Cu addition in the solder, the interfacial (Cu,Ni)6Sn5 suppressed the growth of P-rich layers. However, after multiple reflows, the phase transformation occurred in the Sn–Ag–Cu joints, indicating a potential risk for crack to propagate through the dual IMC structure. To evaluate the bonding strength of solder joint, the high speed impact test was utilized to find out the weakest position among these two joints. By the comparison of the bonding energy and the X-ray fracture surface mapping between these two joints, both thick P-rich layers and dual IMC structure deteriorate the metallurgical bonding of solder joint. Eventually, the elemental cross-interaction should be considered in the final board assembled solder joints. The continuous Cu migration from the Cu metallization of board side inhibited the phase transformation on the electroless Ni(P) substrate, which might ensure the superior reliability of Cu-bearing solder joint. The roles of Cu on the interfacial reaction and mechanical strength would be addressed in the Sn–Ag–Cu/Ni(P) joints. Finally, the detailed correlation between microstructure variation and fracture failure as well as the possible mechanism was investigated and discussed.

Investigation of selective emitter in single step diffusion process for plated Ni/Cu metallization crystalline silicon solar cells

In this study, our focus is prior to the single step selective emitter for the plated Ni/Cu solar cell. Here, the light induced plating (LIP) technology is used to fabricate the Cu plated solar cell. The purpose of using electroless Ni plating is to prevent the diffusion of Cu into Si and to improve adhesion on the Si substrate as a seed layer for better electrical quality of the solar cell. The characteristics of solar cells such as short-circuit current density have also been analyzed. Throughout the experiment, we have obtained a selective emitter cell of its conversion efficiency of 17.90%, fill factor of 75.14%, VOC of 614 mV and JSC of 38.8 mA/cm2, while the conversion efficiency of 17.13%, fill factor of 73.21%, VOC of 614 mV, JSC of 38.1 mA/cm2 are obtained for a non-selective emitter Ni/Cu solar cell. The efficiency of the selective emitter cell improves about 0.77% compared to that of the reference cell.

Nickel-plated Front Contacts for Front and Rear Emitter Silicon Solar Cells

We investigate the application of nickel-plated front contacts to front and rear emitter silicon solar cells. We compare identically processed p- and n-type Si solar cells featuring (i) a homogeneous phosphorus-diffused n+ front, acting as emitter or front surface field and (ii) a full-area aluminum-alloyed p+ rear, acting as back surface field or rear emitter. This results in an n+pp+ front emitter and an n+np+ rear emitter solar cell structure, respectively. We show that the contact annealing temperature for the thermal formation of the nickel silicide (NiSix) after the electroless Ni plating has a significant influence on the NiSix layer thickness. Increasing the temperature from 300 to 450°C shifts the average thickness to higher values and augments deep NiSix spikes. The intensified penetration of the n+ front by the NiSix spikes leads to a strong degradation of the front emitter p-type Si solar cell performances due to (i) decreased shunt resistances and (ii) the contamination of the emitter space charge region. We demonstrate that the rear emitter n-type Si solar cells, in contrast, are explicitly more stable. Therefore, by applying n- instead of p-type Si as base material, an improved stability against the thermal Ni contact formation can be easily realized without significant changes in the solar cell fabrication process.

Recent Studies on Coating of some Magnesium Alloys; Anodizing, Electroless Coating and Hot Press Cladding

In the present study, coating of some magnesium alloys including AZ31 and AZ91 were studied using different techniques namely anodizing, electroless and hot press cladding. AZ91 alloy was coated using anodizing process using three types of environmental friendly electrolytes; the first based on sodium silicate, the second based on sodium hydroxide-boric acid-borax and the third on sodium silicate-potassium hydroxide-sodium carbonate-sodium tetra borate. Characterization of the anodizing layer was achieved by determination of surface morphology, microstructure, phase analysis, coat thickness, adhesion and corrosion resistance. It was found that the anodic film thickness increases with increasing the current density, anodizing voltage and deposition time until the deposition stops due to the formation of a thick anodic film. The range of the anodic film thickness is 28 42 µm.Optimization of the anodizing conditions - current density and deposition time was determined for each electrolyte. A corrosion efficiency ranging from 94% to 97% was reached; the highest value corresponding to the third electrolyte. Another study is the electroless Ni plating technique with zinc pre-treatment applied on several magnesium alloys and the effect of pre-treatment and post heat treatment on the coat characteristics. The surface morphology, surface roughness, thickness of the layer, EDX analysis, adhesion, hardness and corrosion resistance are covered in this part. The electroless layer thickness is about 6 µm. The results showed good bond quality of the coat maintaining good corrosion behaviour of electroless Ni-P based on potentiodynamic polarization tests in chloride solution where it was improved after heat treatment process. On the other hand, AZ31 was covered by a commercial pure aluminum sheet by hot pressing. The influence of the applied pressure, holding time and temperature on the bond characteristics was studied. The experimental investigation has revealed a good bond quality due to the effective mutual diffusion of Mg and Al. The phase analysis resulted in the formation of two equilibrium phases namely; Mg17Al12and Mg2Al3. The corrosion resistance of AZ31 is enhanced as a results of this process by 98.6%. Further points will be covered.Keywords: Magnesium alloys; Coating; Anodizing; Electroless; Hot press cladding; environmental friendly electrolytes; corrosion

A new electroless Ni plating procedure of iodine-treated aramid fiber

A new, durable, etchant- and tin-free catalyzation process was studied for electroless nickel metallization of aramid fiber via iodine pretreatment. Firstly, iodine components were selectively doped onto the inner part of the fiber using vapor iodine exposure followed by treatment with a tin-free acidic palladium chloride solution to form palladium iodide (PdI2) on the fiber surface. After subsequent reduction of PdI2 into metal palladium (Pd), electroless plating was carried out. A uniform Ni plating layer was formed on the fiber surface, which exhibited high durability against resistance tests of ultrasonic exposure, tape peel-off, and corrosion in NaCl solution. Here, Pd particles that formed at the inner part near the fiber surface functioned as an anchor of the plated layer as well as a catalyst of electroless plating. Investigation of the plate bath composition shows that the use of anionic surfactant enhances the adhesion of the plated layer with fiber matrix, while a reducing agent in the plate bath reduces the smoothness of the plated surface. Also, the plate bath pH and the temperature of the plating solution control the layer deposition rate noticeably more than does the plating time. The proposed method retained good tensile strength in the plated fiber. Ni-plated aramid fiber exhibited durable electrical conductivity and magnetic properties.