亮镍镀层组织中的条痕结构

在显微镜下观察亮镍镀层断面时,可见组织中有许多与基体表面平行的条痕,呈层状结构,与化学镀镍层的非晶态组织非常相似。本文从金相学角度,论述亮镍镀层中的条痕,可能是受电镀层内应力影响而形成的,从而把它与化学镀镍层区别开来。     

Determination of mechanical properties of electroplated Ni thin film using the resonance method

This paper addresses a relatively simple method of measuring the mechanical properties such as Young's modulus and residual stress of electroplated Ni thin film using the resonance method of Atomic Force Microscope. Thin layer of nickel to be measured is electroplated onto the tip side of AFM silicon cantilever and plating thicknesses were measured at the end of each plating step. The measured Young's modulus of nickel at the end of each plating step ranged from 148.04 GPa to 159.90 GPa with the maximum standard deviation of 3.47. The end deflection of electroplated AFM cantilever is also measured as a function of the plated Ni thickness, which is converted into the film stress by appropriate mechanics.     

Residual stress influence on fatigue lifetimes of electroplated AISI 4340 high strength steel

Residual stresses play an important role in the fatigue lives of structural engineering components. In the case of near surface tensile residual stresses, the initiation and propagation phases of fatigue process are accelerated; on the other hand, compressive residual stresses close to the surface may increase fatigue life. In both decorative and functional applications, chromium electroplating results in excellent wear and corrosion resistance. However, it is well known that it reduces the fatigue strength of a component. This is due to high tensile internal stresses and microcrack density. Efforts to improve hard chromium properties have increased in recent years. In this study, the effect of a nickel layer sulphamate process, as simple layer and interlayer, on fatigue strength of hard chromium electroplated AISI 4340 steel hardness – HRc 53, was analysed. The analysis was performed by rotating bending fatigue tests on AISI 4340 steel specimens with the following experimental groups: base material, hard chromium electroplated, sulphamate nickel electroplated, sulphamate nickel interlayer on hard chromium electroplated and electroless nickel interlayer on hard chromium electroplated. Results showed a decrease in fatigue strength in coated specimens and that both nickel plating interlayers were responsible for the increase in fatigue life of AISI 4340 chromium electroplated steel. The shot peening pre-treatment was efficient in reducing fatigue loss in the alternatives studied.     

Electroless and electrodeposition of nickel boron composites

It is shown that nickel boron composite coatings can be obtained by electroplating nickel from a bath containing dispersed boron particles. This deposit heated to 300°C forms Ni-Ni₃B composite. Further heating to 400°C converts it into Ni-Ni₂B composite. Mechanical properties, corrosion resistance and wear resistance Ni-Ni₂B composite are better than nickel or the electroless Ni-B composite in the as-deposited condition. The properties of heat-treated electroplated Ni-B composite are similar to that of heat-treated electroless Ni-B composites.     

化学镀Ni-P-B4C复合镀层的耐磨性

本文通过比较化学镀Ni-P-B₄C复合镀层、Ni-P-SiC复合镀层、Ni-P合金层和电镀铬层的性能,发现Ni-P-B₄C复合镀层是其中最理想的抗磨材料。试验证明:由于-B₄C微粒的硬度高于SiC微粒,并且-B₄C本身又具有较高的抗显微切削能力,所以Ni-P-B₄C复合镀层的耐磨性显着高于Ni-P-SiC复合镀层和Ni-P合金层。由于电镀硬铬层的硬度随磨擦热的升高而迅速下降,所以其耐磨性远不及Ni-P-B₄C复合镀层。      

Hardness and structural correlation for electroless Ni alloy deposits

Electroless nickel (EN) plating has received attention as a hard coating for industrial applications due to its high hardness, uniform thickness as well as excellent corrosion and wear resistance. The electroless Ni–P deposit is a supersaturated alloy in as-deposited state, and can be strengthened by precipitation of nickel phosphide crystallites with suitable heat treatments. However, the hardness of Ni–P films degrades with excessive annealing due to grain coarsening. This is the most severe barrier for electroless Ni–P deposition process from replacing chromium plating in industrial sectors. This problem is addressed in the paper by modifying the conventional electroless Ni–P bath to co-deposit tungsten to increase the hardness of the coating. Structural changes in the coating due to incorporation of tungsten are also highlighted. Deposition is done from an alkaline hypophosphite bath. Deposits with varying tungsten content are synthesized. Chemical analysis shows that tungsten incorporation reduces the phosphorus content in the deposit. Phosphorus content varied from 3 to 7 wt.% depending upon the tungsten incorporation in the deposit which in turn varied between 8 and 18 wt.%. Coatings with high tungsten content possess high hardness when compared to binary Ni–P as well as low tungsten ternary alloy deposits.     

铝基体化学镀镍对热障涂层抗热震性影响研究

研究了铝基体化学镀镍对热障涂层抗热震性能影响，结果表明，结构相同的热障涂层，基体经化学镀镍后涂层抗热震性由原来的35次剥落失效增长到200次无明显变化，这主要是因为化学镀镍层有效减缓了热障涂层和铝基体界面位置的热应力，并大幅度提高了基体的抗氧化能力，同时热震过程中镀镍层两侧界面位置的元素扩散提高了界面结合力，涂层抗热震性提高。     

Diffusion barrier properties of electroless Ni for electroless Cu using Cu plating employing hypophosphite as a reducing agent

A series of experiments have been conducted into the feasibility of a copper interconnection manufacturing scheme in which a nickel layer is employed as the patterning guide and the cushion to subsequent electroless copper deposition. It was found that with nickel as mediator and sodium hypophosphite as the reducing agent, the copper layer can be selectively deposited on Si wafers by an electroless plating process, which saves the conventional dry etching process to pattern the copper layer. Diagnostics on such copper interconnections, using Auger electron spectroscopy (AES), cross-sectional transmission electron microscopy (XTEM) and energy dispersive spectroscopy (EDS), all indicated no diffusion of the deposited copper into the underlying nickel layer after going through 350 °C, one hour heat treatment. © 1998 Kluwer Academic Publishers     

Absorber Materials for Transition-Edge Sensor X-ray Microcalorimeters

Arrays of superconducting transition-edge sensors (TES) can provide high spatial and energy resolution necessary for X-ray astronomy. High quantum efficiency and uniformity of response can be achieved with a suitable absorber material, in which absorber X-ray stopping power, heat capacity, and thermal conductivity are relevant parameters. Here we compare these parameters for bismuth and gold. We have fabricated electroplated gold, electroplated gold/electroplated bismuth, and evaporated gold/evaporated bismuth 8×8 absorber arrays and find that a correlation exists between the residual resistance ratio (RRR) and thin film microstructure. This finding indicates that we can tailor absorber material conductivity via microstructure alteration, so as to permit absorber thermalization on timescales suitable for high energy resolution X-ray microcalorimetry. We show that by incorporating absorbers possessing large grain size, including electroplated gold and electroplated gold/electroplated bismuth, into our current Mo/Au TES, devices with tunable heat capacity and energy resolution of 2.4 eV (gold) and 2.1 eV (gold/bismuth) FWHM at 5.9 keV have been fabricated. A.-D. Brown’s and S. Smith’s research was supported in part by appointments to the NASA Postdoctoral Program at NASA Goddard Space Flight Center administered by Oak Ridge Associated Universities through a contract with NASA.     

Mikrostruktur‐Untersuchungen zum Schwingungsverschleißverhalten von Nickelkomposit‐ und Ni‐P‐Schichten

Microstructural and oscillating sliding wear studies of nickel composites and electroless Ni‐P layers In many industrial applications, oscillating sliding wear leads to serious damage of construction components. To avoid this, different layers of electroplated nickel and nickel composites as well as chemically deposited nickel phosphorus layers are used and/or tested. The performance of these layers under oscillating sliding wear was characterized. Additionally microstructure characterisations took place regarding grain size, particle content and distribution as well as concerning crystallization and development of tetragonal phase nickel phosphide. These results correlate well with the Martens hardness of the layers and contribute to understand the oscillating sliding wear characteristics of the examined layers. Heat treated Ni‐P layers achieve twice the hardness of nickel dispersion layers; however, fail under oscillating sliding stress by embrittlement, cracking and debonding. On the other hand dispersion‐hardening nano composites with TiO₂ clearly exhibit a more favourable tribological behaviour. A solid content of approx. 3 vol‐% leads to dispersion and fine grain hardening effects, which cause good protection against oscillating sliding wear; thereby the Ni‐matrix remains ductile. The incorporation of very hard particles (SiC) intensifies the oscillating sliding wear process due to the abrasive effect of the particles.     

Materials Development for Auxiliary Components for Large Compact Mo/Au TES Arrays

Pursuing the feasibility of scaling conventionally-micromachined transition-edge-sensor (TES) arrays, we have undertaken a study of materials suitable for array integration. A potential limitation of increased pixel count is adequate heatsinking of each detector element to its base temperature. We describe technical approaches for heat sinking large compact TES microcalorimeter arrays and calculate the achievable heatsinking based on measured material parameters. Techniques include backside-deposited thick film copper on arrays with deep-etched wells in the substrates and electroplated gold and copper-filled micro-trenches on the substrate surface. Another limitation is the sensitivity of the thin film circuit elements to applied stress, which can arise in fabrication and mounting of arrays of increasing size. We have explored stress and deposition temperature sensitivity in our molybdenum-based bilayers. Such process parameters can impact options for array heat sinking and electrical interconnects.      

Synthesis of nickel picrate energetic film in a 3D ordered silicon microchannel plate through an in situ chemical reaction

Micro-energetic devices with energetic and functional diversity have attracted interest from scientific communities, through features such as the integration of energetic materials into micro-electro-mechanical systems (MEMS). In this study, a method for the preparation of nickel picrate energetic films on the sidewalls of a silicon microchannel plate (Si-MCP) is presented. The Si-MCP was produced by a photoelectrochemical process and a thin film of nickel (Ni) was synthesized by electroless plating of Ni on the sidewalls of the Si-MCP. The thin film of nickel picrate was successfully produced via an in situ chemical reaction method by introducing picric acid into the 3D ordered nickel/silicon microchannel plate (Ni/Si-MCP). Field emission scanning electron microscopy, Fourier transform infrared spectroscopy and nuclear magnetic resonance spectroscopy were used to study the morphological and structural properties of the thin film. The results demonstrate that picric acid reacted with Ni to form a nickel picrate thin film. Also, differential scanning calorimetry and thermogravimetric analysis were employed to characterize the thermal decomposition of the energetic film. The approach can solve the problem of integrating organic energetic materials with MEMS devices. Also, nickel picrate can release a mass of energy and gas simultaneously, which further enhances the functional diversity of MEMS devices.     

Corrosion protection of ENIG surface finishing using electrochemical methods

Four types of thin film coating were carried out on copper for electronic materials by the electroless plating method at a pH range from 3 to 9. The coating performance was evaluated by electrochemical impedance spectroscopy and potentiodynamic polarization testing in a 3.5 wt.% NaCl solution. In addition, atomic force microscopy and X-ray diffraction were also used to analyze the coating surfaces. The electrochemical behavior of the coatings was improved using the electroless nickel plating solution of pH 5. The electroless nickel/immersion gold on the copper substrate exhibited high protective efficiency, charge transfer resistance and very low porosity, indicating an increase in corrosion resistance. Atomic force microscopy and X-ray diffraction analyses confirmed the surface uniformity and the formation of the crystalline-refined NiP {1 2 2} phase at pH 5.     

钛合金镀铬工艺研究

研究了一种可行的工艺方法,在钛及钛合金表面先化学镀镍,再电镀一层铬层,能提高零件表面硬度,能改善其耐磨性,表面硬度可达到HRC 55～60.     

Deformation characteristics of an organic thin film transistor

An organic thin film transistor (OTFT) on a flexible substrate with electroplated electrodes has many advantages in the fabrication of low cost sensors, e-paper, smart cards, and flexible displays. In this study, we simulated the mechanical characteristics of an OTFT with various compressive stress conditions using COMSOL. An analysis model, which was limited to channel, source, and drain, was used to investigate deformation and internal stress concentrations. The channel length is 40 microm and the OTFT structure is a top-contact structure. The OTFT was fabricated using pentacene as a semiconducting layer and electroplated Ni as a gate electrode. The deformation characteristics of the fabricated OTFT were predicted in terms of strain and internal stress.     

化学镀Ni－P－B_4C复合镀层的耐磨性

本文通过比较化学镀Ｎｉ－Ｐ－Ｂ＿４Ｃ复合镀层、Ｎｉ－Ｐ－ＳｉＣ复合镀层、Ｎｉ－Ｐ合金层和电镀铬层的性能，发现Ｎｉ－Ｐ－Ｂ＿４Ｃ复合镀层是其中最理想的抗磨材料。试验证明：由于Ｂ＿４Ｃ微粒的硬度高于ＳｉＣ微粒，并且Ｂ＿４Ｃ本身又具有较高的抗显微切削能力，所以Ｎｉ－Ｐ－Ｂ＿４Ｃ复合镀层的耐磨性显著高于Ｎｉ－Ｐ－ＳｉＣ复合镀层和Ｎｉ－Ｐ合金层。由于电镀硬铬层的硬度随磨擦热的升高而迅速下降，所以其耐磨性远不及Ｎｉ－ＰＢ＿４Ｃ复合镀层。     

THE EFFECT OF ARTIFICIAL FATIGUE-CRACK CLOSURE ON FATIGUE-CRACK GROWTH

An investigation of the effects of artificial fatigue-crack closure on the subsequent growth of fatigue cracks, at constant range of stress-intensity factor, was carried out for the following closure materials: (i) electroplated nickel; (ii) electroless nickel; (iii) ethylcyanoacrylate (ECA) adhesive; (iv) low-melting point (LMP) solder. It was observed that (a) the wedge thickness and area of crack surface covered by the artificial-closure material and (b) the distance of the tip of the closure wedge from the crack tip (i.e. the penetration of the closure material towards the crack tip) were the main parameters controlling the reduction in the subsequent growth rate of the fatigue crack. The results suggest that if the crack thickness (opening) is completely filled with a dense wedge of artificial-closure material, the wedge becomes effectively rigid and the precise mechanical properties of the closure material will have only a secondary influence on subsequent fatigue-crack growth in comparison to (a) and (b) above. This follows from the fact that the closure material is effectively a very thin strip compressed between the rough (high friction) sides of a crack. A rigid-wedge and elastic-crack model was found to successfully predict the changes in fatigue-crack growth rate following artificial crack-closure and gave a lower bound to the measured growth rates.     

快速电沉积法制备镍基金刚石复合镀层EI北大核心CSCD

为解决镍基金刚石复合电沉积过程中普遍存在镀层沉积速率慢、镀层内应力大的问题,本工作以新型高速Ni镀液为基础,考查了镀液中去应力添加剂含量、工艺参数,以及金刚石含量对镀层内应力影响的规律,并对复合镀层的微观形貌进行了表征。优选出了可以在30A/dm2的高阴极电流密度下快速电沉积低应力镍基金刚石复合镀层的镀液组成及工艺条件。结果表明：当镀液组成为十二烷基硫酸钠0.5g/L,乙酸铵3g/L,柠檬酸三钠1.5g/L,金刚石微粒浓度30g/L;施镀条件为pH值3~4,温度50℃时,制得的复合镀层内应力最低。     

化学镀Ni-P-Sic表面抗磨材料

本文通过比较 Ni-P-SiC、Ni-P 及电镀硬铬层组织与性能,发现 Ni-P-SiC 复合镀层是其中最理想的抗磨材料。Ni-P-SiC 复合镀层由于 SiC 颗粒提高镀层硬度,细化基体组织以及 SiC 本身抗显微切削能力好,所以其耐磨性显著高于 Ni-P 层。电镀硬铬层则由于存在大量表面网状裂纹以及它的高硬度将因摩擦热温升而迅速下降,耐磨性远不及 Ni-P-Sic 表面抗磨材料。     

The effect of nickel on the strain evolution in chemical copper films

Chemical (or electroless) copper films are deposited from an electrolyte on palladium-activated insulating substrates in order to construct electrical interconnects for electronic components. These films provide the electrical contacts that are required for subsequent galvanic copper plating. As smoother substrates are required for advanced applications, achieving sufficient film adhesion becomes more difficult. Nickel, initially added to the electrolytes in order to improve deposition speed, has increasingly become important to promote good film adhesion. Film stress strongly affects film adhesion. Here we studied the effect of nickel addition on the internal strain of the film during and after electroless deposition by monitoring the strain of the Cu crystals with X-ray diffraction. Films without nickel tend to have exponential relaxation of the film strain after the deposition. For a 2000 wt. ppm Cu electrolyte, about 30 wt. ppm Ni was required in order to prevent this from occurring. Films with higher nickel content have a columnar structure with reliable and constant tensile strain during and after the electroless deposition.