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The development of protective coatings on copper alloy surfaces represents a critical research direction to enable the widespread industrial application of copper alloys. To improve the corrosion resistance and wear resistance of the copper alloy plates, a Ni-Cr-Co-based multi-principal element alloy coating was prepared via high-velocity oxygen fuel (HVOF). Then, the microstructure, corrosion resistance, and wear resistance of the Ni-Cr-Co coating and the electroplated NiCo coating were analyzed comparatively. The research results show that the phases of the Ni-Cr-Co coating contained face-centered cubic (FCC) solid solution, CrB and M23C6. The NiCo coating exhibited a single-phase FCC solid solution structure. Compared to the NiCo coating, the corrosion current density of the Ni-Cr-Co coating was reduced by 92.1% in NaF solution. A highly protective passive film was formed on the Ni-Cr-Co coating, and its low ΣCSL grain boundary proportion reached as high as 25.7%. Therefore, the Ni-Cr-Co coatings demonstrated superior corrosion resistance. The scratch wear coefficient of the Ni-Cr-Co coating was only 51.9% of that of the NiCo coating, due to the synergistic strengthening of the matrix and hard second phase. This research offers technical support and a theoretical basis foundation for the development of coatings on copper alloys with excellent corrosion resistance and wear resistance. [ABSTRACT FROM AUTHOR]

To reduce the corrosion degradation of copper alloys, an equiatomic CoCrNi medium-entropy alloy (MEA) coating was successfully fabricated on a copper alloy plate using high-velocity oxygen-fuel (HVOF) spraying. The microstructure, corrosion behaviour, and passive film characteristics of the CoCrNi MEA coating in a 3.5 wt.% NaCl solution were investigated. The CoCrNi MEA coating mainly consisted of a face-centred cubic solid solution structure and a small amount of metal oxide. Compared to that of the widely used electroplated NiCo coating, the corrosion current density of the CoCrNi MEA coating dropped by 93%. The pitting corrosion of the CoCrNi MEA coating originated from the interface between the solid solution matrix and the oxide. Due to the strong protective passive film and low coincident site lattice boundaries, the CoCrNi MEA coating exhibited superior corrosion resistance in a NaCl solution. [ABSTRACT FROM AUTHOR]

The concept of solderability is rigorously defined, accompanied by the proposal of quantitative criteria for its assessment. A comprehensive categorization of solderable materials into three distinct groups—namely, easily solderable, moderately solderable, and unsolderable—is proposed based on solderability parameters. Practical recommendations are given for the effective deployment of solderability testing methodologies across a spectrum of materials and electronic components. Detailed expositions are offered on the methods employed in the evaluation of solderability, encompassing solder immersion, measurement of solder spreading area, and assessment of capillary penetration into gaps. Schematic representations of these evaluation techniques, alongside descriptions of the requisite apparatus for their implementation, are presented. Furthermore, tabulated data on the solder spreading factors for diverse categories of chemical and electroplated coatings, including hot tinning, are given. Prolonged storage may lead to the formation of oxide films on the surface of coatings, thereby deteriorating solderability. To enhance the quality of electroplated coatings, it is recommended to employ periodic currents in nonstationary electrolysis modes during the deposition of electroplated coatings. [ABSTRACT FROM AUTHOR]

The hydrogen decrepitation of end-of-life NdFeB magnetic alloys was studied. End-of-life magnets extracted from PC hard drives were taken as a material for the experiments. The choice of these items is governed by their low cost, easy removal from PC, and small size. The magnets were demagnetized at 623 K in a medium vacuum for 4 h, which was followed by three-step cleaning of their surface to remove the electroplated coating, oxidized surface layer, and adsorbed impurities and moisture. The first step of the cleaning was sandblasting with slag shot fed at a pressure of 300 kPa. The second step was chemical etching with solutions of dilute acids (1–3% HCl, HNO3, or H2SO4 in distilled water), followed by washing in acetone. The third step was heat treatment in a vacuum, consisting in rapid heating in a shaft furnace of magnet samples placed after etching in an autoclave, with several exposures in the temperature interval 373–573 K in a medium vacuum. After these operations, the samples were quenched by placing the hot autoclave into a vessel with ice-cold water, preceded by filling the autoclave with argon. Then, alloys of the NdFeB system without removing from the autoclave were subjected to hydrogen decrepitation performed in the temperature interval from 298 to 473 K at an excess hydrogen pressure of 30 to 210 kPa to determine how these parameters influence the properties of the hydride powders obtained and the amount of hydrogen taken up. The hydrogen for the decrepitation was generated by direct desorption from the heated hydride of the LaNi5 alloy. In the pressure range 30–70 kPa and room temperature, alloys of the NdFeB system transform into hydrides. The chemical reaction with hydrogen starts instantaneously without a period of primary hydrogen adsorption. The hydride powders obtained, containing no less than 0.459 wt % hydrogen, are very brittle and can be finely milled (100-g portion) in a planetary ball mill within 6 min to obtain a powder with the particle size smaller than 20 μm. The analysis of the surface of the finely milled hydride powder particles revealed no oxygen (≤1 wt %). [ABSTRACT FROM AUTHOR]

This work deals with the development of cyanide-free copper-silver electroplated coatings on AISI-1075 steel and its corrosion behavior under a 5% NaClO solution (commercial household bleach). A cyanide-free bath based on sodium thiosulfate was employed to obtain the silver coatings using current densities from 0.2 to 5.0 mA/cm2 and different concentrations of EDTA (additive). The evolution of the open circuit potential with time showed that silver is anodic with respect to copper, so there were no intense attacks in the silver pores. Adhesion measurements were made on both coatings by the tape test. The behavior against corrosion was evaluated by polarization resistance (Rp) in samples with the best coating adhesion. The best results were obtained with a silver coating of about 20 μm in thickness deposited on copper coating previously polished with colloidal silica. The best performance was attributed to the formation of AgCl as demonstrated by x-ray diffraction and scanning electron microscopy. [ABSTRACT FROM AUTHOR]

Due to its unique physical and chemical properties, bismuth is an attractive candidate for a wide range of applications such as battery anodes, radiation shielding, and semiconductors, to name a few. This work presents the electrodeposition of mechanically stable and homogenous bismuth films at micron-scale thicknesses. A simple one-step electrodeposition process using either a pulse/reverse or direct current source yielded thick, homogenous, and mechanically stable bismuth films. Morphology, electrochemical behavior, adhesion, and mechanical stability of bismuth coatings plated with varying parameters were characterized via optical profilometry, cyclic voltammetry, electron microscopy, and tribology. Scratch testing on thick electroplated coatings (> 100 µm) revealed similar wear resistance properties between the pulse/reverse plated and direct current electroplated films. This study presents a versatile bismuth electroplating process with the possibility to replace lead in radiation shields with an inexpensive, non-toxic metal, or to make industrially relevant electrocatalytic devices. [ABSTRACT FROM AUTHOR]

In the current research work, NiMo thin films were successfully co-deposited with W on the copper substrate (NiMoW) by varying the plating times like 30, 45, and 60 min at a constant current density (50 mA/cm2). All the electroplated NiMoW thin films have been subjected to structural (SEM–EDS and XRD), mechanical (hardness, roughness, and corrosion), and magnetic (VSM) characterization analysis. The existence of a perfect nanocrystalline phase in the coated NiMoW thin films was found through XRD, and the average crystalline size varied from 33 to 37 nm. All the coated NiMoW thin films have a cubic (FCC) crystalline structure with an Fm-3m (225) space group. The obtained SEM–EDS result discloses that the synthesized NiMoW thin films have uniform surface morphology with spherically shaped nanoclusters, and the film deposited at 60 min has the maximum nickel content as compared with coatings at 30 min which in turn enhance the corrosion resistance and magnetic nature of NiMoW coatings and also reveals the NiMoW thin films coated at 30 and 45 min have almost equal W and Mo content. The thickness of synthesized NiMoW thin films was found to be varied from 5 to 15 µm using Metallurgical Microscope (OIAL/MMN/MET/01). The coatings were found to be strongly adherent with a substrate (Cu) and the NiMoW coatings at 60 min exhibited the highest hardness value of 293 VHN. The electrochemical studies of NiMoW thin films explored that the coatings synthesized at 60 min exhibited the highest corrosion resistance value of 635.18 K Ω (low corrosion rate of 0.6861 mm/year). All the electroplated NiMoW coatings have an average roughness (Ra) value of around 185 nm, and the roughness values were calculated using a profilometer. The magnetic investigation on NiMoW thin layers through VSM shows that the coatings at 60 min exhibited the nanocrystalline soft ferromagnetic nature with a lower coercivity of 106.94 Oe and saturation magnetization of 925.80 × 10–6 emu. The analysis concluded that the NiMoW thin films coated at 60 min exhibited better mechanical and magnetic properties than coatings at 30 and 45 min of deposition time. [ABSTRACT FROM AUTHOR]

Copper (Cu) has been successfully cold spray deposited on carbon fiber-reinforced polymer (CFRP) by a hybrid fabrication process. In this present study, the feasibility of Cu coating build-up on a Cu electroplated CFRP under a process with two-step gas pressures was investigated numerically and experimentally. The deformation and deposition behavior of the Cu particles on CFRPs coated with tin (Sn), nickel (Ni), and Cu were studied by comparing the single-particle impact with thick coating fabrication. The deposition efficiency (DE) of the cold-sprayed coatings was measured, and the microstructure and microhardness of the coatings were evaluated. The results showed that Cu coating build-up was possible with lower DE in the second spray pass of the cold spray system compared to that of the first fabricated cold-sprayed layer. This is due to the higher hardness of the previously cold-sprayed layer as compared to the electroplated Cu coating. Cold spray deposition of Cu on soft Sn and hard Ni interlayers was not feasible due to substrate erosion and insufficient plastic deformation of the substrate, respectively. From single particle impact deposition and thick coating fabrication, it was found that successful deposition in low-pressure cold spraying only takes place in the case of co-deformation phenomenon, where the substrate and the particle have nearly equal hardnesses. These results suggest that the relative hardness of the substrate to the particle significantly affects the particle deformation behavior and DE of the cold sprayed coating. [ABSTRACT FROM AUTHOR]

The choice of the electroplating conditions of Ni-based alloys has always been a serious research question. In this study, an artificial neural network based on central composite design modelization were used to determine the desired percentage of Ni and the optimum thickness of the coating before passing to the implementation of the work. Three main factors were found to be very important in this process; namely applied current density (I), pH of the bath and the temperature (T) during electrolysis. The optimum conditions generated by the mathematical model proposed in this work were 42 mA cm−2, pH 4.5 and 50 °C for the Ni-alloys (Zn, Co, Cr and W). Theoretically, the optimum amount of Ni and the thickness of the alloy were 40% and 23 µm, respectively. The SEM images indicated that the optimum (I) would yield homogenous and compact morphologies. Moreover, the XPS investigations revealed that the optimum pH would form a strong Ni bond. Finally, the XRD analysis showed that the optimum T would result in a stable Ni-alloy crystallinity for Zn, Co and Cr. In contrast, Ni-W alloys showed that the amorphous phases were more stable. [ABSTRACT FROM AUTHOR]

This article studies the effect of macro- and microdistribution factors on the uniformity of electroplated copper coatings in through-holes of printed circuit boards. A computer program has been developed for simulating the primary potential distribution field and for calculating the local current densities for a two-dimensional model of electrodes with arbitrary shapes and mutual arrangement. The cross-sectional profile of a through-hole with a channel width equal to the hole diameter was taken as the two-dimensional model. A calculation of the primary potential distribution field predicts that the current density in wide through-holes decreases significantly and electroplating in narrow holes is nearly blocked. As the diameter of a through-hole decreases, the macrothrowing ability decreases in accordance with the decrease in the Wagner number, while the nonuniformity of the copper deposit thickness inside the holes increases, as confirmed by micrographs of cross sections of samples obtained in the electrolyte with and without a set of additives. The latter comprised leveling agents based on polyalkylene glycols and nitrogen-containing heterocyclic compounds, along with brightening organic sulfur-containing additives. Analysis of data on the distribution of copper on the cross sections of samples treated in stagnant electrolytes and with stirring, other conditions being equal, reveals a significant effect of uneven microdistribution in narrow holes. Addition of the set of leveling and brightening compounds to the electrolyte provides a small positive leveling power, which makes it possible to obtain uniform smooth coatings without a local thickness decrease at the orifice. The noticeable increase in the copper layer thickness in the middle of narrow holes in the presence of additives observed under conditions of diffusion limitations cannot be explained solely in terms of the effect of primary and secondary distribution. The effect of the increase in d1/2 may be due to the depolarizing effect of the brightening sulfur-containing components of additives inside the holes. [ABSTRACT FROM AUTHOR]

Various methods of surface preparation for electroplating on aluminum alloys are considered. It was shown that the most suitable of them is electrochemical anodizing. The composition and operating mode of the anodizing electrolyte were developed. The effect of the electrolyte composition on the structure and the film surface development is shown. The stability of the oxide film produced as a result of anodizing to dissolution in copper and nickel plating electrolytes was demonstrated. The relationship between the adhesion of electroplated coatings to an aluminum substrate with the relief and uniformity of oxide films was established. The proposed pretreatment is universal and can be used for any aluminum alloys in modern automatic lines without breaking the technological process chain. [ABSTRACT FROM AUTHOR]

This study reports about the influence of the microstructure of electroplated Zn–Ni alloy coatings, especially the extent and characteristic of existing microcracks within, on hydrogen effusion characteristics at room temperature (RT) and 200 °C. For comparison, the behavior of an electroplated Zn coating was also investigated. The microstructures of the Zn and Zn–Ni coatings were examined by means of scanning electron microscope (SEM) and optical microscope (OM). These results were correlated with the hydrogen effusion profiles, which were determined by using a carrier gas hot extraction (CGHE) technique. In addition, a silver decoration method was applied to visualize the hydrogen effusion paths within the coatings. First both Zn–Ni electroplating processes exhibit less hydrogen absorption compared to Zn. In addition the microstructure of the Zn–Ni coatings, especially the characteristic and magnitude of the microcracks, significantly influences the hydrogen effusion characteristics. By using the silver decoration method according to (Schober in MTA 14:2440-2442, 1983) it could be proofed that for Zn–Ni hydrogen primary effuses along the microcracks and the interfaces of pustules within the coating. But the microcracks seem to promote the hydrogen effusion much more than the interfaces of the pustules. [ABSTRACT FROM AUTHOR]

The cause of the microscopic size effect in the microhardness of electroplated binary alloys between iron group metals and tungsten is identified by studying electrodeposition of Co-W alloys. The effect is caused by the presence of oxygen-containing impurities in electroplated alloys, the impurity content growing with increasing the volume current density, which leads to a reduction in the coating microhardness. We find that the nature of anodes used affects the properties of deposited coatings, in particular, microhardness, because a deposition-inducing metal complex, which is a complex of an iron group metal, is consumed during electrolysis not only at the cathode, but it may also undergo oxidation at the anode, which identifies the way the anode affects the coating properties. [ABSTRACT FROM AUTHOR]

It has been found that the electrically assisted (EA) forming can alleviate size effects due to the electroplastic effect. Size effects exist in the manufacture of tiny workpieces and severely affect material performances because the grain boundary hardening effect and strong anisotropy of the mechanical properties of the grains will lead to a strong variation in the forming properties of the sheet. In order to investigate the influences of current parameters and size effects on mechanical properties in EA forming, EA uniaxial tension tests with varying grain size and thickness were conducted on T2 red copper sheets. The small temperature rise shows the thermal effect is slight; the flow stress decreases with the increase in pulse frequency, pulse duty ratio and current density; the finer grains still result in higher strength and better plasticity; Moreover, the fluctuations of tensile strength, maximum uniform strain and fracture strain decrease with the increase in the ratio of thickness to grain size (N) at constant current density, which means pulsed current can weaken size effects. [ABSTRACT FROM AUTHOR]

In this study, I PET positron emitter was produced by 29.5 MeV protons irradiation of natural tellurium electroplated on a nickel-coated copper substrate at a current of 150.3 μA h. The routinely separation method of ion-exchange chromatography was adopted and 93% efficiency was achieved for this process. The average yield of I at the End of Bombardment (EOB) was 3.9 MBq/μA h (0.105 mCi/μA h). Additionally, the production process was simulated by the FLUKA, and the yield of 4.3 MBq/μA h (0.116 mCi/μA h) was estimated at the EOB for produced I. A reasonable agreement was achieved between the simulation results and experimental data. [ABSTRACT FROM AUTHOR]

In this paper, we propose a method to deal with the control of an electroplating line without stopping the production. The considered system is running in repetitive functioning mode, and it is modelled by a P-time event graph. The main objective is to switch the number of parallel resources to maintain a resource while the production is assumed to be always running. So, two functioning modes appears: normal and maintenance modes. Each mode is described by a state space model written in the standard algebra and a global model corresponding to a switching system which is a class of hybrid systems is obtained. Using model predictive control technique, stabilizing state feedback gains are computed over an infinite horizon respecting the time constraints while maintenance is performed. [ABSTRACT FROM AUTHOR]

The grain boundary character distribution (GBCD) of nanotwinned copper, fabricated by electroplating inside small-scale through-wafer vias, was characterized using a stereological interpretation of electron backscatter diffraction maps. The GBCD of electroplated nanotwinned copper, specified by five macroscopic parameters (three for the lattice misorientation and two for the grain boundary plane inclination), is similar to the GBCD of coarse-grained polycrystalline copper used here as a reference material. The GBCD was compared to calculated grain boundary energies determined from atomistic simulations. We find that the grain boundary population in the electroplated nanotwinned and coarse-grained reference copper is both on average inversely correlated to the grain boundary energies. The slopes of the relationships between grain boundary population and energy for the most highly populated misorientations (Σ3, Σ9, and Σ11) are different. The relationships are strongly influenced by the geometric constraints at the triple junctions and multiple twinning, which enhanced the observed frequencies of Σ9 boundaries. The results suggest that the grain boundary network and the GBCD in the polycrystalline specimens are strongly influenced by the microstructure, grain boundary energy, and multiple twining. [ABSTRACT FROM AUTHOR]

Investigations of the influence of various modes of electrolysis on the speed of processes of electrodeposition of metals are conducted. On the basis of theoretical investigations, the main potential opportunities for process intensification when using an pulsed current for processes whose speed is defined by mass transfer and charge transfer are defined. Weakly toxic electrolytes based on lactic acid are developed for formation of electroplatings by nickel, zinc, and tin; optimum parameters of stationary, galvanostatic, and potentsiostatic pulse electrolysis are determined. Investigations of kinetic regularities of the process of electrodeposition of metals are conducted, and the limiting stages of processes are defined. It is established that the greatest impact on the speed of electrodeposition of metals is exerted by potentiostatic pulse electrolysis. It is revealed that, to a greater degree, the intensification when using a pulsed current is characteristic of processes whose speed is limited by mass transfer. [ABSTRACT FROM AUTHOR]

Electroplated zinc finishes have been widely used in the packaging of electronic products for many years as a result of their excellent corrosion resistance and relatively low cost. However, the spontaneous formation of whiskers on zinc electroplated components, which are capable of resulting in electrical shorting or other damaging effects, can be highly problematic for the reliability of long-life electrical and electronic equipment. This work investigated the mechanism for whisker growth from zinc electrodeposited mild steel substrates. The incubation time for whisker growth from the surface of nodules on the surface of the electrodeposit was considerably reduced compared with that from the planar deposit surface. Recrystallisation of the as-deposited columnar structure was observed at the whisker root. This result is consistent with some recent whisker growth models based on recrystallisation. There was no evidence of iron-zinc (Fe-Zn) intermetallic formation at the iron/zinc (Fe/Zn) interface or within the zinc coating beneath the whiskers. [ABSTRACT FROM AUTHOR]

In the last several years, automobile industries have increasingly focused on galvannealed (GA) steel sheet due to their superior properties such as weldability, paintability and corrosion protection. To improve the properties further, different coatings on GA have been reported. In this context, an electroplating process (flash coating) of bright and adherent Ni plating was developed on GA steel sheet for covering the GA defects and enhancing the performances such as weldability, frictional behavior, corrosion resistance and phosphatability. For better illustration, a comparative study with bare GA steel sheet has also been carried out. The maximum electroplating current density of 700 A/m yielded higher cathode current efficiency of 95-98%. The performances showed that Ni-coated (coating time 5-7 s) GA steel sheet has better spot weldability, lower dynamic coefficient of friction (0.07 in lubrication) and three times more corrosion resistance compared to bare GA steel sheet. Plate-like crystal of phosphate coating with size of 10-25 µm was obtained on the Ni-coated GA. The main phase in the phosphate compound was identified as hopeite (63.4 wt.%) along with other phases such as spencerite (28.3 wt.%) and phosphophyllite (8.3 wt.%). [ABSTRACT FROM AUTHOR]

This paper deals with the electrodeposition of Ni-Cu-Mo ternary alloy coatings on low-carbon steel substrate from an aqueous citrate sulfate bath. The structures and microstructure of coatings were characterized by scanning electron microscopy and x-ray diffractometry. The corrosion resistance of coatings was investigated by potentiodynamic polarization (Tafel) and electrochemical impedance spectroscopy techniques. The results show that the Ni-Cu-Mo coatings are mainly composed of fcc-Ni phase and a small amount of NiCu phase. Ni-Cu-Mo coatings exhibit a nodular surface morphology, and the roughness of electroplated coating increases with the increasing of NaMoO·2HO in the bath. The corrosion performance of the coatings is significantly affected by the Mo content of the alloy coating and their surface morphology. The coating prepared in bath containing 40 g/L NaMoO·2HO has the highest corrosion resistance in 3.5 wt.% NaCl solution, while that prepared in bath containing 60 g/L (or more) NaMoO·2HO shows a lower corrosion resistance due to the presence of microcracks on the coating surface. [ABSTRACT FROM AUTHOR]

The preparation of materials with a developed surface by changing the morphology of electrolytic icosahedral small copper particles was described. At first, icosahedral small copper particles were electrodeposited from an electrolyte solution to a metal support, and then the support with the deposited metal was thermally treated and chemically etched; as a result, the specific surface area of particles and coatings significantly increased. [ABSTRACT FROM AUTHOR]

Specific features of preparation of paint-and-varnish nickel-polymer coatings by joint cathodic electrodeposition of an amine-containing oligomeric electrolyte and nickel were studied. The coatings obtained exhibit layer-by-layer heterogeneity, with the lowest layer constituted by an intermetallic compound of nickel with iron. The coatings are characterized by higher degree of cross-linking compared to the polymer coatings without nickel. A paint-and-varnish formulation based on a nickel-polymer film-forming agent was developed for electrodeposition of corrosion- and wear-resistant coatings. [ABSTRACT FROM AUTHOR]

Intense pulsed light (IPL) treatment was used for rapid thermal processing of electroplated CdTe layers, with and without CdCl. Electroplated CdTe layers consist of small grains showing highly preferential orientation along the (111) planes. IPL processing improves the crystallinity keeping the (111) preferred orientation until an energy input threshold is reached. IPL treatment beyond this point shows a sudden structural transition within the layer with a decrease in each of the orientations. The addition of a CdCl treatment prior to the IPL initiates a transition from the preferred (111) orientation to randomly oriented grains throughout the film. X-ray diffraction, scanning electron microscopy, and optical microscopy were used to study the structural and morphological changes of these films. [ABSTRACT FROM AUTHOR]

Nanocrystalline nickel (Ni) coatings were synthesized by direct current electrodeposition at current density from 1 to 30 mA/cm and pH 4. The basic composition of the bath, which was prepared by dissolving Ni metal particles in HCl, was 0.2 M Ni ions. The effects of the current density and saccharin addition on the average particle size of Ni deposits were investigated by XRD and SEM techniques. The results showed that the surface roughness decreased as the saccharin concentration increased to 2 g/l, while a further increase in saccharin concentration had no significant effect. The current density for deposition of Ni was increased as the saccharin concentration increased. The experimental results showed that the increase in the current density had a considerable effect on the average particle size of the Ni deposits. [ABSTRACT FROM AUTHOR]

The mechanical properties of metal conductor layers strongly influence the reliability of high-power electrical modules. In this study, the microstructure, elastic modulus, and residual stress during temperature cycling of screen-printed sintered paste films were evaluated to develop guidelines for designing metal conductor layers to the module. The number of pores decreased and the elastic modulus increased for paste films sintered at higher temperatures. These films deformed plastically at lower temperatures when heated from room temperature; those that had been sintered at the highest temperature of 800 °C showed the highest maximum compressive stress, which was still approximately one third smaller than that of copper electroplated films. All films developed creep deformation above 200 °C during both heating and cooling processes. The substrate under the film was considered to affect the residual stress in the elastic-deformation area owing to its coefficient of linear thermal expansion and to not affect the residual stress in the creep-deformation area. [ABSTRACT FROM AUTHOR]

Electroplating and electrochemical corrosion testing techniques are commonly used manufacturing processes for corrosion prevention and corrosion characterisation. However, the influence of electroplated coating thickness on corrosion has not received adequate attention. In this work, the effect of coating thickness on corrosion behaviour of electroplated zinc coating on copper substrate is studied. Inductively coupled plasma mass spectroscopy (ICPMS) coupled with potentiodynamic and potentiostatic polarisation measurements showed that enhanced corrosion resistance can be achieved by reducing the thickness of the zinc coating during electroplating. The increased resistance to corrosion with reduction in coating thickness is attributed to electromigration phenomenon, which is not often considered in electroplating work, but nonetheless can have significant consequences not only with regard to performance of electroplated materials but also during electrochemical analysis of corrosion. [ABSTRACT FROM AUTHOR]

This paper is the second part of the series of papers, which establishes the finite element model (FEM) of single grain cubic boron nitride (CBN) bonding for quantitative analysis and optimization of the bonding force. The FEM model of the bonding force involves the geometric modelling of the bonding couple, the determination of the mechanical properties of the electroplating layer, and the development of the algorithm for CBN grain dislodgement. By modelling the actual grain shape and bond material, the FEM model is verified through the bonding force experiments based on the inclined micro-cutting test as of part 1. Finally, the comprehensive correlation of the bonding force with the bonding layer thickness and grain orientation is established through response surface methodology. [ABSTRACT FROM AUTHOR]

Co-P films with P contents of 4.0 and 8.0 at.% were electroplated on printed circuit boards and used as surface finish of ball grid array (BGA) packages. Sn-3.0 wt% Ag-0.5 wt% Cu (SAC305) solder balls were reflowed on the Co-P finish to form SAC/Co-P solder joints. The morphology and growth of intermetallic compounds (IMCs) in SAC/Co-P joints under thermal cycling were systematically analyzed, and the effects of IMCs on shear strength and fractured surface of the joints were studied. SAC/Cu BGA solder joints were also prepared as a comparison. It was found that CoSn and (Cu, Co)Sn grew at the interface of SAC/Co-4 at.% P solder joints during thermal cycling. The shear strength of SAC/Co-4 at.% P joints exceeded that of SAC/Cu joints after 100 thermal cycles, because the granule size of (Cu, Co)Sn was smaller than that of CuSn and no Kirkendall void existed at the interface of SAC/Co-4 at.% P joints. For SAC/Co-8 at.% P joints, a layer of smooth and void-free Co-Sn-P formed at the interface, and the shear strength of SAC/Co-8 at.% P joints increased by 8.4 % in comparison with that of SAC/Cu joints after 300 cycles. In addition, the fractured surface of three kinds of joints after thermal cycling was examined. The experimental data demonstrated that Co-P surface finish enhanced the shear strength of solder joints after thermal cycling and improved the reliability of BGA packages. [ABSTRACT FROM AUTHOR]

Copper Sulphide thin films have been prepared on different substrates using electrodeposition technique. X-ray diffraction analysis showed that the prepared films possess polycrystalline in nature with cubic structure. Microstructural parameters such as crystallite size, strain and dislocation density are determined using X-ray diffraction data. Film composition and surface morphology have been analyzed using Scanning electron microscopy and Energy dispersive analysis by X-rays. Optical absorption analysis showed that the prepared films possess band gap value in the range between 2.2 and 2.4 eV for films obtained on different substrates. [ABSTRACT FROM AUTHOR]

Electroless Ni-Co-P coating and Ni-Co-P-SiO nanocomposites were successfully applied on AZ91D magnesium alloy via environmentally friendly cerium-lanthanum-permanganate treatment and their properties were compared with traditionally binary Ni-P coating. The prepared coatings were analyzed using scanning electron microscopy, x-ray diffraction, and energy dispersive x-ray spectroscopy. Moreover, the corrosion behavior of the coatings in 3.5 wt.% NaCl was evaluated by two electrochemical methods. It is found that the Ni-Co-P coating possesses more uniform and compact structure and better corrosion protection characteristics in comparison with the Ni-P coating. The plating rate of Ni-Co-P bath is relatively lower than the Ni-P bath, but it significantly increases after addition of SiO nanoparticles more probably due to adsorption of silica nanoparticles on alloy surface. The corrosion resistance of Ni-Co-P-SiO composite coatings was superior with respect to Ni-P and Ni-Co-P coatings due to formation of thick and compact coating with tortuous grain boundaries. [ABSTRACT FROM AUTHOR]

Pure Sn coatings are prepared by pulse current (PC) electrodeposition using aqueous acidic sulfate plating bath. The effects of various electroplating parameters such as current density, additive concentration, duty cycle, frequency, pH, bath temperature, and stirring rate (bath rotation) on the evolution of surface morphology of the coatings have been studied. The as-deposited coatings are characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), and surface profilometry. It is found that the current density, additive concentration, duty cycle, frequency, and pH have a major influence while temperature and stirring rate of the bath have a minor effect on the grain-size distribution. The mechanism involved in the morphology evolution and grain-size distribution due to the varying electroplating parameters has also been discussed. [ABSTRACT FROM AUTHOR]

This study focuses on the relationship between coating composition and deformation and friction behavior of zinc-iron electroplated sheet steel. The influence of phase composition and microhardness of the deposits and the electrodeposition process parameters on the mechanical properties of the material were determined. The influence of coating composition on the friction and galling behavior was also investigated. Both V-bend test and cup test were used to evaluate the influence of the iron content on the powdering and flaking behavior of the deposits. Finally, the adhesion of the coating to the substrate was studied by lap shear tests. Although the soft η phase appears to be the main component in zinc-iron coatings with less than 16 wt% Fe, Γ1 particles were observed even at low iron contents. As the iron content in the coating increases, the Γ1 fraction increases and the coating becomes harder and more brittle. Above 16 wt% Fe the deposits start to show substantial powdering and flaking during deformation. At iron contents above 30 wt%, bending of the coated product results in total coating delamination. At low iron contents, zinc-iron electroplated sheet steel exhibits a superior deformation behavior, and both cup tests and flat die tests proved the suitability of the coating for deep drawing. [ABSTRACT FROM AUTHOR]

This communication presents fluidic self-assembly of Si-chip on a sequentially electroplated multilayer solder bump with tailored transformation imprinted melting points. The multilayer solder bump is a lead free ternary solder system, which provides a route to transform the melting point of interconnects for applications in solder directed fluidic self-assembly. The outermost metal layers form a low melting point Bi33.7In66.3 solder shell (72 °C). This solder shell enables fluidic self-assembly and self-alignment of freely in water suspended Si-dies at relatively low temperature (75 °C) leading to well-ordered chip arrays. The reduction of the free surface energy of the shell-water interface provides the driving force for the self-assembly. The lowermost metal layer is a high melting point solder and acts as a core. After the self-assembly is complete, a short reflow causes the transformation of the core and the shell yielding a stable high melting point solder with adjustable melting points. The chosen ternary solder system enables the realization of interconnects with melting points in the range of 112 °C to 206 °C. [ABSTRACT FROM AUTHOR]