Wet Plating Research Articles

Real-Time Thickness Measurement of Marine Oil Spill by Fiber-Optic Surface Plasmon Resonance Sensors

Rapid detection of marine oil spills is becoming increasingly critical in the face of frequent marine oil spills. Oil slick thickness measurement is critical in the hazard assessment of such oil leaks. As surface plasmon resonance (SPR) sensors are sensitive to slight changes in refractive index, they can monitor offshore oil spills arising from significant differences in the refractive index between oil and water. This study presents a gold-film fiber-optic surface plasmon resonance (FOSPR) sensor prepared by polydopamine accelerated wet chemical plating for rapid and real-time measurement of oil slick thickness. We examined oil thickness detection at two interfaces, namely, water-oil and air-oil. Detection sensitivity of −1.373%/mm is obtained at the water-oil interface in the thickness range of 0–5 mm; detection sensitivity of −2.742%/mm is obtained at the air-oil interface in the thickness range of 0–10 mm. Temperature and salinity present negligible effects on the oil slick thickness measurement. The fabricated FOSPR sensor has the ability to detect the presence of oil as well as quantify the oil thickness. It has favorable repeatability and reusability, demonstrating the significant potential for use in the estimation of marine oil slick thickness.

Fabrication of WC-Ni Composite Hard Coatings by Wet Plating and Gas Carburizing Complex Method and Evaluation of Its Mechanical Properties

Fabrication of WC-Ni Composite Hard Coatings by Wet Plating and Gas Carburizing Complex Method and Evaluation of Its Mechanical Properties

Cu metallisation on glass substrate with through glass via using wet plating process

ABSTRACT The IoT (Internet of Things) society will be arriving in the near future, and many things will be connected by the Internet. Consequently, data traffic will be increased, and so will the demand to improve the performance of communication devices. Currently, plastics and ceramics are commonly used as insulating materials for communication components, but they are getting close to the limit in terms of material properties, because the next generation high-performance communication devices require signal frequency of 20 GHz and beyond. Therefore, further improvements in the properties of the insulating materials as well as in the performance of electronic devices are being demanded. A glass substrate with copper film provides more advantages for electronics devices than other materials. The most obvious advantage is given by the material properties, surface smoothness, dimensional stability in high temperature, low conductivity, low dielectric loss and for its scalability to larger area panels with low cost. In the present study, the authors report on an adhesion strength of 0.4 kN m−1 between glass and copper seed layer. Moreover, a wet plating process has been successfully demonstrated which enables easy and uniform film formation on a glass wafer and inside through holes.

Method for estimating inoculum of the soilborne fungal pathogen Verticillium dahliae in Australian cotton soils

The ability to quantify inoculum levels of the soilborne fungal pathogen Verticillium dahliae in field soil is essential for understanding potential disease pressure of Verticillium wilt in cotton and for making informed management decisions. Several semi-selective media and techniques for pathogen isolation have been developed for determining the inoculum levels of V. dahliae present in soil. The objective of this study was to gather data on soil plating techniques, media, sampling depths, and times of sampling for the detection and quantification of V. dahliae in field soils, in order to develop a V. dahliae isolation protocol for Australian cotton-growing soils. Two soil plating techniques (dilution plating or ‘wet plating’, and direct spreading by hand or ‘dry plating’) on four semi-selective media (Sorenson’s NP-10, potato dextrose agar, and acidified versions of each) were compared for their efficacy in quantifying soil inoculum as germinated microsclerotia propagules per gram soil. Soil was sampled from three depths to examine the vertical distribution of the fungus and so determine the ideal sampling depth. Field soil sampling was conducted pre-planting and post-harvest to examine differences in inoculum with sampling time. Based on the results of this study, a soil sampling protocol has been developed for Australian cotton farms that includes sampling soil before planting, at a depth of 2–24 cm, and using the direct dry plating method on Sorenson’s NP-10 media.

Friction and Wear of Ni-P Electroless Plating By Adding for WO3 Particles

Electroless Ni (nickel) plating is known as an industrially unique wet plating. In particular, nickel plating is widely used for precision mechanical parts, pipes, bearings, cylinders, etc. due to its corrosion resistance, excellent hardness, and uniform plating properties. However, depending on the use environment, due to the low thermal stability, the grain growth and recrystallization of the plating layer reduce the corrosion prevention properties. For the purpose of improving thermal stability, elements such as W (Tungsten) and Mo (Molybdenum) can be added to improve mechanical properties. The composite plating containing W shows excellent heat resistance, and hardness and abrasion resistance can be improved. In addition, there is a trend to study composite plating of PTFE (Polytetrafluoroethylene) and MoS2 (Molybdenum disulfide) to improve lubricity and non-adhesion. In this study, Ni-P-PTFE-WO3 was plated using WO3 (Tungsten trioxide) powder to improve thermal stability, abrasion resistance, and lubricity. The experiment was plated at 90 ° C for 1 hour in the plating solution, and the heat treatment process was performed at 300 ° C for 1 hour. We analyzed the change in crystallinity before and after heat treatment using XRD (X-ray Diffraction), and observed the plating thickness and surface using SEM (Scanning Electron Microscope). By using wear test, the change of abrasion resistance and lubricity with and without WO3 plating will be compared.

Plasma Oxidation Printing into DLC and Graphite for Surface Functionalization

A diamond-like carbon (DLC) film, coated on a AISI420-J2 stainless steel substrate and vertically aligned graphite (VAG), was structured by high-density plasma oxidation to work as a DLC-punch for micro-stamping and DLC-nozzle array for micro-dispensing, in addition to acting as a copper-plated thermal spreader, respectively. Thick DLC films were micro-patterned by maskless lithography and directly plasma-etched to remove the unmasked regions. Thick VAG (Ca plates were micro-patterned by screen-printing and selectively etched to activate the surface. Raman spectroscopy as well as electric resistivity measurement proved that there was no degradation of VAG by this surface activation. Wet plating was utilized to prove that copper wettability was improved by this surface treatment.

Study on Aging Effect of Adhesion Strength Between Polyimide Film and Copper Layer

This paper experimentally confirmed that the adhesion strength of the copper layer formed on the surface of the polyimide film by wet plating greatly changes with the aging time. The adhesion strength of the copper layer showed a rapid increase from 4 to 10 h after aging had begun and then converged to a value without a significant change. The adhesion enhancement between polyimide film and copper layer by aging is due to the interlocking effect caused by the volume expansion of copper oxide (CuO) formed in the polyimide, the increased mobility of copper particles enlarged by the decrease of impurities in the copper layer grain boundaries, and the consequent change of the crystal structure of the copper layer leading to the internal stress reduction. Such adhesion improvement can be confirmed by the progress of the cohesive failure indicating the breakdown of the polyimide film.

Formation mechanism of tungsten carbide hard thin film by wet plating and vacuum gas carburizing complex method

Formation mechanism of tungsten carbide hard thin film by wet plating and vacuum gas carburizing complex method

Direct copper metallization on TGV (Thru-Glass-Via) for high performance glass substrate

Abstract IoT (Internet of things) society will be coming in the near future, and everything will be connected by the Internet. Consequently, data traffic will be increased, and so will the demand to improve the performance of communication devices. Currently, plastics and ceramics are commonly used as insulating materials for communication components, but they are getting close to the limit in terms of material properties, because the next generation high performance communication devices require signal frequency of 20GHz and beyond. Therefore, further improvements in the properties of the insulating materials as well as in the performance of electronic devices are being demanded. Copper conformal metallization on glass provides many opportunities for high frequency electronic devices. The most obvious advantage is given by the material properties. The glass substrate was chosen for low conductivity and low dielectric loss for high frequency application, and for its scalability to the larger area panels with low cost. While applications require strong interfacial adhesion between copper film and glass substrate, glass is often inferior as compared to metal-to metal adhesion. Direct copper metallization on glass is conventionally a difficult task, and it usually does not provide enough peeling strength either. Therefore, forming Ni and Ti seed layers by sputtering and precursors deposited by sol-gel method are being studied. However, these processes have been limitedly used or not been used in mass production, because creation of vias and simultaneous formation of seed layers on both sides by sputtering is difficult to undertake. The Sol-gel method does not provide stable peel strength and it takes a long process. This additional process requirement to add a layer to promote the adhesion of Cu to glass burdens the factories in a couple of ways: 1) enlarging the glass substrate is difficult due to the limitation in equipment size, 2) forming the film inside the through holes is also difficult due to high-aspect ratio via requirements, and 3) high cost due to slow processing speed. In an earlier reports, we presented evidence that we have successfully demonstrated direct copper plating on glass, showing the adhesion strength of 0.42kN/m between glass and copper seed layer. In the present work, we are reporting wet plating process which enables easy and uniform film formation on large glass substrates and inside through holes. This low cost wet plating process enables forming copper film directly on glass without adhesion layer and enhancing the adhesion strength without degrading glass properties and copper conductivity.

Composite Fiber by Wet Plating Process

Composite Fiber by Wet Plating Process

Fully Monolithically Fabricated Si One-Chip Miniature Fuel Cell -Electrolyte Polymerization in Porous Si Layer

A novel electrolyte layer formation for miniature fuel cells was proposed. Polymerization of electrolyte monomer was attempted in a porous Si layer. We have been developing a miniature fuel cell with MEMS techniques, and our prototype fuel cells with monolithically fabricated Si electrodes showed relatively good performance among miniature fuel cells[1]. However, adhesion between the Si electrodes and electrolyte membranes (PEM) was problematic, and poor adhesion causes lower performance. Besides, adhesion process of the electrodes and PEM is not suitable to MEMS process. Therefore, more monolithic structure is desired. Then, we have proposed a one-chip miniature fuel cell as shown in figure 1[2]. The one-chip fuel cell has a through porous Si layer, which is formed by anodization in HF solution, and the porous Si area is expected to work as a electrolyte layer. On both side of the through chip porous Si layer, catalyst layer is formed by wet plating technique. Some reports said porous Si showed ion conductivity, but the conductivity was too small for the fuel cell electrolyte layer, and electrolyte filling into the porous Si layer is needed. In some studies, polymer solution was immersed into the porous Si layer, but the performance of the obtained layer seems limited due to shrinkage of the electrolyte polymer. In this study, we attempted to fill electrolyte into the porous Si layer by electrolyte monomer polymerization in the porous Si. Viscosity of monomer solution was low, and easy penetration of the solution into the porous Si layer was expected. Then, the electrolyte monomer is polymerized and the packed polymer electrolyte layer is formed in the porous Si area. Experimental The through chip porous Si layer, which was formed by anodization in HF solution, showed independent straight pores with no connection to neighbor pores. The diameter of the pore was 40-70nm. After the porous layer formation, to raise hydrophilicity of porous Si surface for the easier penetration of the monomer solution, slight thermal oxidation (673 K for 10 min) was performed. 2-Acrylamido-2-methylpropane sulfonic acid (AMPS), which is a typical monomer containing sulfonic acid group, was chosen as the monomer. The AMPS solution was filled into the porous Si, and polymerization was performed by heating the chip. The monomer filling process was performed in nitrogen atmosphere at 275 K to prevent irregular polymerization. After 6 h immersion of the chip into the monomer solution, the chip was heated to 333 K in an oven for 6 h. Results After the polymerization, the chip was cleaved and the cross-section was analyzed as shown in figure 3. Uniform sulfur distribution, which is the component of the electrolyte, was observed in the porous Si region. A high magnification SEM image with low acceleration voltage in figure 4 showed that polymer was successfully formed in the pores. Crossover of hydrogen gas was also reduced to 1/600 by the electrolyte filling. But the crossover is still large, and further optimization will be performed.

湿式めっき法によるWC-NI系硬質薄膜形成および機械的特性評価

Tungsten carbide (WC) has high hardness and wear resistance, and powder metallurgy method is applied to form products together with metallic powder, e.g. cobalt (Co), because its formativeness is poor. Recently, application of WC by coating forms has been watched from viewpoints of reduction of tungsten (W) / Co usage and arbitrarily of products design. The purpose of this study is establishment of brand-new formation process for WC-Ni hard coating materials, which is based on wet plating and is constructed with both carbon supplying and diffusion heat treatment. In the current report, influences of both the procedure of carbon supplying and the condition of heat treatment for microstructure of the coating were discussed. In addition, hardness of the film was evaluated by using a instrumented hardness tester.

湿式めっき法によるWC-Ni系薄膜形成及び機械的特性評価

湿式めっき法によるWC-Ni系薄膜形成及び機械的特性評価

Effect of Electrolysis Condition on Internal Stress and Hardness of Ni-W Electrodeposits

Chromium plating has widely used as a surface treatment method, which has high wear resistance, hardness, and corrosion resistance. There are restrictions on the hard chromium plating to cause environmental pollution. The need to develop a wet plating method to replace this situation is being raised. Ni-W alloy plating has been reported to exhibit high hardness, wear resistance, excellent corrosion resistance and high-temperature stability, such as catching a Chrome plating by a wet plating method to replace. For the precipitation mechanism and the plating solution of this Ni-W alloy plating research, it has long been carried out by many researchers. Ni-W alloy plating has recognized as Induced Co-deposition alloy. It reported that Ni-W alloy plating is amorphous and shows a tendency to decrease of the crystal grains as the W content is increased in the coating layer, the hardness increases due to the decrease of the crystal. In this study, mechanical property of Ni-W electrodeposits in various manufacturing condition such as temperature and current density was investigated to understand the effect of electrolysis temperature and current density on internal stress and Hardness. The overvoltage strength and thermal strength explained the results.

Pd-Pt Catalyst Layer Formation Based on Porous Si

Our group proposed a Si based miniature fuel cell that has both fuel channel and catalyst layer on a Si substrate[1]. Maximum power density reached 500 mW/cm2 at 313 K with H2-O2 supply, which is comparable to conventional state-of-the-art fuel cells. In the fabrication process, initially porous Si is formed by anodization in a HF solution, then the Si is replaced by Pt in a wet plating process, and a porous Pt catalyst layer is formed on a Si chip. The catalyst layer consists of Pt, and amount Pt is estimated to be 3.6 mg/cm2, while typical conventional fuel cells use only 0.1 mg/cm2. We have to reduce the amount of Pt for practical use of the miniature fuel cell. We found that porous Pd layer can be also made with almost identical process to the porous Pt formation, and have discussed Pd-Pt catalyst for reduction of the Pt usage in our miniature fuel cells. In this study, slight Pt was deposited on the porous Pd, and prototype fuel cells showed increase of power output by only 0.01mg/cm2Pt deposition. Furthermore, the Pd-Pt catalyst showed promissing result to CO poisoning. [1] M. Hayase, T. Fujii, J. G. A. Brito-Neto, J . Electrochem . Soc ., 158(4), B355-359 (2011)

Threshold microsclerotial inoculum for cotton verticillium wilt determined through wet-sieving and real-time quantitative PCR.

Quantification of Verticillium dahliae microsclerotia is an important component of wilt management on a range of crops. Estimation of microsclerotia by dry or wet sieving and plating of soil samples on semiselective medium is a commonly used technique but this method is resource-intensive. We developed a new molecular quantification method based on Synergy Brands (SYBR) Green real-time quantitative polymerase chain reaction of wet-sieving samples (wet-sieving qPCR). This method can detect V. dahliae microsclerotia as low as 0.5 CFU g(-1) of soil. There was a high correlation (r=0.98) between the estimates of conventional plating analysis and the new wet-sieving qPCR method for 40 soil samples. To estimate the inoculum threshold for cotton wilt, >400 soil samples were taken from the rhizosphere of individual plants with or without visual wilt symptoms in experimental and commercial cotton fields at the boll-forming stage. Wilt inoculum was estimated using the wet-sieving qPCR method and related to wilt development. The estimated inoculum threshold varied with cultivar, ranging from 4.0 and 7.0 CFU g(-1) of soil for susceptible and resistant cultivars, respectively. In addition, there was an overall relationship of wilt incidence with inoculum density across 31 commercial fields where a single composite soil sample was taken at each field, with an estimated inoculum threshold of 11 CFU g(-1) of soil. These results suggest that wilt risk can be predicted from the estimated soil inoculum density using the new wet-sieving qPCR method. We recommend the use of 4.0 and 7.0 CFU g(-1) as an inoculum threshold on susceptible and resistant cultivars, respectively, in practical risk prediction schemes.

423 湿式めっき法によるWC-Ni系薄膜形成及び機械的特性評価

423 湿式めっき法によるWC-Ni系薄膜形成及び機械的特性評価

Miniature Fuel Cell with Monolithically Fabricated Si Electrodes- Pd-Pt Catalyst by Upd-Slrr

Miniature fuel cells get a lot of attention for mobile devices. Recently, our group proposed a Si based fuel cell that has both fuel channel and catalyst layer on a Si substrate[1]. Recently, maximum power density reached 480 mW/cm2 at 313 K with H2-O2 supply, and it is one of the best performances among MEMS fuel cells. However porous Pt was used as a catalyst and the Pt usage was quite high. Estimated usage was 3.6 mg/cm2, while typical Pt usage in conventional fuel cells is only 0.1 mg/cm2.We have discussed Pd-Pt catalyst for reduction of the Pt usage in our miniature fuel cells, and reported about a novel porous Pd-Pt catalyst for our miniature fuel cells[2]. In the study, initially porous Si was formed by anodization in a HF solution, then the Si was replaced by Pd in a wet plating process. On the obtained porous Pd, Pt was deposited using UPD-SLRR technique[3-4] as shown in figure 1. Large reduction of Pt amount was expected, but evaluation of the Pd-Pt catalyst was very preliminary.In this study, using the Pd-Pt catalyst formed by the UPD-SLRR technique, prototype fuel cells were made and the performance was evaluated. Experimental Miniature fuel cells were prepared using almost identical process to the previously reported one [1], in which after catalyst formation fuel channels were opened by plasma etching and monolithically fabricated Si electrodes were made. In the catalyst formation process, following process was used.The silicon wafers used in this work were N-type (Resistivity 0.004-0.006 Ohm-cm), (100) oriented, double side mirror polished 100 um thick ones. Process condition for the porous Pd formation was reported elsewhere [2].Cu UPD was performed on the porous Pd chip in a solution of 0.1M H2SO4 and 0.1M CuSO4. The electrolyte solution was deaerated for 30 minutes with N2 gas and the whole vessel for the UPD was filled with N2 during the experiment. In the UPD process, Cu wire was used as the reference electrode, and 50 mV versus Cu reference electrode was applied to the porous Pd electrode chip. Then, the porous Pd chip was moved to a Pt plating bath for the replacement of UPD Cu to Pt. Since a replacement reaction of Pd to Pt occurs automatically in a Pt plating bath, the electrode potential of porous Pd layer was shifted to cathodic side, and a specimen chip was immersed in the 2mM Pt plating bath for two minutes.A thin gold film was deposited by sputtering on the edge of the catalyst layer to have electrical contact to the low resistive Si substrate, because direct electrical contact between the porous catalyst layer and Si substrate is poor. Then, two Si electrodes are hot-pressed onto either side of PEM sheets. Results Figure 2 shows the typical EDS elemental analyses. A red line shows the spectrum after the Cu UPD, and blue line shows the spectrum after the SLRR reaction. The spectra were normalized with Pd maximum peaks. It was assumed that the expected reaction was realized. Pt/Pd weight ratio of the porous Pd-Pt catalyst was analyzed by ICP-AES and was estimated to be 0.41%, which means only 6 μg/cm2 of Pt in the prototype cells. Catalyst activity was examined by using the porous layer as a cathode catalyst. Figure 3 shows the polarization curve of the prototype cells. The Pd catalyst showed poor performance (black), while significant improvement was observed with the Pd-Pt catalyst (green). Compared to the Pt catalyst, potential drop in the low current zone was observed, and it may be due to partial Pt coverage on the Pd layer.

A miniature fuel cell with monolithically fabricated Si electrodes – Reduction of residual porous Si on catalyst layer

Higher performance was obtained in our miniature fuel cells by reducing the residual porous Si on catalyst layers. We have developed a miniature polymer electrolyte fuel cell by forming monolithic Si electrodes with MEMS techniques, in which a catalyst layer was synthesized on a Si chip by modifying porous Si to porous Pt by a wet plating process. As a result of technical limitations in the fabrication process, porous Si was left on the porous Pt catalyst layer. The residual porous Si was intended to lower the fuel cell performance by blocking reactant gas supply, and the effect of the residual porous Si on fuel cell performance was studied. The anodization conditions for porous Si formation were varied, and several prototype fuel cells were prepared with residual porous Si of different thickness. It was confirmed that a thick residual porous Si layer reduced cell performance, and high power density comparable to conventional large scale fuel cells was obtained with the least residual porous Si.

Role of Copper Oxides in Contact Killing of Bacteria

The potential of metallic copper as an intrinsically antibacterial material is gaining increasing attention in the face of growing antibiotics resistance of bacteria. However, the mechanism of the so-called "contact killing" of bacteria by copper surfaces is poorly understood and requires further investigation. In particular, the influences of bacteria-metal interaction, media composition, and copper surface chemistry on contact killing are not fully understood. In this study, copper oxide formation on copper during standard antimicrobial testing was measured in situ by spectroscopic ellipsometry. In parallel, contact killing under these conditions was assessed with bacteria in phosphate buffered saline (PBS) or Tris-Cl. For comparison, defined Cu2O and CuO layers were thermally generated and characterized by grazing incidence X-ray diffraction. The antibacterial properties of these copper oxides were tested under the conditions used above. Finally, copper ion release was recorded for both buffer systems by inductively coupled plasma atomic absorption spectroscopy, and exposed copper samples were analyzed for topographical surface alterations. It was found that there was a fairly even growth of CuO under wet plating conditions, reaching 4-10 nm in 300 min, but no measurable Cu2O was formed during this time. CuO was found to significantly inhibit contact killing, compared to pure copper. In contrast, thermally generated Cu2O was essentially as effective in contact killing as pure copper. Copper ion release from the different surfaces roughly correlated with their antibacterial efficacy and was highest for pure copper, followed by Cu2O and CuO. Tris-Cl induced a 10-50-fold faster copper ion release compared to PBS. Since the Cu2O that primarily forms on copper under ambient conditions is as active in contact killing as pure copper, antimicrobial objects will retain their antimicrobial properties even after oxide formation.