To apply a Cu-P composite plating film as a brazing material for Cu plates of a heat exchanger, the effect of a phosphorous particle size in the Cu-P composite plating film on brazability has been investigated. For Cu-P composite plating films using phosphorous particles with average sizes of 7.5μm and 3μm, solidus temperatures were investigated to be 765.0°C and 715.6°C, respectively. These temperatures are lower than 800°C, which is conventional brazing temperature for Cu and Cu alloys. In the case of phosphorous particle with an average size of 1.5μm, however, obvious solidus temperature was not observed by differential scanning calorimetry(DSC). In brazed Cu joints using Cu-P composite plating films with 7.5μm and 3μm size phosphorous particles, Cu phases and eutectic phases were observed. The eutectic phases consist of fine Cu and Cu3P phases. A similar microstructure was observed in a brazed Cu joint with conventional Cu-7mass%P alloy foil. In contrast, brazing was not completed when the average phosphorous particle size is 1.5μm. In the brazed interface, a brazed microstructure of Cu-7P alloy was not observed but a crack was found. In the brazed joint, phosphorus was dispersed uniformly in Cu plates. Since fine phosphorous particles can diffuse easily into Cu plates in heating process of brazing and thus the Cu-P composite film does not remain in the brazed interface, such a Cu-P composite plating film makes brazing difficult.
The surface properties of a plastic substrate were changed using a novel surface treatment called atomic hydrogen annealing (AHA). In this method, a plastic substrate was exposed to atomic hydrogen generated by cracking hydrogen molecules on heated tungsten wire. Surface roughness was increased, and O atoms and halogen elements (F and Cl) were selectively etched by AHA. The surface modification of the PEN substrate affects the surface property of the SiNx film. Adhesion between the SiNx film and the PEN substrate in the SiNx film/PEN substrate prepared by Cat-CVD shows excellent properties.
A sensitizer-activator process or a colloidal Pd/Sn process has been widely employed as the catalyst for electroless Cu plating on non-conductive substrates. The authors investigated Ag nanoparticle suspensions as a Pd-free catalyst for the electroless Cu plating. Ag nanoparticle suspensions were prepared by reducing the Ag+ ions in aqueous solutions using Sn2+ ions. The adsorption properties of the Ag nanoparticles on the glass substrates were evaluated by X-ray photoelectron spectra, atomic force microscopy examinations, and UV-vis adsorption spectra, comparing some cationic polymer electrolytes used for conditioning the substrates. It was confirmed that a large quantity of Ag nanoparticles were adsorbed homogenously onto the substrate conditioned with poly (diallyldimethylammonium) chloride. The catalytic activities for the electroless Cu plating were evaluated by the oxidation rate of HCHO. The Ag-nanoparticle adsorbed substrates showed a catalytic activity as high as that of the conventional colloidal Pd/Sn catalyst. High catalytic activity is attributed to highly dispersive adsorption of the Ag nanoparticles on a large surface area.
Wear properties of an electroless Ni-P plated A2011 alloy and polyacetal have been examined. An electroless Ni-P plated layer is an amorphous material as plated and Vickers hardness of the layer was approximately 450HV. The microstructure of the electroless Ni-P plated layer changes into crystalline structure which disperses fine Ni3P phases in a Ni matrix by heat treatment. Vickers hardness of the electroless Ni-P plated layer increases with increasing heat treatment temperature in the temperature range from 150°C to 350°C. Vickers hardness of the layer was approximately 1000HV after heat treatment at 350°C for 2h. In this study, a pin-on-disk type wear test was conducted using polyacetal and the electroless Ni-P plated A2011 alloy as pin and disk materials, respectively. From the results of wear tests, wear of polyacetal was only observed under the conditions investigated. Wear volume of polyacetal decreases with increasing Vickers hardness of the electroless Ni-P plated layer. Moreover, it was clarified that wear volume of polyacetal decreases to values lower than that using a conventional A2011 alloy with anodic oxide coating when Vickers hardness of the electroless Ni-P plated layer is over 600HV.
Copper electrodeposition from the electrolyte composed of acid copper sulfate and acetonitrile was investigated with electrochemical techniques. The current efficiency of the copper electrodeposition was measured by the rotating disk electrode, and it was found that the current efficiency decreased with the increase of the rotation rate and the decrease of current density. These results indicated that the electrodeposition with the electrolyte composed of acid copper sulfate and acetonitrile was able to fill the Vias with copper by selecting of the proper flow rate and current density.
Cross-linked tannic acid was prepared by simple operation using 1, 6-hexanediamine as a cross-linker. Then it was coated on zinc plating and its corrosion resistance was evaluated by a salt spray test. As a result, it was found that cross-linked tannic acid coating provides strong protection for zinc plating against white rust.
The structure of a coating film of tannic acid on a zinc plate was studied by infrared reflection absorption spectroscopy and quantum chemistry calculation. It was shown that the film consisted of chelate complexes of zinc(II) and tannic acid.