Laser-enhanced electroless plating has been a forcus of interest as a maskless selective plating technique. This study was designed to elucidate the optimum conditions under which a uniform electroless nickel film could be obtained under irradiation by an argon ion laser. Highly selective metal spots were observed in the region of laser irradiation on polyimide film activated by palladium. The amount of deposits was roughly proportional to irradiation time, and the deposition rate was approximately 4 times higher than in conventional electroless nickel plating. Electroless nickel plating without the activation process was possible selectively at the site of laser irradiation, but the films deposited were not uniform. The deposition rate during laser beam irradiation depended on the pH of the plating solution, as in conventional electroless nickel plating. Using unactivated substrates, virtually no deposits were observed when pH was less than 5. Generally the plating spots were of the same size as the laser beam, but when laser power was reduced, the plating spots were smaller than the diameter of beam. Laser irradiation also had an influence on deposit structure. Laser-enhanced electroless deposits showed several sharp X-ray peaks caused by crystalline nickel differing from the broad pattern associated with the amorphous structure. This seemed to be related to the reduction of the phosphorus content in the deposits as a result of laser irradiation.
In terms of corrosion resistance, wear resistance and contact resistance, electrodeposited Pd-Ni alloy was a substitute for gold. This report describes the electroless plating of Pd-Ni-P alloys from ethylenediamine complex solutions containing sodium hypophosphite as a reducing agent, and properties of the deposits. The nickel content of the deposits and thier hardness were found to be proportional to the concentration of nickel ion in the baths. The hardness of 63mol% nickel alloy deposit was 750Hv. The deposits showed maximum hardness after heat treatment at 350°C, reaching over 1000Hv for alloys containing 10mol% nickel or more. An increase in the nickel content of the deposits led to some deterioration in solderability, but no appreciable changes were found in contact resistance, even after humidity testing for six days.
Porous anodic oxide films on Al with a small diameter were formed in (a) 15% sulfuric acid at 20V and the films with a large one were obtained in (b) Kalcolor solution at 80V. Then the specimens were cathodically electrolyzed in the same solution and the films (membranes) were detached from Al metalic substrate by hydrogen gas evoluted at the bottom of the pores. Scanning Electron Micrographic observation revealed no barrir layer for either of the films produced from (a) or (b). Pores in the films formed from (a) were linked together due to irregular dissolution, while for films formed in solution (b), the film structure was almost regular, with much less pore-linkage. The permeation behavior of ions in the prepared membranes was examined with Fe3+ -sulfosalicylate and Ni2+ -sulfate solutions by applying a constant voltage of 30V. To avoid hydration of the membranes in the humid atmosphere, it was neccessary to keep the membranes in a desicator before the experiment. With the membranes prepared, anions were easier to permeated more easily than cations because the alumina membranes in acidic solutions have positive zeta potential, with the result that only anions adsorb on the inner surfaces of the pores and migrate towards the anode during the electrodialysis.
Aluminum plate of 99.87% purity was anodized at a constant voltage of 16.00V d.c. in 1.5mol·dm-3 sulfuric acid at 20°C. The oxide film was detached and either the porous layer or the barrier layer was coated by dipping in acrylic melamine resin. Organic films were obtained by chemical dissolution the oxide films constituent of the composite films. The goniometric transmittance of the composite films obtained by coating the barrier layer was equal to the value for the detached oxide films. The goniometric transmittance of the organic films was similar to the value calculated from Fresnel's equation by assuming the refractive index of the organic films to be 1.55. Meanwhile, the goniometric transmittance of the composite films which were coated on the porous layer was clearly decreased at an incident angle of 10°∼35°. In these composite films, the goniometric transmittance of the organic films was obviously lower than that of the original composite films and they were opaque in appearance. Microscopic observation showed that the surface of the organic films attached to the porous layer had numerous dents. The opaqueness of the composite films seemed to be due to degradation of the organic films by H3O+, HSO4- and SO42- ions in the pores or on the cell walls.
The effects of inorganic inhibitors on pitting corrosion of aluminum and its alloys were studied in NaCl solutions with and without ethylene glycol and a trace of cupric ions. The addition of MgSO4 and NaHCO3 was effective as of either Na2CrO4 or NaNO3 in preventing corrosion. The addition of ethylene glycol resulted in some increase in pit depth but had virtually no effect on the effectiveness of these corrosion inhibitors. An oxide film composed of a basic salt of Al and Mg was deposited on the alloy surface when the specimen was exposed to dilute NaCl solution containing MgSO4 and NaHCO3 at temperatures higher than 40°C, and ethylene-glycol did not affect the formation of this film. When the specimen was covered with this protective film, the corrosion potential moved to the negative and the pitting potential tended toward the positive, so that the resistance to pitting corrosion was markedly improved.