This paper describes an experimental study of a particle removal mechanism in ultrasonic cleaning used in the electronic device manufacturing process. The results are stated briefly as follows;
(1) In ultrasonic cleaning, the scrubbing action of resonant bubbles removes particles.
(2) Neither the cleaning mechanism nor ability depend on ultrasonic frequency from 37kHz to 1MHz.
(3) Ultrasonic cleaning effectively removes perticles larger than 0.2μm in diameter.

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Anti-microbial materials were synthesized with silver thiosulf ato complex R_p[Ag_q(S₂O₃)_r](R=Na, K) on silica gel. Thermal stability of the materials was better with a potassium salt than a sodium salt. It was suggested that the change of cation “R” of the complexes from Sodium to Potassium resulted in thermal stability against oxidation after decomposition of the complexes. Among several cations for the complex, potassium was the most suitable. Potassium salts of the complex K_p[Ag_q(S₂O₃)_r] were synthesized with various ratios of r/q from 1 to 8. With various ratios of r/q, each sodium or potassium salt of the complex was kneaded with resin, and the color difference value ΔE of the surface against natural resin was measured. TG-DTA measurements showed minimum thermal stability at r/q=4 and maximum at 6. Color measurements showed lower ΔE values with K salts than Na salts. The ΔE values of both salts showed peaked at r/q=4 and decreased at 6. Results of thermal stability TG-DTA measurements showed an agreement with the result of color measurements. It was thus suggested that the complex of potassium salt with an S₂O₃/Ag ratio of “6” had superior properties among the complexes for thermal stability against kneading treatment with resin. The chemical composition of the complex was K₁₁[Ag(S₂O₃)₆].

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Corrosion resistance of Al-Mg-Si aluminum alloy with conversion coating treated in magnesium sulfide solution has been investigated electrochemically. Polarization measurements in 0.01M-NaCl solution showed that the coatings had two corrosion prevention effects; Both decreased corrosion potential (E_corr.) and increased breakdown potential (E_break), with temperature and time. Analysis of the coatings revealed that film thickness and Mg composition (Mg/Al) in the film also varied depending on treatment conditions. Thus, corrosion resistance was discussed in terms of the variation of E_corr. and E_break with respect to film characteristics.

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Chipping on exposed automobile panels was investigated in the laboratory using a gravel-o-meter and a model tester. The results show that upon impact with a flying stone, the force of friction plays a significant part in causing chipping damage to the panel. Finite element computation based on the elasitic-plastic deformation model considering frictional force revealed that the paint film suffers more chipping damage than the metallic coating does. This is in agreement with the experimental results of the garvel-o-meter test. Chipping damage is greatly affected by the Young's modulus of the chipping primer. Thus the proposed method is confirmed to be useful for analyzing the chipping mechanism and designing the paint system.

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The image clarity of the electrodeposited coating of an organic coating without hydrophilic resin was inferior because a long wavelength element of 400μm or more remained on the electrodeposited coating after baking. The wettability of the organic coating was improved by adding a hydrophilic resin. It is assumed that the electrodeposited coating of the organic coating with high wettability has excellent image clarity because hydrogen gas separates quickly from the coating, reducing the size of the pores in the electrodeposited coating formed by the hydrogen gas. Using results for the size of the hydrogen gas capable of existing at the interface between the organic coating and electrodeposited coating material calculated with a static model in which the interfacial tension between the solid phase and liquid phase was in balance with the buoyancy of the gas bubbles, it was possible to explain the relative size of the pores in the electrodeposited coating by the contacl angle of the organic coating.

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Amethod of evaluating the continuity of the weld nugget in mash seam can body welding was developed. In this method, the change in electric resistance at the interface between the materials is measured with a rectangular current pulse during spot welding. Weldability is affected by the difference in the initial and final material interface resistance and by the rate of increase in interface resistance. Materials which have a wide welding current range in mash seam welding show lower initial and higher final interface resistance. Increasing the welding electrode force, which widens the welding current range in seam welding, reduces the rate of increase in interface resistance. These phenomena are attributed to the welding current path, which is affected by material interface electric resistance.

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In this paper, the anodizing of aluminum was investigated using water-soluble aromatic amine (benzylamine) to compare with aliphatic amine. Investigations were conducted to determine optimum bath compositions for the anodizing of aluminum in organic alkaline baths (benzylamine-fluoride base) involving ammonium fluoride and organic acid salts (HCOONH₄, CH₃COONH₄, (NH₄)₂C₂O₄, (NH₄)₂C₄H₄O₆, (NH₄)₃C₆H₅O₇). In the case of anodizing in baths containing organic acid salts, uniform films were formed, but non-uniform films were formed in baths without these additives. The thickest film (about 8μm) was formed in a 0.05mol/L benzylamine bath containing 0.1mol/L ammonium fluoride and 0.3mol/L ammonium acetate or in a 0.2mol/L benzylamine bath containing 0.1lmol/L ammonium fluoride and 0.2mol/L ammonium tartrate by anodizing for 30min at 20°C with a current density of 1A/dm². The film formed in the 0.2mol/L benzylamine bath containing 0.1mol/L ammonium fluoride and 0.1mol/L ammonium tartrate was the hardest (Marten's scratch hardness test, load 50gf, about 13) and the film formed in 0.1mol/L benzylamine bath containing 0.1mol/L ammonium fluoride and 0.1mol/L ammonium citrate showed the highest corrosion resistance. SEM observation found that pores of films prepared in back containing ammonium acetate were about 30∼50nm in diameter, while these prepared in baths containing other organic acid salts were about 50nm.

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