Laser irradiation effects on adhesive properties of A5052 aluminum alloy sheet were examined. A hot melt adhesive sheet comprising polyamide resin was used as the adhesive. The shear strength of adhered specimens was measured using tensile testing. The joining strength was inferred as equal to the shear strength. The laser-irradiated surface changed slightly for high laser scanning speeds. Then ruggedness formed on the surface at lower laser scanning speeds. A spire-like surface was formed, especially when the scanning speed was 50-100 mm/s. Laser irradiation under these conditions exhibited adhesiveness sufficient for plastic deformation of the aluminum substrate. Results showed that the joining strength was attributable to the anchor effect.
We strove to produce a microdiamond（MD）- copper composite by electroplating. Unfortunately, copper is naturally non-wetting with MD because of their chemical incompatibility. We achieved modification of the amino group for the MD surface using a photocatalytic treatment, followed by electroplating of the copper. Results demonstrated that the MD - copper composite material assisted by photocatalysis markedly improved their interfacial affinity and thermal conductivity.
Vacuum ultraviolet （VUV） irradiation was applied to photo-activation bonding of polyoxymethylene （POM） plates. The photo-activated POM plates were bonded directly below the melting point. Their VUV-irradiated POM surfaces were analyzed using X-ray photoelectron spectroscopy （XPS） and Fourier transform infrared spectroscopy （FTIR）. Results of these analyses suggest that the VUV irradiation introduced hydroxy groups through oxidation, mainly of ethylene units.
Electroless Pd/Au plating was developed for metal finishing applicable to a fine Cu pattern. Conventionally, Pd activation with a substitution reaction is used for the electroless Pd/Au plating process, but a concern persists that the process might degrade the solder joint reliability. Therefore, we newly investigated Co activation with a reduction reaction. Our findings confirmed the improved solder joint reliability.
Evaluation of external stress-type whisker growth on Sn-plated films after reflow and after preparation under periodic reverse current revealed short whiskers, which were evaluated using ball intender method. Furthermore, XRD analysis results confirmed the presence of multiple crystal planes.
For this study, we investigated anodization to improve the adhesion and corrosion resistance of A5052 aluminum alloy. Sulfuric acid anodization was found to have excellent corrosion resistance but poor adhesion. Phosphoric acid anodization showed excellent adhesion but poor corrosion resistance. Two-step anodization with phosphoric acid anodization and sulfuric acid anodization produced both excellent adhesion and corrosion resistance.
As described herein, this study examined the influence of a plasma irradiation on the deposit geometry of Ni-W on Ni. From FT-IR images, it became evident that hydroxyl improves the hydrophilic property of Ni. From XPS findings, we infer that hydrocarbon removal on Ni and change from the Ni surface to hydrophilic Ni2O3 improved the Ni-W deposit geometry.