Photochemical deposition of copper thin films was achieved using carboxylic acid as an electron donor for direct fabrication of minute copper circuit patterns on glass substrates. The photochemical reduction of copper ions could occur over the whole surfaces on which UV irradiation area. However, only the copper deposits remained on the surface of hydrophobic n-octadecyl trimethoxysilane patterns after washing with water. The selective lift-off of the copper films on hydrophilic glass surfaces could be achieved by washing with polar solvents such as water. The thickness of the copper films was easily controlled by varying the UV irradiation time. It has been determined that the mixed potential theory can be applied to this reaction based on the result of the local polarization curve measurement.

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We have fabricated barium titanate thin films using a coating process of nano-sized BaTiO₃ particles dispersed in a suspension prepared using a high-concentration sol–gel method. In this study, in order to fabricate a thin film capacitor embedded on a printed wiring board, we fabricated nano-sized barium titanate particles and deposited a thin film onto copper foil using a roll-to-roll process. The fabricated film had no cracks and the surface was smooth. Also, the capacitance density was 39 nF/cm² and dielectric loss was 7.2%. Furthermore, by means of an epoxy resin coat on the surface of the nano-sized barium titanate particles deposited as a thin film, the electrical characteristics were improved so that the capacitance density was 36 nF/cm² and the dielectric loss was 2.3%.

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A high-power light-emitting diode (LED) using multi-chip integration of small near-ultraviolet (n-UV) LED chips has been fabricated based on the direct flip-chip bonding technique. The luminous flux and the efficacy were evaluated using an integrating sphere under the control of package temperature. The results showed that the external quantum efficiency (EQE), the wall plug efficiency (WPE), and the luminous efficacy decreased with increasing package temperature, but the absorption of light into the adjoined LED chip was not observed. It is observed that the LED chip density was important for increasing luminous efficacy, even if the number of LED chips is the same.

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Foreign objects in a solder joint could deteriorate the joint strength when mounting BGA (Ball Grid Array) packages or CSP (Chip Scale Package) on printed circuit boards. However, foreign objects within solder bumps are not detected by optical inspection which has been used widely. Recently, X-ray computed tomography (CT) for the inspection of printed circuit boards has been developed. X-ray CT visualizes the foreign objects inside a solder joint. If they are automatically detected, higher soldering quality is expected. In this paper, we propose an automated detection method of foreign objects in solder joints using CT slice images. In the method, some characteristic values are identified which show the solder joint deformation. In the experiments, actual mounting substrates involving solder bumps contaminated by foreign objects were checked using the proposed method. The detection accuracy rate reached 98.9%, which clearly indicates that the proposed method is useful in practice.

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We evaluated the semiconductor mounting substrate and investigated the whisker's generations and factors by experimenting different environmental conditions. On the lead consisted of Cu base/Sn plating, the result of the condition 110°C/85% & 120°C/85% which were produced by Air-HAST (HAST with air) generates Sn whiskers faster than other high temperature and humidity tests. We concluded that the factors in the whisker generation are high temperatures, high moisture and oxygen.

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