The oxidation of several kinds of solder bumps was investigated using sequential electrochemical reduction analysis (SERA) and Transmission Electron Microscopy analysis. Also, the bondability of these solder bumps was evaluated using a newly developed method, which we call the “Bump Fusion Test.” For SAC solder, a very thin amorphous SnO layer was formed on the top surface of the bumps, and a mixture of crystalline SnO and SnO₂ was found after long-term aging. High Ag content of the solder bumps suppresses their surface oxidation. The result of the “Bump Fusion Test” was consistent with that of the SERA analysis and we are able to evaluate the influence of the thickness of the surface oxide layer on the bondability of solder bumps.

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This paper describes an automated method of visually inspecting printed wiring board patterns. With existing inspection methods, a detected pattern is first binarized, and then out-of-rule features or unmatched portions between the detected pattern and the standard pattern are detected as defects. The proposed inspection method detects both deformation and discoloration of the pattern as defects. The conventional inspection method for this purpose subtracts a standard pattern from the pattern to be inspected in gray scale. If the sum of subtraction exceeds the criteria, it is judged that there is a defect in the pattern. This method often gives rise to false alarms, judging deformation within tolerance levels and misalignments as defects. The new inspection method takes account of the direction of the density change of the pattern edge for subtraction. Experimental results revealed the effectiveness of the proposed method to suppress false alarms compared with the conventional method.

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In this study, we propose a method for estimating the anisotropic material properties of glass fiber reinforced plastic (GFRP) from the in-plane elastic modulus. The anisotropic material properties have to be determined and taken into consideration in order to predict the GFRP deformation using the finite element method (FEM). We used a homogenization method to calculate the anisotropic material properties. To do this, the material properties of the glass fiber and resin have to be input. However, the material properties of the resin are sometimes unknown, due to changes in the material properties resulting from variations in the manufacturing conditions. We predicted the anisotropic material properties of the GFRP in this study by inputting the in-plane material properties of the GFRP to the response surface. We applied this method to the GFRP for a printed circuit board, and calculated the anisotropic material properties without any resin material properties.

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This article describes the development of an electro-optic (EO) optical beam deflector using KTa_1-xNb_xO₃ (KTN) crystal. The combination of the substantial second-order EO (Kerr) effect of the KTN crystal and control of the electron injection into the crystal makes the deflection angle appreciable. The operation principle of this fast and significant deflection is described. Wavelength-swept light sources for optical coherence tomography (OCT) have been built equipped with a KTN deflector. An external cavity laser diode (ECLD) configuration that incorporates such a KTN deflector was used. In this ECLD, the output wavelength was swept by the deflection angle of the KTN deflector. A 200-kHz scan rate was obtained with a 20 mW average output power at a scan range of over 100 nm. The measured coherence length was 7 mm. Tomographic images of some biological tissue were successfully obtained using the swept-light-source OCT system.

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Recently, intra-body communication using electric-field technology is attracting attention. However, it has not yet been put into practical use due to the difficulty of engineering these devices. At the same time, the apparatus design of modern simulation technology is essential. However, in the voltage method of intra-body communication technology, only an electromagnetic field simulator is used. If a circuit simulator like SPICE is applicable, intra-body communication device design may become markedly simpler. Therefore, we examined whether SPICE is usable for the voltage method of intra-body communication technology. Our results confirmed the possibility of using SPICE for the analysis of intra-body communication.

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