Ōsaka, Japan
Ōsaka, Japan

Time filter

Source Type

Jalkanen T.,University of Turku | Makila E.,University of Turku | Suzuki Y.-I.,C. Uyemura and Co. | Urata T.,Kyoto University | And 4 more authors.
Advanced Functional Materials | Year: 2012

Preparation of graded-index optical microcavities based on porous silicon is demonstrated, and chemical modifications for obtaining improved stability under alkaline conditions are studied. Four surface modification methods for stabilizing the samples are examined, and the effects on the optical properties are verified. Two different thermal carbonization treatments resulting in hydrophilic and hydrophobic surfaces are employed. In addition, modification with undecylenic acid is performed on as-prepared and thermally hydrocarbonized porous silicon surfaces. Stability and sensing capabilities of the modified samples are examined by subjecting them to different concentrations of methylamine and trimethylamine vapors. Vapor induced changes in the reflectance spectra are used for evaluating sensitivity and stability. Sensitivity towards ethanol vapor is also measured in order to compare the sensitivity to a normal organic solvent. The results show that the two carbonization treatments and the undecylenic acid functionalization of the hydrocarbonized surface result in greatly improved stability. In contrast, derivatization of as-prepared porous silicon with undecylenic acid does not protect the surface sufficiently against oxidation under the highly basic conditions produced by the amine vapors. Surface chemistry is also shown to have a large effect on sensitivity towards the examined vapors. X-ray photoelectron spectroscopy was used to assess changes in elemental composition of sample surface. The results suggest that thermally promoted addition of undecylenic acid on hydrocarbonized porous silicon is an effective method for producing highly stable optical structures with a carboxyl group functionalization. © 2012 WILEY-VCH Verlag erlag GmbH & Co. KGaA, Weinheim.


Kim K.-S.,Hoseo University | Kim S.-S.,Osaka University | Yorikado Y.,Osaka University | Suganuma K.,Osaka University | And 2 more authors.
Journal of Alloys and Compounds | Year: 2013

The establishment of lead-free plating technology and countermeasures for whisker formation are some of the critical issues remaining to be solved for lead-free electronics packaging. This study examined a method for mitigating Sn whisker formation by depositing a thin metal layer, such as Au, Pd and Ni, on pure Sn plating. Au, Pd and Ni layers with thicknesses ranging from 50 nm to 200 nm were deposited on matte Sn plating using a flash-coating process. The Sn whisker growth behavior of pure Sn plating and metal layer/Sn plating samples at room ambient over a period of 10,000 h was observed. The metal layer/Sn plating was considerably more stable against Sn whisker formation in room ambient environment than the pure Sn plating. © 2012 Elsevier B.V. All rights reserved.


Jo J.-L.,Osaka University | Kim K.-S.,Hoseo University | Sugahara T.,Osaka University | Nagao S.,Osaka University | And 3 more authors.
Journal of Materials Science: Materials in Electronics | Year: 2013

Long term surface evolution of matte tin electroplating has been investigated under room temperature to understand the tin whisker mitigation by a trace amount of lead addition. No whisker growth has been observed on all the Sn-xPb samples (1 ≤ x ≤ 10 wt%), while at least 3 wt% of Pb addition is required to alter the columnar grain structure of pure Sn plating to equiaxed grains. The mitigation mechanism by such a trace amount of Pb is not caused by the grain texture control, but is due to the less inter-metallic composite (IMC) growth; the segregated Pb at the columnar grain boundaries disrupts the IMC growth, and releases Sn grain boundary migrations to relax the internal stress. This mechanism of stress relaxation and whisker growth suppression suggests that lead-free Sn plating without whisker growth can be realized by co-plating Sn with a Pb-like metal element that precipitates at the grain boundary to interfere with the IMC growth. © 2013 Springer Science+Business Media New York.


Ohara K.,C. Uyemura and Co. | Tong L.Z.,C. Uyemura and Co. | Sakita K.,Taikisha Ltd | Hayashi Y.,Taikisha Ltd
Transactions of the Institute of Metal Finishing | Year: 2010

It is known that a whole automotive body is so large and complicated that, until now, only a portion possessed of a thin coating film can be taken into consideration in analysing the film thickness of electrodeposited paint coating. In order to examine electrode arrangement, bath structure and the effect of body size, coating voltage, coating time and so on, an analysis of the whole body structure is necessary. In this work, a virtual surface with a simplified shape is introduced, and an analysis of the whole body is realised. The ratio of the active area and superficial area on the virtual surface is defined as a surface coefficient, which is used in the governing equations for the analysis of film thickness of electrodeposited paint coating. A computer experiment involving four models has been performed, and the calculated results verify the effectiveness of the virtual surface's model. Finally, the analysis of a whole automotive body, including the solution of film thickness of side sill possessing of a bad, uneven film layer distribution, is achieved using the virtual surface's model. © 2010 Maney Publishing.


Kaneko Y.,Kyoto University | Hiwatari Y.,Toyota Physical and Chemical Research Institute | Ohara K.,C. Uyemura and Co. | Asa F.,C. Uyemura and Co.
ECS Transactions | Year: 2011

The effects of additives in copper electrodeposition have been studied by using the multi-scale kinetic Monte Carlo simulation. Recently we have extended the solid-by-solid model for crystal growth to a multiple scale model for the simulation of the copper deposition from electrolytic solution. The system consists of the electrode, the solution and the diffusion layer. The solution contains copper ions and the model additives of chloride ions, polyethylene glycol (PEG) and bis(3-sulfopropyl) disulfide (SPS). We have performed the simulations of copper deposition with different combinations of the additives and studied the surface morphology. The suppressing effect of PEG and the accelerating effect of SPS have been confirmed. ©The Electrochemical Society.


Kaneko Y.,Kyoto University | Hiwatari Y.,Toyota Physical and Chemical Research Institute | Ohara K.,C. Uyemura and Co. | Asa F.,C. Uyemura and Co.
ECS Transactions | Year: 2010

A multi-scale kinetic Monte Carlo method has been developed for the molecular simulation of electrodeposition. The basic system is the solid-by-solid model which is a new model for crystal growth with vacancy formation. This model is extended to include the solution and the diffusion layer to take into account the concentration overpotential. The migration of ions in solution is simulated by the coarse-grained random walk. Since the time and length scales in the diffusion layer are largely different from those of the atomic events on the electrode surface, a multi-scale simulation method has been used for the diffusion layer. We have performed the simulation of copper electrodeposition and confirmed that the shape evolution of the surface can be simulated with the formation of the concentration gradient in the diffusion layer. ©The Electrochemical Society.


Tong L.Z.,C. Uyemura and Co. | Ohara K.,C. Uyemura and Co. | Asa F.,C. Uyemura and Co. | Sugiura Y.,C. Uyemura and Co.
Transactions of the Institute of Metal Finishing | Year: 2010

This work presents an extensive computational fluid dynamic (CFD) study of eductor agitation in an electroplating tank. The mathematical model of the hydrodynamic properties is presented and verified in a velocity measurement cell, in which the calculation results are in good agreement with the measured values. The model is used to examine the behaviour of fluid flow in an electroplating tank, especially in the vicinity of printed circuit board and shields. The influence of the shields on solution recirculation is analysed and discussed. The results indicate that solution recirculation could be improved when the eductors are arranged inclined to the printed circuit board. © 2010 Maney Publishing.


Kaneko Y.,Kyoto University | Hiwatari Y.,Toyota Physical and Chemical Research Institute | Ohara K.,C. Uyemura and Co. | Asa F.,C. Uyemura and Co.
Electrochimica Acta | Year: 2013

In this paper we present the Kinetic Monte Carlo simulation system for the simulation of three-dimensional shape evolution with void formation as a model for electrodeposition. The basic system is the Solid-by-Solid model which is an extension of the conventional Solid-on-Solid model for crystal growth to include void formation. The advantage of the Solid-by-Solid model is that complex three-dimensional shape evolution accompanying void formation (from point defects to macro voids) can be simulated without the difficulty of treating moving boundaries. This model has been extended to include the solution part in which the migration of ions is simulated by the coarse-grained random walk. A multi-scale method is employed to generate the concentration gradient in the diffusion layer. The extended model is applied to the simulation of via and trench fillings by copper electrodeposition. Three kinds of additives are included: suppressors, accelerators and chloride ions. The mechanism of void formation, effects of additives and their influence on the bottom-up filling are discussed within the framework of this model. © 2013 Elsevier Ltd.


Jo J.-L.,Osaka University | Nagao S.,Osaka University | Hamasaki K.,Osaka University | Tsujimoto M.,C. Uyemura and Co. | And 2 more authors.
Journal of Electronic Materials | Year: 2014

In this study, the morphological development of electroplated matte Sn and Sn-xBi (x = 0.5 wt.%, 1.0 wt.%, 2.0 wt.%) film surfaces was investigated under diverse testing conditions: 1-year room-temperature storage, high temperature and humidity (HTH), mechanical loading by indentation, and thermal cycling. These small Bi additions prevented Sn whisker formation; no whisker growth was observed on any Sn-xBi surface during either the room-temperature storage or HTH testing. In the indentation loading and thermal cycling tests, short (<5 μm) surface extrusions were occasionally observed, but only on x = 0.5 wt.% and 1.0 wt.% plated samples. In all test cases, Sn-2Bi plated samples exhibited excellent whisker mitigation, while pure Sn samples always generated many whiskers on the surface. We confirmed that the addition of Bi into Sn refined the grain size of the as-plated films and altered the columnar structure to form equiaxed grains. The storage conditions allowed the formation of intermetallic compounds between the plated layer and the substrate regardless of the Bi addition. However, the growth patterns became more uniform with increasing amounts of Bi. These microstructural improvements with Bi addition effectively released the internal stress from Sn plating, thus mitigating whisker formation on the surface under various environments. © 2013 TMS.


Patent
C. Uyemura And Co. | Date: 2012-11-01

A manufacturing method of a buildup circuit board includes forming a wiring layer on an organic polymer insulating layer by copper electroplating and building up other organic polymer insulating layer on the wiring layer, wherein in a final step of the copper electroplating, a surface of the wiring layer is roughened by copper electroplating and the organic polymer insulating layer is formed directly on the roughened surface of the wiring layer. According to the invention, a specific etching step that is essential for enhancing adhesion between the organic polymer insulating layer and the wiring layer can be omitted and no expensive etching apparatus is necessary, thus being good in economy. In addition, if various types of copper sulfate plating baths containing different types of additives used for via fill plating are used as they are, irregularities on the surface can be made in various forms and roughnesses. Thus, it is necessary to select a specific type of etching solution depending on film characteristics ascribed to types of additives. Moreover, it is easy to form surface irregularities in conformity with the type of material and physical properties of the organic polymer insulating layer being built up.

Loading C. Uyemura and Co. collaborators
Loading C. Uyemura and Co. collaborators