Papers by Author: Masumi Saka

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Authors: Bing Feng Ju, Yang Ju, Masumi Saka
Abstract: An ultra-precision instrument with concomitant micromanipulation techniques is designed and set up to measure the damage strength of a single biomimetic microcapsule. It can provide the capability of simultaneously measuring the applied force and resultant displacement of a single microcapsule, with maximum force range of 5mN, resolution of 0.1µN and ultimate traveling distance up to 12mm, resolution of 1nm, respectively. By armed high magnification side-view system, it can offer extra and withal valuable information for the supervened analyzing. The bursting force of urea-formaldehyde biomimetic microcapsules of diameter 65µm in glucose solution was measured by this technique. The microcapsule was burst when the deformation reached a value of 56.2% of its diameter and the corresponding resonant force is about 1700µN. The technique provides an effective means to characterize elastic properties of micro biomimetic capsules and compare mechanical strength of microcapsules made of different ingredients.
Authors: Shien Ri, Takashi Muramatsu, Masumi Saka
Abstract: Recently, a technique for fast and accurate phase analysis called sampling moiré method has been developed for measurement of small-displacement distribution. In this study, a distribution of phase error caused by linear interpolation in case with mismatch between the sampling pitch and the grating pitch is theoretically analyzed. Moreover, a technique for effective phase compensation is proposed to reduce the periodic phase error. The performance of our compensation method is validated by a computer simulation. Phase analysis can be performed more accurately even in the case that the sampling pitch does not match to the grating pitch strictly.
Authors: Takashi Hasegawa, Toru Kohara, Masumi Saka
Abstract: General thermometers pose difficulty in measuring the actual surface temperature of a micro-area, especially in electronic devices. In the present study, an approach to direct measurement of surface temperature is described, which utilizes the potential of melting point of different chemical reagents. The present technique exhibits a temperature resolution of about 5○C and the measurable maximum temperature of about 200○C. A short comment on the application of the technique to determine the actual surface temperature of small areas in some engineering applications is also stated.
Authors: Fumio Takeo, Kanako Nakajima, Takeru Baba, Yuki Aonahata, Masumi Saka
Authors: S. Reaz Ahmed, Masumi Saka, Fumio Takeo
Abstract: A direct-current potential-drop NDE technique has been developed for the evaluation of a 3-D back-wall crack in thick-walled structures. The measuring system contains two pairs of probes – one for current supply and the other for the measurement of potential-drop, where the currentsupply and measuring probes are in close proximity to each other. The optimum arrangement of the four-point-probes system is determined from the finite-element simulation of the three-dimensional electric crack problem. The predicted potential-drop across the crack has been verified experimentally using the newly developed measuring sensor. Measured results of semi-elliptical cracks in stainless steel plates establish the practicality as well as reliability of the present potentialdrop method of testing for the evaluation of 3-D back-wall cracks in thick-walled structures.
Authors: Takashi Hasegawa, Masumi Saka
Abstract: Solder is the most frequently used alloy, which serves as the bonding metal for electronics components. Recently, the interconnected bump is distinctly downsizing its bulk along with the integration of high-density packaging. The evaluation of electromigration damage for solder bumps is indispensable. Hence, it is fairly urgent to understand the mechanism of the electromigration damage to be capable of securing reliability of the solder bump and ultimately predicting its failure lifetime. Electromigration pattern in multi-phase material is determined by the combination of current density, temperature and current-applying time. In this paper, diagram of electromigration pattern (DEP) in solders is presented, where both of eutectic Pb-Sn and Pb-free solders are treated. DEP gives the basis for discussing and predicting the electromigration damage in solders.
Authors: D.O. Macodiyo, H. Soyama, Masumi Saka
Abstract: Peening can be used to produce a layer of compressive residual stress at the surface of components which are subject to fatigue or stress corrosion, thereby retarding crack initiation and/or impeding the development of new cracks and hence improving their fatigue life. We have developed a new peening method, Cavitation Shotless Peening (CSP), which makes use of cavitation impacts induced by the collapse of the cavitation bubbles to produce compressive residual stress and work hardening on the material surface. CSP is a surface enhancement technique which differs with shot peening in that shots are not used. CSP uses a submerged high-speed water jet with cavitation, herein referred to as a cavitating jet, whose intensity and occurring region can be controlled by parameters such as upstream pressure and nozzle size. Cavitation number , which is defined by the ratio of upstream pressure to downstream pressure, is the main parameter of the cavitating jet. In this paper, the pit distribution on the specimen was observed with cavitating numbers  = 0.0057 and  = 0.0142. The improvement of fatigue strength and introduction of residual stress were investigated for both conditions using carburized alloy steel (JIS SCM415). It was evident from a comparison between non-peened and cavitation shotless peened specimens that the cavitation number has influence on the fatigue strength of metallic materials. Comparison of shot peened and CSP specimens has also been discussed.
Authors: H. Kumano, H. Soyama, Masumi Saka
Abstract: Damage for gettering can be introduced by a high speed submerged water jet with cavitation, i.e., a cavitating jet, into a silicon wafer. Gettering is an important technique for removing unwanted impurities from the surface of the silicon wafer that is active device region. Metal contaminations diffuse in bulk of the wafer and adhere to the defects through the thermal treatments in semiconductor processes. If the damage was intentionally introduced into the silicon wafer, these contaminations can be gathered within the intended region. Consequently, the surface of the wafer can be kept free from impurities. The method presented here utilizes cavitation impacts to introduce the damage for gettering. By using cavitation impacts, the damage can be introduced without the use of particles which form sources of contamination during farther wafer handling, as in shot blasting that is a popular technique. The cavitation impacts caused by a cavitating jet were used since the intensity of cavitation impacts can easily be controlled by controlling hydraulic parameters. The gettering effect of the damage introduced by the cavitating jet was already confirmed, but the detail information of the introduced damage has not been obtained. After applying thermal treatment to the wafer treated by the cavitating jet, there are Oxidation-induced stacking faults (OSF) which would be gettering sites. However, the source of OSF is not yet confirmed. In this paper, the damage on the silicon wafer surface introduced by the cavitating jet for gettering is observed to evaluate the source of OSF.
Authors: Yasuhiro Kimura, Masumi Saka
Abstract: Electromigration (EM) is the phenomenon of atomic diffusion in a metallic film with a high-density electron flow. Our group used EM to fabricate Al micro-materials. The EM technique can be used to fabricate micro-materials with a high aspect ratio, pure metal components, an arbitrary form, and a single-crystal structure. Recently, two micro-materials have been simultaneously fabricated using an array pattern consisting of parallel or series connections. However, multiple micro-materials have not been fabricated simultaneously thus far. In this study, a new comb sample pattern was used with a conductive passivation film to produce multiple Al micro-materials.
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